Modern Civil Engineering

Carbon Fibre Reinforced Polymer: Retrofitting method of RCC elements

2022-08-06T12:53:00.002+05:30

Introduction

One of the biggest issues facing the construction industry for many years has been the damage to reinforced concrete (RC) structures. The majority of the existing buildings are noncompliant with seismic regulations. These structures frequently display flaws like insufficient detailing, broken load paths, and inadequate capacity design considerations. That is further supported by the devastating earthquakes that continue to cause human injuries and deaths in addition to the structural collapse of buildings. Given that disastrous earthquakes can happen anywhere in the world at any time, it is becoming more and more important to help strengthen the existing structures. Although many rehabilitation programs take a lot of time and cause a lot of disturbance because of how difficult it is to apply them, they may not be cost-effective.

RC beams are repaired and strengthened using a variety of techniques. The most popular of these techniques is to steel jacket damaged or weak RC beams in order to repair and reinforce them. The drawbacks of this procedure, which is challenging, time-consuming, and laborious, include a large increase in the weight of the building, the need for additional foundation system arrangements, and the inability to use the structure while it is being strengthened. However, the above-mentioned drawbacks can be minimized by using Fibre Reinforced Polymers (FRPs) as a strengthening material. It is a composite material constructed from a polymer matrix and fibre reinforcement. The most popular fibres are carbon (C), glass (G), or aramid (A), and they are joined by an epoxy, vinyl ester, or polyester matrix. They were initially employed as an external retrofit in buildings in Europe and Japan, but there has been significant advancement in the last 15 years or so.

Carbon Fibre Reinforced Polymer

Carbon fibres are fibres with a diameter of around 5 to 10 micrometres (0.00020–0.00039 in) and are composed of atoms of carbon in the majority of their structure.

The atoms of carbon are linked together in form of crystals that are roughly parallel to the fibre's long axis to create carbon fibre, which has a high strength-to-volume ratio due to the crystal alignment (it is very strong for its size). To create a tow, which may be used on its own or woven into fabric, thousands of carbon fibres are packed together.

To create a composite, carbon fibres are typically mixed with other materials. It can be baked after being infiltrated with a plastic resin to create carbon-fibre-reinforced polymer, also called carbon fibre. Carbon fibre is very rigid, and has a very high strength-to-weight ratio, but is also relatively fragile.

Advantages:

The carbon-wrapped column reinforcing technology is the one that causes the least amount of disturbance to the structural components. Utilizing carbon fibre reinforced concrete or polymers in an efficient manner can considerably extend the life of the structure while also reducing the amount of maintenance that is required. Since the columns that are covered in carbon fibre are resistant to corrosion, they are utilised for corrosion control as well as the restoration of structures made of reinforced concrete. In addition, carbon fibre reinforced concrete and carbon wrapped columns are usually utilized in the construction industry to enhance concrete structures. One of these materials is carbon fibre, which, in order to create a composite, is typically combined with a number of other types of materials. Carbon fibres are one of the most widely used materials in the field of civil engineering due to the properties they possess, which include high levels of stiffness and tensile strength, low levels of weight and chemical resistance, and high levels of temperature tolerance, and low levels of thermal expansion. Its advantages include;

Corrosion resistance
Short construction period
No maintenance required
Increased flexural capacity of column, beam and slabs
Hardening of structural member without significantly increasing its size
Adds strength to concrete
Increased load carrying capacity
Minimal change to structure's shape and appearance
Faster installation
Portection from enviromental degradation

Disadvantages:

Some disadvantages of FRP include its difficulty to adhere to a wet surface, the resin's poor performance at temperatures over the glass-transition temperature, its poor fire resistance, and its lack of vapour permeability.

To increase the shear, flexural, and axial capacity of various reinforced concrete elements, such as columns, beams, slabs, walls etc., it can be applied. Epoxy resins must be utilized in the application to connect FRP to the exterior surfaces of structural components because it is typically used as an externally reinforcing material in the form of plates, sheets, or anchors.

Introduction to Intze type Water Tank and its different components

2022-08-03T11:09:00.001+05:30

Introduction

A large number of liquids retaining tanks are used for storing the water, oil or chemical fluids. These can have circular or rectangular shape in plan and can be built either above or below the ground. The overhead service reservoirs are a common sight. The tanks used for water storage are generally placed at a certain height in order to get the sufficient heads for water supply and firefighting. For this purpose, the tanks are either installed at top of building or at top of supporting structure, which could be in form of shaft or frame type.

Type of Tanks

On basis of position from ground level

Underground Tank
Tanks resting on ground
Elevated/ Overheads tanks

On basis of shape

Circular shaped tanks
Rectangular shaped tanks
Spherical shaped tanks
Intze type tanks

Intze type Tank

The Intze type water tank got its name due to special arrangement of conical dome and bottom dome. In this particular arrangement, the inward force from conical dome and outward force from bottom dome balances out each other to a greater extent at section where conical dome and bottom dome meets which leads to lesser section sizes and reinforcement requirement in intze case while comparing to other shapes. The various components of an overhead water tank are shown and described as below:

i) Water tank portion with

a) Roof

b) Walls

c) Ring beams

c) Floor or bottom slab

d) Floor beams including circular beams

ii) Staging portion, includes

a) Columns

b) Bracing

c) Foundation

a) Top Dome: The top dome serves as covering to top of tank. It also provides the surface to person to clean the tank. Lightening conductor and aviation light are placed on the dome. If the sloshing wave height is greater than the free board, then the top dome is designed for the effective upward pressure. Otherwise, minimum reinforcement is provided in top dome. The thickness usually lies between 100 mm to 150 mm and the rise is about 1/5th of the span.

b) Upper Ring beam: The ring beam is present at junction of top of cylindrical wall and dome edges. The horizontal component of the thrust is transferred to the beam from dome. The ring beam is designed to resist the hoop tension.

c) Cylindrical walls: The wall lies in between the upper and lower ring beam. The wall transferred the vertical load from dome to lower ring beam. The wall is designed for hoop tension induced due to horizontal water pressure.

d) Bottom Ring beam: The bottom ring beam is present at the junction of the cylindrical walls and the conical wall. The bottom ring beam resist the horizontal component of the reaction of the conical wall acting on the cylindrical wall. The ring beam will be designed for same.

e) Conical Wall: The conical wall is designed for hoop tension due to water pressure. The wall will also be designed as a slab spanning between the bottom ring beam at top and the circular ring beam (resting on top of columns) at bottom.

f) Bottom Dome: The bottom dome is supported on the circular ring beam. The dome is designed as slab for vertical load of water.

g) Circular Beam: The circular beam is designed to support the entire tank with its content inside. The beam will be supported on columns and should be designed for resulting bending moment and torsion.

h) Staging: The staging portion includes columns and bracing beam. Columns are designed to transfer the total load including their self-weight to the foundation. Bracing beams are provided at regular intervals to brace columns and have to be designed for wind pressure or seismic loads whichever governing.

In-situ density of natural or compacted soils by using Sand Replacement Method

2020-09-11T18:36:00.006+05:30

Sand Replacement method is used to find in-situ density of natural or compacted soils. Sand Replacement test for determination of density of soil measure the in-situ volume by sand pouring cylinder. In short, we measure weight of excavated soil from hole and volume of hole. Then density can be easily calculated by dividing weight by volume.

The in situ density of natural soil is needed for the determination of bearing capacity of soils, for the purpose of stability analysis of slopes, for the determination of pressures on underlying strata for the calculation of settlement and the design of underground structures.

It is very quality control test, where compaction is required, in the cases like embankment and pavement construction.

APPARATUS REQUIRED

Sand pouring cylinder of 3 litre/16.5 litre capacity, mounted above a pouring come and separated by a shutter cover plate.
Tools for excavating holes; suitable tools such as scraper tool to make a level surface.
Cylindrical calibrating container with an internal diameter of 100 mm/200 mm and an internal depth of 150 mm/250 mm fitted with a flange 50 mm/75 mm wide and about 5 mm surrounding the open end.
Balance to weigh unto an accuracy of 1g.
Metal containers to collect excavated soil.
Metal tray with 300 mm/450 mm square and 40 mm/50 mm deep with a 100 mm/200 mm diameter hole in the centre.
Glass plate about 450 mm/600 mm square and 10mm thick.
Clean, uniformly graded natural sand passing through 1.00 mm I.S.sieve and retained on the 600 micron I.S.sieve. It shall be free from organic matter and shall have been oven dried and exposed to atmospheric humidity.
Suitable non-corrodible airtight containers.
Thermostatically controlled oven with interior on non-corroding material to maintain the temperature between 1050C to 1100C.
A dessicator with any desiccating agent other than sulphuric acid.

THEORY

By conducting this test it is possible to determine the field density of the soil. The moisture content is likely to vary from time and hence the field density also. So it is required to report the test result in terms of dry density. The relationship that can be established between the dry density with known moisture content is as follows:

PROCEDURE

Calibration of the Cylinder

1. Fill the sand pouring cylinder with clean sand so that the level of the sand in the

cylinder is within about 10 mm from the top. Find out the initial weight of the cylinder plus sand (W1) and this weight should be maintained constant throughout the test for which the calibration is used.

2. Allow the sand of volume equal to that of the calibrating container to run out of the cylinder by opening the shutter, close the shutter and place the cylinder on the glass

sand takes place in the cylinder close the shutter and remove the cylinder carefully. Weigh the sand collected on the glass plate. Its weight(W2) gives the weight of sand filling the cone portion of the sand pouring cylinder.

Repeat this step at least three times and take the mean weight (W2) Put the sand back into the sand pouring cylinder to have the same initial constant weight (W1)

Fig: Sand Replacement Test apparatus

Determination of Bulk Density of Soil

3. Determine the volume (V) of the container be filling it with water to the brim. Check this volume by calculating from the measured internal dimensions of the container.

4. Place the sand poring cylinder centrally on yhe of the calibrating container making sure that constant weight (W1) is maintained. Open the shutter and permit the sand to

run into the container. When no further movement of sand is seen close the shutter, remove the pouring cylinder and find its weight (W3).

