The knowledge about "civil engineering" provided by Er. Md Faiz Ali through this plateform is absolutely correct and verified based on practical knowledge and good experiences.

Friday, 12 July 2019

Friday, 29 December 2017

Slump Test

To determine the relative consistency of freshly mixed concrete by using Slump Test. 

 The following tests are commonly employed to measure work ability.
(a) Slump Test 
(b) Compacting Factor Test 
(c) Flow Test 
(d) Kelly Ball Test 
(e) Vee Bee Consistometer Test.

Here we will discus about Slump test. Because slump test is one of the most important test while we are determining the work ability of concrete.

Slump Test  :-
                        Slump test is the most commonly used method of measuring consistency of concrete which can be employed either in laboratory or at site of work. It is not a suitable method for very wet or very dry concrete. It does not measure all factors contributing to work ability, nor is it always representative of the place ability of the concrete.
                        The pattern of slump is shown in Fig. It indicates the characteristic of concrete in addition to the slump value. If the concrete slumps evenly it is called true slump. If one half of the cone slides down, it is called shear slump. In case of a shear slump, the slump value is measured as the difference in height between the height of the mold and the average value of the subsidence. 

Apparatus :-
                    The Slump Cone apparatus for conducting the slump test essentially consists of a metallic mold in the form of a frustum of a cone having the internal dimensions as under:  Bottom diameter : 20 cm, Top diameter : 10 cm, Height : 30 cm and the thickness of the metallic sheet for the mold should not be thinner than 1.6 mm Weights and weighing device, Tamper ( 16 mm in diameter and 600 mm length), Ruler, Tools and containers for mixing, or concrete mixer etc.

Procedure :    
  1. Dampen the mold and place it on a flat, moist, nonabsorbent (rigid) surface. It shall be held firmly in place during filling by the operator standing on the two foot pieces. Immediately fill the mold in three layers, each approximately one third the volume of the mold. 
  2.  Rod each layer with 25 strokes of the tamping rod. Uniformly distribute the strokes over the cross section of each layer. 
  3. In filling and ridding the top layer, heap the concrete above the mold before ridding start. If the ridding operation results in subsidence of the concrete below the top edge of the mold, add additional concrete to keep an excess of concrete above the top of the mold at all time. 
  4. After the top layer has been rodded, strike off the surface of the concrete by means of screeding and rolling motion of the tamping rod. 
  5. Remove the mold immediately from the concrete by raising it carefully in the vertical direction. Raise the mold a distance of 300 mm in 5 ± 2 sec by a steady upward lift with no lateral or torsional motion. 
  6. Immediately measure the slump by determining the vertical difference between top of the mold and the displaces original center of the top surface of the specimen. Complete the entire test from the start.of the filling through removal of the mold without interruption and complete it within 2½ min.
  7. If a decided falling away or shearing off of concrete from one side or portion of the mass occurs, disregard the test and make a new test on another portion of the sample. If two consecutive tests on a sample of concrete show a falling away or shearing off of a portion of concrete from the mass of specimen, the concrete lacks necessary plasticity and cohesiveness for the slump test to be applicable. 
  8. After completion of the test, the sample may be used for casting of the specimens for the future testing. 

Slump Test

measurement of slump test

Observation :
  1. The vertical difference between top of the mold and the displaces original center of the top surface of the specimen ………… mm  
  2. The pattern of slump is shown True Slump/Shear Slump/ Collapse Slump/Zero Slump.
Result :  

The slump of concrete ……….. mm indicate Low/ Medium/ High Degree of work ability


Tuesday, 19 December 2017

Quantity of Cement, Sand & Aggregate

Concrete Mix Design:-
In order to calculate amount of cement, sand and aggregate required in 1m3 of concrete , you have to know about different grades of concrete. Based on strength Different grades of concrete is classified into  M5, M7.5, M10, M15 etc., wheras M stands for Mix and the number behind M stands for characteristic Compressive strength(fck) of the concrete in 28 days when checked in direct compression test. Tthe ratio for M20 grade of concrete is 1:1.5:3 that mean 1 part of cement, 1.5 part of sand (fine aggregate) and 3 parts of aggregate (crushed stone) in volume and then batched for mixing. To know the Concrete Mix Design follow below:-
Mix Design (M) = Cement: Sand :Aggregate 

Different grades of concrete has different proportions as follows (Concrete Mix Design) :  

As Per IS456:2000 the concrete of different grades has following proportions of Cement, sand and aggregate.