Determination of Dry Density of Soil In Place

5. Approximately 60 sqcm of area of soil to be tested should be trimmed down to a level surface,approximately of the size of the container. Keep the metal tray on the level surface and excavate a circular hole of volume equal to that of the calibrating

container. Collect all the excavated soil in the tray and find out the weight of the excavated soil (Ww). Remove the tray, and place the sand pouring cylinder filled to constant weight so that the base of the cylinder covers the hole concentrically. Open

the shutter and permit the sand to run into the hole. Close the shutter when no further movement of the sand is seen. Remove the cylinder and determine its weight (W3).

6. Keep a representative sample of the excavated sample of the soil for water content determination.

Fig: Determination of Density of soil

Fig:Determination of density of soil

INITIAL AND FINAL SETTING TIME OF CEMENT

2020-08-09T14:09:00.001+05:30

The initial time of cement is time by which cement turns into paste by mixing with water and begins to lose its plasticity. The final time of cement is time by which cement turns into paste by mixing with water and lose its plasticity completely and have a certain structural strength.

The mixing, transporting and placing of mortar or concrete require a certain minimum time that should be within initial setting time. During this activity time cement paste, mortar, or concrete should be in plastic condition which make working with cement easy. After placing in the final position, compacting and finishing, Cement paste, mortar or concrete should lose its plasticity as early as possible such that there are least chances of damaging from external destructive agencies. This time should not be more than 10 hours which is referred to as final setting time. Initial setting time of cement should not be less than 30 minutes.

AIM: To determine the initial and final setting times of given sample of cement.

APPARATUS: Vicat apparatus with attachments, balance, weights, gauging trowel.

Vicat Apparatus

THEORY: The initial setting time of cements is time interval during which the cement paste, mortar or concrete remain in plastic condition. The Initial setting time can be defined as the time taken by cement paste to start losing its plasticity from the moment of adding water to cement. The final setting time of cement paste can be defined as the time taken by cement paste to lose its plasticity and attain the firmness from the moment when water is added to cement.

PROCEDURE:

Test Block Preparation:

Mix 300 grams of cement with 0.85 times the water required to give a paste of standard consistency to prepare a cement paste.
The water used in preparing the cement paste should either potable or distilled.
The cement paste shall be gauged under the conditions prescribed in determination of consistency of standard cement paste.
Note down the time by starting a stop-watch at the instant when water is added to the cement.
Fill the mould with the cement paste gauged as above while the mould resting on a nonporous plate.
Fill the mould completely and smooth off the surface of the paste making it level with the top of the mould.

DETERMINATION OF INTIAL SETTING TIME:

Place the test blocks along with mould resting on the non-porous plate, under the rod bearing initial setting needle of vicat apparatus.
Then gently lower the needle in contact with the surface of the test block and release the needle quickly, allowing the needle to penetrate into the test block.
The needle will completely pierce the test block in beginning of the test.
Repeat this procedure until the needle fails to pierce the block to a point 33 to 35 mm from top of mould (or 5 to 7 mm measured from the bottom of the mould) shall be the initial setting time.

DETERMINATION OF FINAL SETTING TIME:

Insert the needle with an annular attachment in place of the needle of the Vicat apparatus.
When on applying the needle gently to the surface of the test block, the needle makes an impression there on, while the attachment fails to do so. Then the cement shall be considered as set finally.
The final setting time of cement paste is time gap between the time when water is added to the cement and the time at which the needle makes an impression on the surface of test block while the attachment fails.

PRECAUTIONS:

The appliances should be clean before gauging. All the apparatus shall be free from vibration.
The temperature of water and that of the test room, at the time of gauging shall be 27ᵒC ± 2ᵒC.
Care shall be taken to keep the needle straight.

RESULT: Initial setting time for the given sample of cement =

Final setting time for the given sample of cement =

Modified California Bearing Ratio Method (CBR) - IRC 37 code

2020-07-28T21:24:00.001+05:30

Modified California Bearing Ratio (CBR) method is further advancement of California Bearing Ratio test. Both CBR tests are used for flexible pavement design. CBR method based upon strength of sub grade soil and subsequent pavement material. In modified CBR method, The concept of cumulative standard axle is adopted instead of total number of all commercial vehicle as in simple CBR test.

To know the about the testing procedure of California Bearing Ratio Test, Click Here

In Modified CBR method, Design traffic is defined in term of cumulative standard axle loads of 8170 Kgs (or 8.2 tons) during the design life of the roads, If the design traffic is ore than 1500 vehicles per day.

The following expressions is used to calculate the number of cumulative standard axle N_S:

Vehicle Damage Factor (VDF): It is a multiplier to convert the given number of commercial vehicles which have different axle configurations and different axle weights into an equivalent numbers of standard axle load repetitions

Lane Distribution Factor: It is required for estimating the design traffic to be considered for structural design of pavement. Design traffic means equivalent standard axle load application.

While Designing the Flexible pavement by Modified CBR test, You need only two parameter: CBR test value and Traffic in MSA. After that you need find Indian Road Congress IRC- 37 code: Design of Flexible Pavement.

After finding the Catalogue for calculated CBR value (for reference see the below picture), Refer the Required value of Traffic, and then read the indicated layers and their respective thickness. .

Manufacturing of Portland Cement (Wet and Dry Process)

2020-07-23T13:34:00.000+05:30

The manufacturing of Portland Cement (Wet and Dry Process) comprises of complex process of mixing, heating in a cement kiln and grinding of raw materials i.e. Limestone and Clay which leads to Bouge Compounds formation. The Bouge compounds are actual responsible for properties of cements.

Cement is greenish grey colored fine powder. Cement become hard and strong when mixed with water. This property of cement make the cement a good building materials.

The Cement is manufactured by mixing the calcareous component and argillaceous component by ratio of 3:1.
The calcareous component can be limestone, chalk, marine shells, marl whereas the few examples of argillaceous components are shale, clay, blast furnace slag and slate.
Lime is main source of extraction of calcareous component whereas argillaceous component consists of silica, alumina, iron oxide and other impurities.
The cement is manufactured by two processes: Wet Process and Dry Process.

1.Wet Process:

It is the old process of manufacturing which is no longer in use.
It requires high degree of fuel consumption and power consumption which leads to increase the manufacturing cost.
No preheater is required in this case.

2.Dry Process:

It is a new method of manufacturing method in which fuel and power consumption has been reduced to larger extent.
Preheating is done by Exhaust gas which help in reducing the manufacturing cost.
Dry process is used majorly for manufacturing of cement.

Different zone in the process

1. Nodule Zone:

The calcination of limestone occur in this zone. Limestone get disintegrated into two component- Lime and carbon dioxide.
When CO₂ is evaporated from the mix, the raw mix is converted into nodules.

2. Burning Zone:

In this zone, integration of calcareous and argillaceous compounds i.e. lime, silica, alumina, iron oxide etc. get united with each other at a very high temperature and this process is called fusion.
In this zone, the following reaction take place

2CaO + SiO₂ Ca₂SiO₄= C₂S (Dicalcium Silicate)

3CaO + SiO₂ Ca₃SiO₅ = C₃S (Tricalcium Silicate)

3CaO + Al₂O₃ Ca₃Al₂O₆ = C₃A (Tricalcium Aluminate)

4CaO + Al₂O₃ + Fe₂O₃ Ca₄Al₂Fe₂O₁₀ = C₄AF (Tetra- Calcium Alumino- Ferrite)

The above four compound obtained from rotary kiln are known as Bouge Compound.

A Complete Guide: Design, Working & Benefits of Slow Sand Filter

2020-05-01T18:41:00.000+05:30

Slow Sand Filter (Gravity type) are most effective (98-99% bacteria removal) and widely used for purification of water in small villages & communities where water demand is comparatively low. Slow Sand Filter comes under the heading of Gravity Filtration system which are designed for maximum daily demand of that area.

Gravity Filtration System

Gravity system is one in which water flows under gravity or water head is required for water flow. Gravity System is generally classified into two system:

Slow Sand Filtration
Rapid Sand Filtration

Slow Sand Filters

Slow Sand Filter Diagram

Slow Sand Filter utilize the effluent either from plain sedimentation or directly from sources. Sand Filters medium comprises of Sand, geo textile, gravels. A gravel layer is provided only to provide support to fine sand layer.

Various design specification of Slow Sand filter are as follows:

Generally rectangular in shape.
Depth of tank is in range of 2.5 to 3.5 m.
Effective size (diameter) of Sand particle are of 0.2 to 0.3 mm.
Coefficient of uniformity varies in range of 3 to 5.
Top layer of sand (15 to 30 cm) out of total depth is of fine variety and rest is of uniform size.
Depth of water equals to Depth of sand filter itself.
Rate of filtration is in range of 2400- 4800 L/sq.m/day or 100-200 L/sq.m/hour.

Working of Slow Sand Filter

The basic force on which entire filter works is Biological action. When the water is passed through the filter. After some time a gelatinous layer known as Schmutzdecke, is formed over the sand particle. It consist of a variety of bacteria, fungi and other tiny micro organism.It is the layer which provide effective cleaning of water. The Schmutzdecke layer capture the foreign matter which are present in water and then the micro organism decompose it.

Slow sand filter slowly lose their performance as the biofilms thickens which further lead to loss of water head. To increase the performance of slow sand filter again, Cleaning of sand filter become necessary.

Cleaning of Slow Sand Filter

Cleaning of Sand filter should be done when head loss become 0.7 to 0.8 times of depth of filter medium.
Freshly cleaned filter had head loss of 10-15 cm that goes on increasing with time
For cleaning sand filter, top 15 to 30 cm of sand layer is removed with help of rack and washed with water.
Once the cleaning is completed, Slow Sand Filter is again loaded with water for filtration but filtered water is not used for next 24 to 36 hours.
Frequency of cleaning is 1-3 months.

Total number of Slow sand filters required for filtration process according to requirement of air are given below:

Requirement of Slow Sand Filter

Advantage

The bacteriological efficiency is in range of 98-99 %. Effluents of filter has comparatively less nutrient. Hence if send in distribution system, The chances of growth of micro organism and algae is very less.

Sand filter work on very less mechanical power and chemicals. Hence the minimal staff is required with basic training only.

Disadvantage

Slow Sand Filters only work if turbidity of incoming water is less than 50 NTU because the filter get choke very frequently on working of water having turbidity > 50 NTU, require more cleaning. Hence increase operational cost of filter.

SCREENING AND AERATION (METHOD OF WATER TREATMENT)

2020-03-20T17:58:00.000+05:30

1.Screening

It is the process of removal the heavier suspended solids from the water like plants, stones, animals, tree or other waste etc.
It also help to protect the heavy and costly machinery like pumps or pipes from any potential damage or choking from heavy suspended solids.

Screening can be broadly classified into two types of screens:

Coarse screens
Fine Screens

a.Coarse screens (Bar screen/ Trash racks)

The screen are in the form of bars of diameter 10-20 mm and spacing of 20-100 mm between them.
These screens are always placed at inclination of 3-6 vertical to 1 horizontal as it helps in effective cleaning of screening by racking mechanism.
When water passes through screens, loos of head of water take place, the magnitude of which is given by:

b.Fine Screens

Fine screens in the form of wire mesh of size 10mm.
Under normal treatment, Fine screens are generally avoided as it get frequently choked.
It also requires cleaning at short intervals, thus increases operational cost.
The GOI manual suggest the use of coarse screen instead of fine screens and remove the finer particles in other treatment stages.

2. Aeration

It is the process in which water is brought in contact of oxygen.
Remove dissolved gases like H2S and CO2.
Carry out the oxidation of undesirable substances like organic matter and oils
Removes volatile liquid like phenols, humic acids from water.
Remove the dissolved minerals like Fe, Mg etc.
Remove colour, odour and taste.
Increase acidity and turbidity of water.
Generally adopted for treating of water which is devoided of oxygen such as ground water or water at bottom of lake.

Methods of Aeration

a.Spray Nozzle Method

Most efficient method
Pressurized water is used to increase surface area of water.
Used when quantity of water is less.

b.Cascade Aerator

Efficiency is less (about 40%).
Generally used in treatment plants.

c.Spray Tower Method

Best method to remove iron, manganese and CO2.
require more area for functioning.

d.Diffused air Method

It has highest operational cost.
Used when area is limited.

DIFFERENT TYPE OF WATER DEMAND AND PER CAPITA DEMAND

2020-03-19T09:59:00.000+05:30

The water demand of any city can be classified into following categories:

1.Domestic Water Demand

Water required for domestic purposes such as washing, drinking, cooking, gardening, etc.
GOI manual consider Domestic water usage limit between 135 LPCD to 225 (Litre Per Capita per Day).
For a town with full flushing system, the minimum domestic water requirement should be taken as 200 LPCD under ordinary conditions.
For low income groups, we can reduce demand limit upto 135 litres per capita per day.

2.Commercial/ Institutional Water Demand

On an average, 20 LPCD is usually considered as per capita demand to meet commercial and institutional demands. But this value can go up to 50 LPCD for highly commercialized cities,
For Cinemas and theatres, demand is approx. 15 LPCD and for hospitals, demand is maximum (340 to 380 LPCD).

3.Industrial Water Demand

The industrial water demand represents the water demand of any industries which are existing or likely to be started in future.
For paper industries, for 1 tonne of paper production, 200-400 Litres of water is used.
For petroleum refinery and sugar mills, per tonne production needs 1-2 litres of water.

4.Demand for Public Use

This includes water requirement for Parks, sprinkling on roads , public drinking, public toilets etc.
The amount not exceeding 5% of the total consumption of city can be considered as demand for public use.

5.Fire Demand

Following requirements must be met for Fire Demand:

Three jet stream are simultaneously thrown from each hydrant, one on the burning property and one on each adjacent property.
Discharge in each stream should not be less than 1100 L/min.
The minimum head available should be 12 to 15 metre and should be maintained for 4 to 5 hours
For a city of 50 Lakhs population, the total amount of water consumption amounts to 1 LPCD hardly, but this water should be easily available and kept always stored in service reservoirs

Kuichling's Formula for Fire Demand

6.Losses and Thefts

Water lost in leakage due to bad plumbing, theft, unauthorized water connections and other losses.
This amount is taken as 15% of total demand.

PER CAPITA Demand

It is annual AVERAGE amount of Daily water required by 1 person and includes domestic, industrial, commercial, public use, thefts, etc.

Factors Affecting Per capita demand:

Size of city
Climatic Condition
Quality of water supply
Pressure in distribution system
System of Supply

Various Type of Demand for Design

Water Demand and Population Forecasting Method

Municipal Solid Waste Management

WATER DEMAND AND POPULATION FORECASTING METHOD

2020-03-18T19:56:00.000+05:30

For designing the water supply scheme for any area or city, we must estimate the population in future for which the scheme should be designed.
The scheme once installed must fulfill the demand of projected population up to some pre determined future date.

Design Period:

As the water supply scheme includes vast costly structures such as reservoirs, dams, pumping units, distribution system, etc. which can not be replaced or modified to increase their capacities easily in later on.
Almost all components are designed to ensure that the future needs of the community gets satisfied. This future need is called Design Period.
The design period should be neither too short nor too long.

Three major factors which are responsible for growth or decline in Population are mentioned below:

Birth
Death
Migration

Population Forecasting Methods

NOTE: Generally Decades are taken as the units of Time in calculations.

1. Arithmetic Progression Method

In this method, the increase in population is assumed to be constant.

2. Geometric Progression Method (Geometric Increase Method)

In this method, the Percentage Increase in population is assumed to be constant.
Government of India Manual recommends Geometric Progressive Method because it gives the maximum value out of the other methods.

3. Incremental Increase Method

It is the combination of Arithmetic and Geometric Increase method.
Firstly, the actual increase in each decade is found.
Then,the average increment of increases is found.
By using above two calculated values, the population after n decades from present is given by:

Government of India (GOI) Manual Recommends..

Arithmetic Increase Method is used for old cities as growth rate is assumed to be constant
Geometric Progression method is used for new and younger cities as it give highest value.
Whenever there is negative rate of increase, Incremental increase method is used. It gives values in between Arithmetic progression method and Geometric Progression Method.

NOTE: There are other methods also for forecasting but this three methods are important for any exam.

Also Read:

Different type of water demand and per capita Demand

Physical water quality parameters

BIOLOGICAL WATER QUALITY PARAMETERS

2020-03-07T11:42:00.003+05:30

PHYSICAL WATER QUALITY PARAMETERS (click on it)

CHEMICAL WATER QUALITY PARAMETERS (click on it)

Types of Organics

Organics are further classified into Biodegradable and Non-biodegradable organics
Biodegradable Organics - Easily decomposed by natural agents like micro-organisms, water, oxygen, ultraviolet rays of the sun, acid rains, etc. Example - food waste like vegetable and fruit peels, dead plants and animals etc.
Non-biodegradable Organics - Cannot be broken down or decomposed by natural agents. Example - plastics, polystyrene, toxic organic chemicals, paints etc.
Biodegradable organics, in water are mostly utilized for food by micro-organisms.
Reaction in the presence of free oxygen is called aerobic reaction and reaction in the absence of free oxygen is called anaerobic reaction
Microbes are majorly classified into 3 categories -

1.Aerobic - react in the presence of free oxygen

2.Anaerobic - react in the absence of free oxygen
3.Facultative - react either in the presence or absence of free oxygen.

The most important organisms of concern are called pathogens. These are capable of transmitting diseases.
Examples are bacteria, virus, protozoa and helminths.
Pathogenic micro-organisms can be tested and counted in laboratory but with great difficulty. Hence, these tests are not performed generally in routine
The usual routine tests are generally conducted to detect and count the presence of coliforms, which in themselves are harmless but their presence or absence indicates the presence or absence of pathogenic micro-organisms.
Coliforms are non- pathogenic indicator organisms.
Escherichia Coliform (E. Coli) is the predominant member of the coliform group used in the test.

PROPERTIES OF COLIFORMS

Gram negative – forms red stain
Non-spore forming – no heat resistance
Facultative (predominantly anaerobic)
Bacillus – rod-shaped
Lactose fermenters

Note – Fermentation is a metabolic process in which sugars is converted to acids, gases or alcohol. Coliforms ferment lactose (a type of sugar) to lactic acid, CO2 etc.

TESTING OF COLIFORMS

1. Membrane Filter Technique

Water sample is poured on the sterile membrane filter.
Membrane is then put in contact with nutrients (M- endo medium) that permits the growth of only gram negative or coliform organisms. After the incubation for 20 hrs at 35ᵒC, number of visible colonies are counted and related to that of pathogens.
As per GOI manual, number of visible colonies after incubation of any 100 ml sample should be.

2.Most Probable Number (MPN) Test

MPN represents the microbial density which is most likely to be present in the water sample.
It is also called as multiple tube fermentation test & is determined by statistical methods.
3 sets of 5 tubes are taken and a solution of lactose broth is taken in each. The sample added is 10 ml, 1 ml and 0.1ml in each set respectively. These are called as standard test tubes.
After incubation at 35ᵒC for 48 hrs, all samples are checked for release of gases (CO2) by checking air bubbles in the tube.
If gases are evolved, coliforms are present.
The tubes which contain bubbles are called as positive tubes and are denoted as x-y-z.
Then referring to the standard table MPN/100ml is noted.
As per GOI Manual, MPN/100 ml for drinking water should be
Standard sample size is 10ml, 1ml & 0.1ml. If ex – 1ml, 0.1ml and 0.01ml sample is taken, then in it, coliforms will also be less, then MPN/100ml from table is multiplied by 10 to get actual values.
If more than 3 dilution samples are taken, Ex – 100ml, 10ml, 1ml, 0.1ml, 0.01ml, then consecutive 3 are taken and maximum out of them is reported as MPN/100 ml

Water Borne Disease

CHEMICAL WATER QUALITY PARAMETERS

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PHYSICAL WATER QUALITY PARAMETERS (click on it)

CHEMICAL WATER QUALITY PARAMETERS

1.CHLORIDE CONTENT

Chlorides in water are derived mostly from salt (NaCl, CaCl2 etc.), natural mineral deposits, agricultural and irrigation discharges.
Note that the salty taste is predominantly by NaCl and the rest doesn’t impart a significant salty taste.
Presence of chloride in high quantity indicates pollution of water due to sewage or industrial waste.
Test is conducted in accordance with IS 3025 (Part 32).
Chlorides are estimated by Mohr’s method (also called Argentometric Method) in which raw water is titrated against standard AgNO3 solution using Potassium Chromate (K2CrO4)as indicator.
The end point of titration is marked by appearance of brick red colour.
General Acceptable Limit is 250mg/l and in no case, it should exceed 1000 mg/l for public supply of drinking water owing to highly objectionable taste and in the absence of any alternative source.

2.NITROGEN (BASICS)

Nitrogen is most abundant in Earth’s environment as N2 gas makes up about 78 percent of the air we breathe.
Nitrogen is vital element required for the basic processes of life to make proteins, to grow, and to reproduce by all organisms.
Nitrogen is quite common and generally found in many forms in the environment.
Inorganic forms consist nitrate (NO3), nitrite (NO2), ammonia (NH3), and nitrogen gas (N2).
Organic nitrogen is found in the cells of all living things and is a component of proteins, peptides, amino acids etc.
When plants and animals die, proteins (which contain organic nitrogen) are broken down either naturally or by bacteria to form ammonia (NH3). This process is called "ammonification."
Then Ammonia is broken down by Nitrosomonas bacteria to form nitrite (NO2), which is furthur broken down by Nitrobacter bacteria to form nitrate (NO3).The conversion of ammonia to nitrate and nitrite is known as "nitrification".
The nitrates are reduced to gaseous nitrogen by the process of "denitrification". This process is performed by organisms such as fungi and the bacteria Pseudomonas. These organisms break down nitrates to obtain oxygen.

Fig: Nitrogen Cycle

3.NITROGEN CONTENT

Presence of nitrogen in water indicates presence of organic matter as decomposition of organic matter liberates nitrogen in various forms.

It occurs in the following forms –

Free Ammonia or Ammonia Nitrogen – Indicates recent pollution
Organic ammonia (Albuminoid Nitrogen) – Indicates quantity of nitrogen before decomposition has started
Nitrite – Indicates partly decomposed condition
Nitrate – Indicates old pollution i.e. fully oxidized organic matter

Free ammonia should not be more than 0.15 mg/l and it can be measured by simply boiling the water and measuring the liberated ammonia by distillation process.
Organic ammonia should not be more than 0.3 mg/l and it is measured by boiling a sample of already boiled water and adding a strong alkaline solution like KMnO4 and measuring the ammonia gas liberated.
Free ammonia + Organic ammonia = Kjehldahl Nitrogen
Nitrite (NO2) is highly dangerous as it is partially oxidized, hence its permissible limit is zero. It is measured by colour matching technique.
Nitrate (NO3) is not harmful as it is fully oxidized but too much of nitrate affects infants because it causes blue baby disease or Methaemoglobinemia.
Its concentration should not be more than 45 mg/l. It is also measured by colour matching technique.

4.FLOURIDES

Member of Halogen family & forms a greenish yellow diatomic gas (F2)
Upto 1 mg/l, it helps to prevent dental cavities. During process of formation of permanent teeth, it combines chemically with tooth enamel which results in harder, stronger teeth that are more resistant to decay.
Excess value (greater than 1.5-2 ppm) results in discolouration of teeth called mottling of teeth (infants are affected, not adults). The resulting disease is called FLUOROSIS
Hence, limit of fluoride is 1-1.5 mg/l.
Greater than 5 mg/l, it causes deformation of bones called bone fluorosis and other skeletal abnormalities.
Acceptable Limit is 1-1.5 mg/l

5. METALS

Metals are of two types i.e. toxic and non toxic
Measurement of metals is done by atomic absorption spectrophotometry.
Ca, K, Na, Fe, Mn, Zn are non toxic metals
Ar, Ba, Cr, Pb, Hg etc are toxic metals
Acceptable Limit of Zn – 5 mg/l (previously 2 mg/l)

6. SODIUM

Excess Na concentration causes bad taste and harmful for cardiac and kidney patients
It is also corrosive to metal surface and in large concentrations, it is toxic for plants
It is measured by atomic absorption spectrophotometry.

Note - Atomic Absorption Spectrophotometry (AAS) test involves quantitative determination of chemical elements using the absorption of optical radiation by atom.

7.IRON AND MANGANESE

Fe and Mn pose colour problem if present in high concentrations.
Acceptable limits are 0.3 mg/l and 0.1 mg/l for Fe & Mn respectively.
Some bacteria use iron and manganese compounds as an energy supplements.
Iron and manganese poses problem in ground water and bottom layers of lakes but not in surface water
Fe2+ forms Fe(OH)3↓
Mn2+ forms MnO2↓

8.COPPER

Its large quantity affects lungs and other respiratory organs
CuSO4 greater than 250 mg/l has laxative effect
Its limit is 0.05 – 1.5 mg/l

9.DISSOLVED GASES

CH4 is known for its explosive tendency & has a high calorific value (to be discussed in detail in sludge digestion)
H2S imparts bad taste and odour.
CO2 indicates biological activity, imparts bad taste and water becomes corrosive at high concentration

BIOLOGICAL WATER QUALITY PARAMETER ( CLICK ON IT)

PHYSICAL WATER QUALITY PARAMETERS

2020-03-04T21:19:00.005+05:30

We follow IS 10500:2012 for drinking water standards. The properties/parameters which help in asserting the quality of raw water are called Water Quality Parameters.

These parameters are classified as :-

1.Physical Water Quality Parameters

2.Chemical Water Quality Parameters (Click on it)

3.Biological Water Quality Parameters ( Click on it)

Note – There are 2 limits usually associated with these parameters namely Acceptable Limit and Cause for Rejection.

PHYSICAL WATER QUALITY PARAMETERS

The parameters which can be felt or sensed by any of our senses are referred as physical water quality parameters which are mentioned below:

Suspended Solids
Turbidity
Colour
Taste And Odour
Temperature

Types of Impurities in Water

There are two types of impurities – Organic and Inorganic. Organic compounds always composed of carbon products while most inorganic compounds do not contain carbon.

Examples –

Organic Compounds : nucleic acids, fats, sugars, proteins, enzymes, hydrocarbons, methane etc.
Inorganic Compounds : salts, metals, substances made from single elements and compounds which don't contain carbon bonded to hydrogen etc.

Almost all organic compounds contain carbon-hydrogen or C- H bonds except compounds like CCl4, NH2-CO-NH2 etc.

Note : Containing carbon is not sufficient but necessary condition for a compound to be considered organic.

1.TOTAL SOLIDS

Total Solids quantify all the solids present in water i.e. suspended and dissolved, organic and inorganic.
Measured by gravimetric method i.e. by weighing
Found out by evaporating the test sample at 104ᵒC. The weight of dry residue is Total Solid.
Represented in mg/l usually. (1 mg/l = 1 ppm (only for water))
Limits

Acceptable limit : 500 mg/l

Cause for rejection limit : 2000 mg/l

SUSPENDED SOLIDS (SS/TSS)

Sources : Suspended Solids in water comes from inorganic particle like silt, clay etc., organic particles like plant fibers, algae etc.

Measurement: Measurement is done by graviometric technique i.e. weighing.

Total Solids(TS) = SS + DS are calculated by evaporating the sample at 104ᵒC and measuring the residue.
SS is obtained by filtration and heating the residue on filter at 104ᵒC .
TDS = TS – TSS
Suspended Solids are also called as Non-Filterable Solids
Dissolved Solids are also called as Filterable Solids
Organic solids both in total and suspended form can be determined by firing the test sample and residue in muffle furnace at 600-650ᵒC.
At this temp organic solids will be vaporized leaving behind inorganic solids.
Organic fraction @600ᵒC gives Carbon dioxide + water + gases
Organics solids are also called as volatile solids and Inorganic solids are also called as fixed solids.
There must not be any suspended solids in the drinking water.

2. TURBIDITY

Turbidity is the measurement of extent by which light is either absorbed or scattered by suspended material in water. However it is not a direct quantitative measure of Suspended Solids.

Note – Suspended solids depends upon concentration whereas turbidity depends on both concentration and fineness of particles in water.

Impacts :

Disinfection of turbid water is difficult because the SS may partially shield the organisms from disinfectant.
In natural bodies, turbidity interferes with light penetration and hence with the photosynthetic reactions (which gives oxygen to the water).

Note – Turbidimeter works on the principle of measuring the interference caused by a water sample to the passage of light rays.

Limits :
Acceptable Limit : 1 NTU
Cause for Rejection : 5 NTU

3. COLOUR

Source: Colour is caused by suspended and dissolved matter in water referred as apparent colour.

After suspended matter causing colour is removed by filtration, centrifugation etc., the colour obtained is called true colour.

Measurement: Measurement of colour is done by colour matching techniques using Nesslers Tubes ( Instrument used - Tintometer).

Result is expressed in TCU (True Colour Unit) or Hazen unit where 1 TCU is equal to colour produced by 1 mg per litre of platinum in the form of chloroplatinate ions(also called as

Burgess Scale). TCU is also called as Hazen Unit.

(It is only for yellowish brown colour).

The colour testing is done within 72hrs of collection as otherwise biological or physical properties may change.

Limit : Acceptable limit is 5 TCU

Cause for Rejection is 15 TCU (previously 25)

4.TASTE AND ODOUR

Source

Taste and odour are caused by dissolved gases like Hydrogen Sulphide, Methane, Organic matter or from inorganic matter.

Measurement

Odour is generally measured by an instrument known as Osmoscope by diluting the water sample upto an extent it is hardly detectable.

Intensity of taste and odour is represented and expressed as Threshold Odour Number (TON)

It represents the dilution ratio at which odour is hardly detectable

TON = (A + B) / A where A is the volume of odorous water in ml and B is the volume of odour free water required to produce a mixture in which odour is hardly detectable.

Increase in temperature may change the taste and odour. Due to this, TON testing is done in cold water.

Limit:

Acceptable limit : 1 TON

Cause for rejection : 3 TON

Note – The substances which impart odour also produce some taste but vice versa is not true.

5.TEMPERATURE

Temperature affects the chemical and biological reactions.
An increase in 10ᵒC almost doubles the biological activity.
For water supply, the temperature should be between 10-25ᵒC

Municipal Solid Waste Management

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Municipal Solid Waste: Mixture of solid & semi-solid waste originated due to different activities in the residential & commercial establishments. Solid waste is classified as

Industrial
Domestic
Hazardous – waste that possess substantial danger immediately or over a period of time. Ex- Radioactive substance, flammable waste etc.

DOMESTIC WASTE (REFUSE)

Garbage – Biodegradable (450-900 kg/m3)
Ashes – Non-combustible (700-900 kg/m3)
Rubbish – Non-biodegradable (50-400 kg/m3)

If various materials in the waste are having different densities, the overall bulk density is calculated as follows –

Methods of Disposal

Open Dumping
Sanitary Land Filling
Composting
Incineration & Pyrolysis
Shredding & Pulverization
Barging into the sea

1.OPEN DUMPING

Very simple method in which the solid wastes collected from the city are dumped in low lying area located far off from the city.
Not an eco-friendly method.
Results in contamination of environment.
Highly unacceptable method as it gives unsightly nuisances, obnoxious odour & is a breeding place for mosquitoes & flies.

2.SANITARY LANDFILL

Refuse is carried and dumped in low lying areas under an engineered operation designed & operated in an environmentally sound manner so as to not cause any public nuisance or hazard to public health.
The refuse is dumped & compacted in layers of about 1m thickness & after the day’s work, it is covered with good earth of 15 cm thickness.
The cover is called daily cover.
Sealants are used on the surface of earth before dumping so as to prevent leaching of impurities.
Sealants used can be bitumen, asphalt, butyl chloride, vinyl chloride, bentonite slurry (drilling mud)
DDT & insecticides are spread over the daily cover to prevent mosquito and fly breeding.

Advantage:

No costly plant required
Low lying waterlogged areas & quarry pits can be put to better use
No residues or byproducts left. Hence, further disposal not required

Disadvantage:

Continuous evolution of foul gases.
Leachate (impure water percolating through the soil) is formed which may pollute the ground water.
Low lying areas may not be easily available.

3.COMPOSTING

Composting is biological disposal (segregating at source itself) of refuse in which decomposition can be carried out aerobically or anaerobically.
The end product of composting is termed as compost or manure or humus.
Composting is ecologically most acceptable method.
If composting is carried out aerobically, it is called INDORE PROCESS.
Aerobic process is completed within 2-3 months, mixing being done either manually or mechanically.
If the mixing is carried out anaerobically, it is called BANGALORE PROCESS.
Anaerobic process is completed within 5-6 months in which the refuse is kept in closed trenches
In composting, the optimum conditions are attained when Carbon/Nitrogen ratio is between 30-50.
A ratio much higher than this will slow down the decomposition by oxidizing the excess carbon to CO2.
If the ratio is lower than 30, composting will be inhibited due to low-energy supply and nitrogen will be lost both by leaching and volatilization as ammonia.

Note – In Composting, Vermi-compost is the end product of the breakdown of organic matter by an earthworm.

4.INCINERATION & PYROLYSIS

Best method for disposal of plastic & rubber
In these methods, disposal of refuse is carried out by burning it at high temperature
If burning is done in the presence of oxygen, it is termed as Incineration
If burning is done in limited or no supply of oxygen, it is termed as Pyrolysis.
This method is adopted for refuse having high calorific value
Costliest method, heavy power consumption

5.SHREDDING AND PULVERIZATION

These methods reduce the nuisance of refuse before disposal
Pulverization is based on grinding action. It is done by MACERATORS
Shredding is based upon cutting or tearing action. It is done by COMMINUTORS

6.BARGING INTO THE SEA

Disposal of refuse into sea can be done if it is disposed far off from the shore (15 to 20 km) below the water surface level (3-5 m) during the time of low tides.

Note – Biomagnification is the accumulation of toxic substances when they enter a food chain. Ex- DDT & other pesticides etc.

CLASSIFICATION OF PLASTIC

Dispersal of Air pollutants and Air Plume behaviuor

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Dispersal of the air pollutants in the atmosphere depends upon the prevailing wind, temperature & pressure conditions

With the increase in the height, temperature of the normal air decreases above the earth surface (in troposphere) & the rate at which temperature decreases with increase in height is termed as LAPSE RATE or ENVIRONMENTAL LAPSE RATE (ELR). Its value is 6.5ᵒC/km (average). Lapse rate is not constant and varies from place to place and from time to time. A Rawinsonde’s thermometer measures ELR.

The rate at which temperature of parcel of air pollutant (from automobile exhaust, chimney etc.) decreases with increase in height above the earth’s surface is termed as ADIABATIC LAPSE RATE (ALR).
[If a material changes its state (P, V or T) without any heat being added to it or withdrawn from it, the change is said to be adiabatic]
It is taken as 6.0ᵒC/km for Wet Process (Wet ALR) and 9.8ᵒC/km for Dry Process (Dry ALR)

WALR is lesser because of the heating produced by the condensation of water vapour.

Depending upon the relative magnitudes of ELR and ALR, following types of atmospheric conditions are defined –

Unstable Atmosphere
Stable Atmosphere
Neutral Atmosphere

Unstable Atmosphere

The environment become unstable for the pollutants when ELR > ALR.
This is a favourable condition which leads to rapid vertical mixing of the pollutants.
The prevailing ELR in such a condition is known as Super Adiabatic Lapse Rate, as it is more than ALR.
In diagram we can observe that at elevation of 1000 m, ELR is less than ALR which means the enviroment cools more rapidly than air pocket. Thus ELR>ALR.

Stable Enviroment

The environment is said to be stable with respect to pollutants when it doesn’t lead to their thorough vertical mixing.
Such condition occurs when ELR < ALR
It is unfavourable condition and the prevailing ELR is called as Subadiabatic Lapse Rate as it is less than ALR.

At elevation of 1000 m, the temperature of environment is more than the temperature of air pocket or parcels. or We can say that ELR< ALR.

Inversion

If temperature above the surface of the earth increases with the increase in height, this condition is termed as Inversion.

The rate at which temperature increase with the increase in height is called negative lapse rate.

Inversion is generally found when earth cools rapidly in comparison to the air surrounding it (Radiation Inversion) – Occurs in winter nights and becomes normal with the rays of the morning sun.

Inversion also exists if high pressure region is surrounded by low pressure (Subsidence Inversion).

PLUME BEHAVIOUR

Gases evolved into the atmosphere are termed as Plume and their source of emission is termed as Stack.

Depending upon the type of Environment, following types of plume are observed –

a. Looping Plume (ELR > ALR) – This type of plume is observed in Super- adiabatic Environment and is characterized by rapid downward mixing which requires the higher stacks to avoid these interferences in atmosphere.

b.Neutral Plume ( ELR = ALR ) - This type of plume is found in neutral environment and is characterized by the vertically upward rise of the pollutant into the atmosphere.

c.Coning Plume ( ELR < ALR ) - This type of plume is observed in stable atmosphere generally when wind velocity is more than 32km/h.

d.Fanning Plume - This plume is observed in inversion condition and is characterized by horizontal spread of the pollutant. Higher stacks are needed if Fanning plumes are observed.

e.Lofting Plume – This type of plume is observed if Super- adiabatic environment exist over surface inversion. This plume is characterized with minimum downward mixing as it is restrained by the inversion layer below the stack. This type of plume is generally observed in winter.

f.Fumigating Plume – This type of plume is observed when inversion condition exists over Superadiabatic Environment. It is the worst possible case of plume. Gases are never able to escape as inversion layer exists over the stack.

g.Trapping Plume – This type of plume is observed when superadiabatic environment is present between two inversion layers. In this case, pollutant are trapped in between the two inversion layer. Hence it is termed as Trapping Plume.

Air Pollution

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Biosphere can be defined as zone where all three Lithosphere, Hydrosphere and Atmosphere meets, and is capable of supporting the life.

Presence of one or more air contaminants in such concentration and for such duration that it starts affecting the life in the biosphere is called Air Pollution.

Air Pollutants are broadly classified into Primary & Secondary Pollutants:

Primary pollutants have directly identifiable origin whereas when one or more primary air pollutants react under favourable conditions, it leads to the formation of secondary pollutants.
Primary Pollutants – Oxides of Sulphur, Oxides of Carbon, Oxides of Nitrogen, Lead, Hydrocarbons etc.
Secondary Pollutants – Sulphuric Acid, Ozone, Formaldehyde, PAN

Note: Out of all Nitrogen compounds, Only NO and NO2 is considered as pollutants.

Gas Law

PV = nRT.
P in N/m2, T in Kelvin, R(Universal Gas Constant) = 8.314 kJ/mole.
The temperature of the air parcel decreases with elevation.
All gases at STP (Standard Temperature & Pressure) i.e. 0ᵒC, 1 atm occupy 22.4 litres/ mole.
The concentration of suspended particles and gaseous pollutants are expressed in µg/m3 at atmospheric temperature and pressure.

The L/mol at STP is 22.4.
The value at any other temperature and pressure can be found by – (P1V1)/T1 = (P2V2)/T2

Suspended Particulate Material (SPM)

Thousands of different solid or liquid particles suspended in air which includes soil particles, soot (black powder after burning of organic matter), lead, asbestos, sea salt, fog, mist and sulphuric acid droplets.

SPM is dangerous due to following reasons:

May contain toxic materials or material which has carcinogenic effects.
Extremely small particles can become lodged in lungs leading to bronchitis, asthma etc.

Note: Pneumoconiosis – lung disease caused due to inhalation of silica & coal dust (usually to the people working in coal mines)

Nitrogen and Sulphur Oxides

•Nitrogen Oxides

–At high temperature, Gas produced by the chemical interactions between atmospheric nitrogen and oxygen.

–Problems

Greenhouse gases
Cause difficulty in breathing

•Sulphur Oxides

–Gases produced by the chemical interactions between sulphur and oxygen

–Causes acid rain

–Originated from refineries, chemical plants, burning of fossil fuels etc.

Carbon Oxides and Hydrocarbons

•Carbon Oxides

–Carbon monoxide(CO) and carbon dioxide(CO2)

–Greenhouse gases

–Chief source is automobile exhausts

–CO is colourless, odourless, toxic gas and combines with haemoglobin to form Carboxyhaemoglobin which reduces the oxygen carrying capacity of the blood.

•Hydrocarbons

–Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH4 , C6H6 etc. )

–Some hydrocarbons are related to photochemical smog and greenhouse gases.

Ozone

•Tropospheric Ozone

–Man Made pollutant

–Present in lower atmosphere

–Secondary air pollutant

–Component of photochemical smog

•Stratospheric Ozone

–consider as Essential component which screens out UV radiation in the upper atmosphere

–Man-made pollutants (ex: CFCs) can destroy it.

Photochemical Smog

•Smog is a mixture of Smoke (respiratory problems) and Fog (reduces visibility).

•Conditions for formation of Photochemical Smog –

–Hydrocarbons

–Nitrogen Oxides

–Stagnant air (for chemicals to interact)

–Abundant Sunlight (happens during day or afternoon)

•It consists of – PAN, Ozone, CO, CO2, Formaldehyde.

CONTROLLING AIR POLLUTION

1.Electrostatic Precipitator–Smoke Stack with Electrostatic Precipitator

–Efficiency of Electrostatic Precipitator

Properties of ESPs

The gas is passed through a highly ionized zone and get electrically charged & are separated out from the gas with the help of electrostatic forces in powerful electric field
Widely used in thermal power plants, mining, iron and steel plants etc.
Quite sensitive to varying dust loading & flow rates
Wet or dry particle can be collected
99% or more efficiency can be obtained
Operated at high temperature
Maintenance is nominal & power required is more as compared to other devices

2.Gravitational Settling Chamber

– Simple to design and maintain

–Low head loss

–Requires large space, Collection efficiency is low

–Only large sized particles are separated

3.Centrifugal collector

–Simple to design and economical

–Requires less floor area

–Used for industries like cement, petroleum, asphalt etc.

–Efficiency is low for smaller particle and quite sensitive.

–Can handle large volumes of gases at high temperature temperature.

4.Fabric/Bag Filter

–Fabric Filters or Baghouses use filtration to separate dust particulates from dusty gases.

–They are highly efficient types of Dust Collecting Filters available in market and can achieve a collection efficiency of more than 99% for very fine particulates. They are cost efficient also.

–Dust-loaded gases enter the baghouse and pass through fabric bags that act as filters. The bags is in either a tube or envelope shape and made of woven or felted cotton, synthetic, or glass-fiber material.

Also Read: Dispersal of Air Pollutants and Air Plume Behaviour

Design & Detailing of Beam

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Detailing of beams and slabs reinforcements has a huge impact on strength, durability and cost optimization. Reinforcement details of RCC beam and slab should tell abut the length of main reinforcement, effective cover to reinforcement, type and number of shear reinforcement and diameter of reinforcement.

Cantilever beam

Beam is the generally horizontal reinforced members which transmit the loads (mostly of slab) to columns or to another beam. Design of beam involves sizing and finding the quantity of steel based on requirement of strength and serviceability.

The design of beam is mostly based on bending moment of beam (Calculated based on loading and support conditions). Beam is firstly design for bending moment, followed by design for shear. Then check for Deflection and Crack width are applied for ensuring safe design.
Before proceeding to design of beams, We will discuss about basic like effective span, cover, reinforcement requirements for beam in this module.

A single span beam supported on masonry wall is an example of simple supported beam. This beam deflect toward downward side throughout (thus has Sagging Moment (+ve)) and has zero moment at ends. If beam is casted monolithically with slab, then slab will act as flange and resist the bending moment. If slab is present at both sides, then beam is called as T- beam and if slab is present at only one side, then beam is called as L- beam.
If beam is continuous over a number of supports, then beam will deflect downward at centre and also try to deflect upward at supports. Thus beam has Sagging Moment (+ve)
at centre and Hogging Moment(-ve) at supports.

Effective Span

The effective span of beam is that length of beam which is susceptible to torsional buckling due to applied bending moment. It is based on different supporting conditions and calculated as shown below:

a.Simple Supported Beam

Effective span= clear span + effective depth
or
centre to centre distance between supports
whichever is lesser.

b.Continuous Beam

Case.1 If width of support < 1/12th of clear span

Effective span = Same as Simple supported beam

Case.2 If width of support >1/12th of clear span

(a). When one end is fixed and other end continuous or both continuous.

Effective span = clear span

(b). When one end is simply supported and other is continuous.

Effective span = clear span+ d/2
or
clear span+1/2th of width of support
whichever is lesser.

c.Cantilever Beam

Effective span = clear span + d/2

d.Overhanging Portion

Effective span = centre of support to free end ( clear span + 1/2th of width of support)

Size of Beam

a.Depth of beam

According to Limit state design, We always design for under reinforced section as it give early warning before collapse of any RC section under worst conditions, if happen. So it is desirable to keep the depth such that percentage of steel is around 75 percent of that required in a balance section. It also satisfy the limit state of deflection.

Thus the depth of beam is selected between 1/12th to 1/15th of span for simple supported beam and 1/15th to 1/20th of span for continuous beam. For ease, we kept the depth in multiple of 50.

b.Width of beam

The beam accommodate bars at bottom as tensile reinforcement. The width of beam should be such that bars are placed at bottom in layer with sufficient spacing and also ensure min. side cover.

Width is also kept in multiple of 50. The normal width size of beam is 200, 250, 300, 350 (all in mm). We generally chose the 230 mm as width of beam as it can easily flush with 9" thick wall.

(Note:- IS 456 also specifies that size of beam should be such that it satisfy slenderness ratio condition for lateral stability. For these purpose, min. 200 mm width of beam is recommended by IS code.)

c.Cover to Reinforcement

IS code recommends min. nominal cover to different exposure conditions as shown below:

Exposure Conditions Min. Cover(mm)

Mild 20

Moderate 30

Sever 45

Very Sever 50

Extreme 75

Reinforcement Requirement

a. Main Reinforcement

1.In Tension side of beam, the minimum numbers of bars is 2 and maximum 6 bars is used in a single layer.
2.The minimum diameter of bar to be used as reinforcement is 10 mm.
3.The minimum area of tension reinforcement shall not be less than

where Ast = area of steel reinforcement
b = width of beam
d = effective depth
fy = yield strength of steel.

4.Maximum area of tension reinforcement shall not be greater than 4 percent of gross sectional area (0.04bD).

5. Reinforcement should be of same type and of same grade.

b.Shear Reinforcement

1.These type of reinforcement should passes by outer side of tension and compression reinforcement.

2.If there is no steel bar in compression side, then atleast 2 bars of diameter 10 mm are used to support shear reinforcement.

3.The spacing of shear reinforcement should not exceed from (0.75d or 300mm, whichever is lesser).

4.Minimum shear reinforcement in form of stirrups shall greater than

5.Steel bar of diameter 6, 8, 10 or 12 mm should be used as shear reinforcement.

6. Generally two legged shear stirrups are used. But if spacing is very less, then we can use four legged stirrups as reinforcement.

Photogrammetric Survey

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Photogrammetry is the method of obtaining the information regarding the physical objects through process of creating, measuring and interpreting the photographs of that particular object.

There are two major parts of Photogrammetry-

(1). Aerial Photogrammetry and (2).Terrestrial Photogrammetry.

In first one, the photographs of the area is taken by camera mounted on airplane. In later, the photograph is taken by camera mounted on or near ground level. Terrestrial (Ground) Photography has limited use in plotting special feature of any hill or cliff feature whereas Aerial Photography has wider application in topographic survey, preliminary route survey of any highway, railway or pipeline.
In these blog, We are going to discuss about Aerial Photogrammetry:

Aerial Photogrammetry is broadly classified into two categories:

Vertical Photographs
Oblique Photographs

In vertical photographs, the axis of camera is vertical i.e. it coincides with axis line of gravity of camera. When the axis of camera is coincide with datum line, the photograph is truly vertical. But when axis of camera is titled slightly, it is called Titled photograph. The tilt is generally less than 1 degree but rarely exceeds 3 degree.
When the axis of Camera is largely inclined to vertical, then it is called Oblique photograph. The axis of camera is intentionally kept inclined.

Vertical Photograph

Vertical Photograph is already define in above paragraph.

Scale of Vertical Photograph

Scale= Map distance/Ground distance



---eq. no.1

where f = focal length of lens of camera

H= height of camera from MSL

h = height of ground from MSL

You can easily solve the numerical problems by using above equation.

Horizontal distance between two points on ground

By using scale relation (eq.no.1), We can calculate the ground co ordinates of any object and thus distance between two objects on ground.

From Point A



From Point B



And the distance AB is given by

Relief Distance in a Vertical Photograph

Relief distance is defined as lateral displacement or shift in photographic position of object due to its relief ( means elevation of object above/ below the datum line.)

If object is above datum line, then relief is outward but if object is below datum line, relief is inward.

If the object is at MSL, then Relief distance will be given by

If the object is above MSL, then Relief distance will be

where

= Distance between base of tower and MSL.

IF YOU WANT TO GET "HAND WRITTEN NOTES AND IES MASTER BOOKS FOR GATE AND IES" PLEASE CLICK ON LINK AND SUBMIT FORM TO GET LINK.

In Situ Density Test- Part 1 (Core Cutter Method)

2018-12-18T23:06:00.001+05:30

In soil mechanics, No matter what you are calculating whether it's bearing capacity of soil or stresses in soil, you encounter with a term 'Density of soil'. The density of soil is used in calculating the stresses in soil, Earth pressure beyond the Retaining wall, Dam, Embankment and Estimation of soil settlement under structural loads. It is also used in Field Compaction of soil and in many other method.
In simple language, we can defined Density of soil as ratio of Mass of soil to Volume of that soil (Mass per unit volume of soil).

Density, γ= W/V

γ= mass density of soil
W= weight of soil
V= volume of soil

For dry density we know,

where w= water content

For calculating the density of soil, there are number of field test. From which, we are going to discuss Core Cutter method.

Apparatus

Cylindrical core cutter (height=12.7 cm & internal dia= 10 cm)
Steel Rammer
Steel dolly (height= 2.5 cm & dia= 10 cm)
Spade
Balance
Oven
Knife

Procedure

Measure the height and internal diameter with the help of scale.
Weigh the core cutter.
Clean and level the place where test is going to be conducted.
Place the core cutter cylinder on the level surface and then place the steel dolly above the core cutter.
Press the core cutter (with dolly) into soil with the help of rammer till only 1-1.5 cm of dolly remains above the surface.
Remove the soil around the core cutter by spade with disturbing the soil sample and lift the core cutter.
Trim the upper and bottom surface of soil sample.
Weigh the soil sample with core cutter.
Extract the soil sample from core cutter and find the water content of soil.

Calculations and Observations

S.no.	Observation and Calculations	Readings
1	Diameter of Core cutter (Internal) (d)
2	Height of Core cutter (h)
3	Volume of Core cutter (V)
4	Mass of empty core cutter (M₁)
5	Mass of Core Cutter + Soil sample (M₂)
6	Mass of Soil (M₃ = M₂ - M₁)
7	Natural Density of Soil (γ)
8	Water Content (w)
9	Dry Density of Soil (γ)

For dry density, we can use the above mentioned formula.

Result

The dry density of soil=________ g/cm³.

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Electric Roads

2018-05-05T08:39:00.003+05:30

We have all heard of electric cars, but not of electric roads. The benefits of Electric car consist of large amount vary from environmental (100 percent emission free, promoting clean air) to financial ( lesser operating cost than a regular car). The only major drawback is the need to charge the vehicle. For long distance, Electric vehicles batteries are not suitable as heavy weight batteries can’t produce enough power and they are expensive too.

Rather than simply attempting to solve this problem with larger, heavier batteries or by adding more charging stations. Israeli startup ElectRoad design the special roads that charge your car while driving.

The company major motto is to revolutionize e- mobility and eliminate the dependency on oil. ElectRoad invests in a unique technology that powers the vehicle wirelessly from the road.

The road's working is based on simple physics that change in magnetic field around or nearby coil produces electric current in the coil without even any physical contact.

Main advantages of Electroad

No need for stopping vehicles for charging.
Sustainable approach to environment i.e. less emission.
No needs for batteries, result in lesser vehicle weight and lesser energy required.
Lesser maintenance cost.
Easy to implement.
Radiation is minimized and locally shielded for drivers and passengers safety.

Working of Electric Roads

The design of Electric Road enable them to provide enough energy to power vehicles and charge their batteries too.

As per Oren Ezer, CEO of ElectRoad's company, the electricity generated from renewable energy will be transfer to the road. Removing the battery resulting vehicles much lighter and requires less energy. Electric Roads with electric cars will cost efficient as compare to the diesel buses. Half the input price, output will be quick.

Electric Roads will induce a current in coils attached to the bottom of the cars. These technology will comes with a lot of challenges. In one approach, the coils embed and power beneath the road. Another one is such alignment with the coils on the cars which results in maximum efficiency.

The amount of energy that must be transferred during the brief moments the car oases over the coils. ElectRoad explains that the coils are switched on and off dynamically so that they don’t waste energy when cars aren’t nearby.

The flexible technology only need copper and rubber materials. The deployment of technology is quick and easy. The deployment of the technology on one kilometre of road will take only half a day, from night to morning. In the installation process, firstly an asphalt scraper digs 8 centimetre deep trench. The wireless energy charging strips will be installed in the trench and fills the trench back up with the asphalt. Smart inverters will installed on the sides of the road and provide real time communication. The electric vehicle with attached coil beneath the vehicles will receives power provided with a small air gap (approx 24 cm).

The ElectRoad has already performed successful tests of the technology, and will be demoing the electric roads on a larger scale.
ElectRoad can actually power a vehicle in real life, enabling us to replace heavy batteries with smaller batteries in the vehicles, thereby making them less expensive and lighter.

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Green Buildings- Sustainable approach to environment

2018-04-27T18:46:00.002+05:30

Green Buildings(sustainable buildings) refers to that sustainable building projects which contribute in preservation of natural environment around the project site without interfering in sole purpose of the building. It includes construction operation or techniques which promote sustainable environment during entire life cycle of the buildings i.e. from siting to design, construction, operation, maintenance, renovation and deconstruction.

Green Buildings also maintain conventional building design which mainly focus on economy, utility, durability, and comfort.

Objectives of Green Buildings

To minimize the negative impact on the environment during life cycle of a building including construction.
Construction of buildings which promote minimal use of the natural resources at the time of construction as well as operation. Green buildings highlights the resource usage efficiency and also on three R's - Reduce, Reuse and Recycle.
Promote improving Health and Productivity environment.
Efficient use of energy, Water and Other resources.
Reduce waste, pollution and degradation of environmental resources.

Fundamental Principles

Optimize Energy Use

Improving the practice for efficient energy use and transfer focus on more renewable resource of energy to meet the demands. Promoting and working toward net zero energy building practice is one of significant ways to reduce our dependence on fossil fuel-derived energy.

Protect and Conserve Water

A sustainable building should use water efficiently, and reuse or recycle water for on-site use, when feasible.

Optimize Building Space and Material Use

Dependence upon natural resources increases with increment in World's population. A well designed sustainable building focuses on use and reuse materials in the productive ways during its entire life cycle.

Structure Design Principle

Optimization of Resources has key role to play in structure design principle. Green buildings give importance to open spaces like parks, garden etc. instead of focus on development of buildings in compact space.

Waste Reduction

Waste management is a environmental challenge in present time. Green buildings minimize solid waste generation and promote recycling and reuse.

Benefits of Green Buildings

The benefits of green buildings can be divided in three categories: environment, economic and social.

Environment

Green Buildings has a positive impact on the environment (at the building or city scales) as it generate their own energy or increasing biodiversity and by using less water, energy or natural resources

The building sector has the largest potential in adoption of such practices which reduce greenhouse gas emissions considerable as compared to other major emitting sectors.

Green buildings reduce air pollution significantly in most effective ways. Lesser the use of fossil fuels, lower the air pollution contributions at the site, while reduction in electricity use results in lower air pollution associated with power plants.

Economic Benefits

Construction and Operating Costs: Green Buildings cost 10-20 percent more than conventional buildings during construction. But operating cost of green buildings is much less as it save money by minimal use of water, energy and lesser maintenance cost. Thus green buildings cost less than conventional practice during long run.

Asset Value: Research shows that the share of green buildings has increasing rapidly in real estate business as people are becoming more responsible toward preservation of environment and good health care. Greener building attract tenants easily and to command higher rents and sale prices;

Workplace Productivity and Health: The green design contribute in improvement of buildings and indoor environments which directly improve worker productivity and occupant health and well-being.

Social Benefits

Green building improve air and water quality within structures, as well as the productivity of their occupants.

With improving the indoor environmental quality of a building, Occupant health, comfort, and productivity will also improve significantly. The Green building utilize maximum daylight, has appropriate ventilation, moisture control and well controlled temperature.

Various sustainable approaches to Green building

For location, always prefer used land rather than destroying greener place or forest for location. Public transport and local market should be easily available near the site as it cut travel time as well as money.
Use of Green Roof or Cool Roof.
Use products having Energy Efficient star labels as it consumes less energy than conventional equipment.
Proper insulation of building must be provided as major part of energy which are used for cooling or heating of building is saved.
Implementation of Rain water harvesting system for collecting and use of water later.
Use of waste water treatment equipment like septic tanks. The treated effluents can further reused for watering the plantation.
Always find innovative ways which focus on 3 R's- recycle, reduce, reuse.
For construction of Green buildings, always used sustainable materials for every part of buildings like roofing materials, insulation materials, paints, other buildings materials.
Usage of energy efficient lighting system like CFL or LED.
Planting Greener near buildings as Shaded landscape protect buildings from direct sunlight. Thus helps in maintaining the temperature of building and avoid unnecessary energy consumed for cooling and heating the buildings.
Solar Panels and Solar Heaters (prefer without storage) should be used.
Proper Construction Waste management.
Always replace your old HVAC after long time of use with new, highly efficient and energy stared HVAC for heating or cooling system for building.

For any suggestion of new methods or technique, leave the comment in below.

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Different type of Pavements- Flexible and Rigid Pavement

2018-02-25T16:19:00.000+05:30

Based on the Structural behaviour, the road is generally classified into two categories: Flexible Pavement and Rigid Pavement.

Flexible Pavement

The Flexible Pavement consist of top wearing surface (mixture of bitumen or aliphatic compound and coarse aggregate) followed by sub base course -cum- drainage course. The bottom most layer of pavement is compacted soil course( has lowest stability among different course). Water bound Macadam roads is example of Flexible Pavement.

Rigid Pavement

The Rigid Pavement is those type of pavement which posses higher flexural strength and modulus of elasticity value. These pavement are generally made from Portland Cement Concrete(CC) or Reinforced Cement Concrete(RCC). Rigid pavement are generally composed of plain cement concrete slab having specified strength laid over base course.

For better understanding of these pavement type along their characteristic properties, Read the following difference between flexible and rigid road pavement:

S.No.	Flexible Pavement	Rigid Pavement
1	Load is distributed into Truncated Cone.	In case of rigid, uniform distributed load distributed due to slab action.
2	Need Subgrade compaction i.e. need good quality of material	Lesser need of compaction i.e. even use less good quality of material
3	Flexible pavement has self-healing properties due to heavier loads.	Rigid Pavement has no self-healing properties.
4	There is grain to grain distribution of load.	No grain to grain distribution. Load are transferred by flexural strength.
5	Temperature Change does not produce stresses in the pavement.	Heavy stresses are produced due to temperature change.
6	Flexible Pavement has lesser life span.	Rigid Pavement has large life span
7	Flexible Pavement have low initial cost and high maintenance cost.	Rigid Pavement have high initial cost and less maintenance cost.
8	Stage Construction is feasible.	No Stage construction is possible.
9	Flexible pavement is less economical in long run.	Rigid pavement is economical in long run.
10	Flexible pavement is lesser durable.	Rigid pavement is highly durable.
11	We can open the road for traffic after few hours.	Rigid Road takes more time for opening as time required for curing is large.
12	Flexible pavement provide poor night visibility due to black colored top.	Concrete or Rigid pavement provide higher night visibility.
13	No joints are required.	Joints are required in rigid road to allow the change in shape due to temperature change.
14	In case of flexible pavement, thickness of pavement is high as addition of sub base course for drainage.	Thickness of pavement is less.
15	The stability depends upon compaction, particle interlocking and cohesion properties.	The stability of pavement is provided by cement concrete slab by beam action.

Other type of Pavements

Interlocking Cement Concrete Block Pavement

In Interlocking cement Concrete Block Pavement(ICBP), the pavement consist of cement concrete blocks of specified size, shape and strength is laid over well compacted soil sub grade or sub base course. The gaps between the block are filled with sand and vibrated so as to provide adequate compaction.

Group Index Method- Construction of Flexible Road

2018-02-23T01:21:00.001+05:30

Group Index method is an empirical method based on the soil properties.Group index formula is used for designing the Flexible Road Pavements and its thickness. For designing the thickness of different section of road pavement, We need the value of Group Index and type of Traffic Volume.

Group Index
Group Index is an arbitrary index assigned to the soil types based on percentage fines, liquid limit and plasticity index. It helps in grading of the soils. Its value ranges from 0 to 20. The higher GI value, Poorer the sub grade soil, more the thickness of pavement. Lesser its value, Higher the grade of soil.
Group Index, GI=0.29+0.005ac+0.01bd

a= value of that portion of the material passing through 0.075mm sieve in the excess of 35% but not exceed 75% ( its value should be whole number and number from 0 to 40).
b= value of that portion of the material passing through 0.075mm sieve in excess of 15% but not exceed 55% ( its value should be whole number and ranges from 0 to 40).
c= liquid limit in excess of 40% and not more than 60%. Its value should be whole numbers and ranges from 0 to 20.
d= plasticity index exceeding 10% and not more than 30% . It ranges from 0 to 20.

Traffic Type
Traffic Volume is divided into 3 groups based on the CVPD (Commercial vehicle per day)

Traffic Type CVPD

Light <50
Medium 50-300
Heavy >300

From the below graph, we can easily calculate the value of thickness of pavement corresponding the value of Group Index and Traffic Type. In the graph, the darked line represent combined thickness of surface, base, sub base course and dotted line represent the thickness of surface and base.

(Note: These above picture is only for reference purpose)

Group index method chart

These method is based upon the physical properties of the soil and does not consider soil strength while calculating the thickness of the pavement.

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California Bearing Ratio (CBR) Test- Soil Test

2018-02-19T00:25:00.001+05:30

The California Bearing Ratio (CBR) test is a penetration test to evaluate the strength of sub grade soil or other materials like base course under the carriageway. The CBR test is the measure of resistance to the penetration of flexible pavement material or soil under the effect of standard plunger under the standard conditions.

For Modified California Bearing Ratio Method for Design of Flexible Road as per IRC37, Click here.

It is developed by California State Highway Department before the world war second. California Bearing Ratio is defined as the ratio of load(or pressure) sustained by specimen at 2.5 or 5.0 mm penetration by the load(or pressure) sustained by standard specimen at standard conditions and corresponding penetration level. It is generally represented in percentage.

CBR (in %) = (load on specimen at 2.5 mm or 5 mm penetration)/(load on standard material at corresponding level)*100

The standard load value at specified penetration value have been established by a series of test on the standard specimen of aggregate and these value is given as following:

Penetration (in mm) Standard Load(in Kg) Unit Standard Load(in Kg/ sq.cm)

2.5 1370 70
5 2055 105

Determination of CBR value in the laboratory

The CBR apparatus consist of a mould 150 mm diameter having base plate and collar, loading frame with a plunger in cylindrical shape of 50 mm diameter. A dial gauge is provided to measure the penetration value of the specimen. The CBR test can be performed on undisturbed soil sample or on remoulded soil. It can also performed on specimen in soak condition or in unsoak condition. As per IRC(Indian Road Congress) guidelines, the test should be carried out on remoulded specimen in soak conditions. Only the material which passes from 20 mm sieve should be used in these test.

The specimen in the mould is compacted to maximum dry density at Optimum Moisture Content.

Then the specimen is subjected to soaking for four days, swelling and water absorption value should be noted down. Then the surcharge weight is placed on the top of specimen and whole assembly is placed under the the plunger of the loading frame. The load value corresponding to penetration value of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 10.0, 12.5 mm is noted down and a graph between load value and its corresponding penetration value is plotted.

In the graph, there are two curves- upper curve with convexity upward and lower curve with initially concavity upward. These indicate that lower curve require necessary correction by establishing a tangent from the steepest point of lower curve. These reason behind initial concavity is:

The top layer of specimen is too soft after soaking in the water.
The top surface is uneven.
The penetration plunger of the loading machine is not vertical.

Normally, the CBR value for 2.5 mm penetration is higher than CBR value for 5 mm penetration and higher value from both values is reported as CBR value of the material. If the value at 5 mm penetration is higher than the value for penetration of 2.5 mm, then the test is repeated for the check and if same result is obtained then report these value as CBR value of material.

The CBR test is an arbitrary strength test and hence these test cannot be used to calculate the soil properties like cohesion or shear resistance.

For Modified California Bearing Ratio Method for Design of Flexible Road as per IRC37, Click here.

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Self Compacting Concrete
Transparent Concrete
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Self Compacting Concrete

2017-11-23T21:16:00.000+05:30

Self Compacting Concrete is highly flowable concrete mixture which is able to consolidate under its own weight. It also known as Self Consolidating and Flowing concrete. These type of concrete does not require the mechanical vibrator for compaction. It can reach all the possible corner of shutter without any effort.

Self Compacting Concrete does not have large amount of water. Rather it contains less amount of water than normal mix. The higher flowability can be achieved by higher proportion of fine aggregate (sand)

and use of superplasticizers and viscosity modifier agent. Polycarboxylate,Glenium C303SCC are common example of superplasticizers.

In addition to basic element used in concrete, superplasticizers and viscosity modifier agent (VMA) helps to reduce bleeding and segregation. SCC have all the necessary and desire properties and characteristics strength of normal concrete.

A well mix SCC has higher deformabitly and stability.

In comparison with normal concrete having same water-cement ratio and compacted with vibrators, SCC have slightly higher strength as no vibration gives well and improved interface with cement water paste.

Advantage

Improved labour work
Proper bond with reinforcement
Lesser requirement of skilled labour
Improved Constructablity
Superior surface finish
Improved Strength and Durability
Accelerate production and lesser the required time
Easy Pumping and Placing of Concrete
Allow the designing more complex and innovative structure
Lesser numbers of voids in concrete

But these Self compacting Concrete is littler costlier than ordinary concrete. The formwork should be such that it can withstand under the weight of liquid concrete.

Testing on Self Compacting Concrete:

1.Slump Flow and T500 test: The test is require for finding the flow ability and flow rate of concrete in absence of any obstruction. It is rapid and on-site test.

The time (in seconds) required for taking outer edge of the flowing concrete to reach an average diameter of 500 mm is noted.

If there is serious segregation, then major aggregate collect in middle spot. If there is minor segregation, then the circle the surrounded by little water-cement paste.

2. Fill box Test: The test is used to measure filling ability of self compacting concrete with aggregate of maximum nomial size of 20mm. The difference between height of concrete level gives measure. It is also called as 'Kajima Test'.

3. L Box test: L Box test is widely used for measuring the passing ability of SCC and also possibility of segregation.

The ratio of H2/H1 is called blocking ratio.

The maximum value of ratio is 1. Higher the value, higher the passing ability.

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Modern Civil Engineering

Carbon Fibre Reinforced Polymer: Retrofitting method of RCC elements

Introduction

Carbon Fibre Reinforced Polymer

Advantages:

Disadvantages:

Introduction to Intze type Water Tank and its different components

Introduction

Type of Tanks

On basis of position from ground level

On basis of shape

Intze type Tank

In-situ density of natural or compacted soils by using Sand Replacement Method

APPARATUS REQUIRED

THEORY

PROCEDURE

Determination of Bulk Density of Soil

INITIAL AND FINAL SETTING TIME OF CEMENT

Modified California Bearing Ratio Method (CBR) - IRC 37 code

Manufacturing of Portland Cement (Wet and Dry Process)

1.Wet Process:

2.Dry Process:

Different zone in the process

2. Burning Zone:

A Complete Guide: Design, Working & Benefits of Slow Sand Filter

Gravity Filtration System

Slow Sand Filters

Working of Slow Sand Filter

Cleaning of Slow Sand Filter

Advantage

Disadvantage

Slow Sand Filters only work if turbidity of incoming water is less than 50 NTU because the filter get choke very frequently on working of water having turbidity > 50 NTU, require more cleaning. Hence increase operational cost of filter.

SCREENING AND AERATION (METHOD OF WATER TREATMENT)

1.Screening

a.Coarse screens (Bar screen/ Trash racks)

b.Fine Screens

2. Aeration

Methods of Aeration

DIFFERENT TYPE OF WATER DEMAND AND PER CAPITA DEMAND

1.Domestic Water Demand

2.Commercial/ Institutional Water Demand

3.Industrial Water Demand

4.Demand for Public Use

5.Fire Demand

6.Losses and Thefts

PER CAPITA Demand

Factors Affecting Per capita demand:

Various Type of Demand for Design

Also Read:

Water Demand and Population Forecasting Method Municipal Solid Waste Management

WATER DEMAND AND POPULATION FORECASTING METHOD

Design Period:

Population Forecasting Methods

1. Arithmetic Progression Method

2. Geometric Progression Method (Geometric Increase Method)

3. Incremental Increase Method

Also Read:

Different type of water demand and per capita Demand Physical water quality parameters

BIOLOGICAL WATER QUALITY PARAMETERS

PHYSICAL WATER QUALITY PARAMETERS (click on it)

CHEMICAL WATER QUALITY PARAMETERS (click on it)

Types of Organics

PROPERTIES OF COLIFORMS

TESTING OF COLIFORMS

1. Membrane Filter Technique

2.Most Probable Number (MPN) Test

Water Borne Disease

CHEMICAL WATER QUALITY PARAMETERS

PHYSICAL WATER QUALITY PARAMETERS (click on it) CHEMICAL WATER QUALITY PARAMETERS

1.CHLORIDE CONTENT

2.NITROGEN (BASICS)

3.NITROGEN CONTENT

4.FLOURIDES

5. METALS

6. SODIUM

7.IRON AND MANGANESE

8.COPPER

9.DISSOLVED GASES

BIOLOGICAL WATER QUALITY PARAMETER ( CLICK ON IT)

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Water Demand and Population Forecasting Method

Municipal Solid Waste Management

Different type of water demand and per capita Demand

Physical water quality parameters

PHYSICAL WATER QUALITY PARAMETERS (click on it)

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