Calculation of Quantities of Cement, Sand and Aggregate in 1m3 of concrete:-

Concrete Mix Design for M20 Grade Concrete:-
Now let us consider M20 grade concrete
As per IS456:2000 M20 Grade concrete proportion is  = 1 : 1.5 : 3 
We have to add all the volume to know the total volume = 1 + 1.5 + 3 = 5.5
As we know that  during concreting when we place wet concrete , it gets harden after certain standard time. Considering the same it had be decided upon by Civil design Engineers to take a factor of safety ranging from 1.54 to 1.57 to counter that shrinkage.
i.e volume of dry Concrete = 1.54 to 1.57 times Volume of wet concrete
I am Assuming 1.57 as factor of safety
So total volume of concrete required is 1.57 Cum 

Cement (Concrete Mix Design) 
Hence we require 8 bags of cement for 1 cum of concrete.
Detailed explanation for No. of bags required for 1 cum of cement

sand (Concrete mix design)

Sand usually consists of moisture content. It increases the volume of sand (bulking of sand).
For accurate calculation use dry sand or include the effect of bulking in calculation.
Hence we require 672kg of sand  for 1 cu.m of concrete.

aggregate (concrete mix design) 

Density of aggregate may go higher if void spaces decreases. 5mm aggregate has more density when compared with 20mm size of aggregate
Hence We require 1326Kg of 20mm aggregate for 1m3 of Concrete

Amount of Water Required for 1m3 of Concrete:-
For making concrete, required amount of water is added. Water quantity is depends upon the climatic factors and workability required. We generally maintain 0.35-0.50 of water cement ratio. Remember, above values  may change according to the moisture content present in sand and aggregate. 
water (concrete mix design)
Hence 200 Litres of Water is required for 1m3 of M20 Concrete
Summary: –
8 bags of cement required for 1 cu.m of M20 grade concrete. 
672 kg of Sand required for 1 cu.m of M20 grade concrete. 
1326 kg of 20mm Aggregate is required for 1 cu.m of M20 grade concrete.
200 litres of water is required for 1 cu.m of M20 grade concrete

Table for Quantity of Cement, Sand, Aggregate, Water required for Different grades of concrete :- 


Friday, 12 May 2017

Calculate the quantity of Bricks for messionory work

First of all we should assume Mortar ratio {Cement + Sand (Thickness)}

  • Suppose Mortar Ratio is  1:6   (cement=1, sand=6)

           mortar thickness = 10mm

  • Constants 
          Density of Cement = 1440 Kg/m3

          1m3 = 35.3147 ft3
  • Volume of Brick (Without Mortar) = 0.19 x 0.9 x 0.9     = 0.001359 m3
  • Volume of Brick ( With Mortar)     = 0.20 x 0.10 x 0.10 = 0.002 m3

Now We have to determine the total volume of wall for brick work.

  • Vol of wall = height * length * thickness 
To get actual volume of brick work. subtract the all window and door volume.
Then Total volume of Brick work / volume of brick (with mortar)
You will get accurate number of  brick required.

As for example
Suppose i am having a 20cm thick wall with some dimensions. And there are a gate and window is also available in design. Then we have to find the number of bricks required to built this wall.

We need  :-
  1. Total volume of wall
  2. Volume of door
  3. Volume of window
  4. Volume of brick work
  5. Volume of brick
  6. Number of brick =?

Let’s start and do all the calculation step wise.


 Total volume of a wall =   Length × Height × Width

                                  13 × 10 × 0.65617                     20cm=0.65617ft

We change width unit in to feet

85.3021 cft/ft3


Volume of door  = 
Length × Height × Width

× 3.5 × 0.65617
        We don’t have width of the door so, to determine it’s volume we use width of wall here.
  16.07646 cft/ft3


         Volume of window  Length × Height × Width

  3.5  × 3.5 × 0.65617
  8.038 cft/ft3


              Volume of brick work  = Total vol – (vol of door + vol of window)
                            85.3021 – (16.07646 + 8.038)
           85.3021 – 24.11446
     61.18764 cft/ft3


Volume of brick    = 
Length × Height × Width

19cm × 9cm × 9cm

     1539 cm3
    we have all above units in ft3 so we have to convert cm3 into ft3

 0.054349 cft/ft3      without mortar

         Volume of brick with mortar = 20cm × 10cm × 10cm
   2,000 cm3 

0.070629 cft

Finally we don almost calculations now we have to find number of bricks required to build this wall.

Number of brick required  =  vol of brick work ÷ vol of brick

61.18764 ÷ 0.070629

                                             866.32 = 867 Bricks required


Thursday, 16 February 2017

Sewage Treatment

 What is sewage treatment :-
Municipal waste water, including sewage, is treated in a multi step process before the treated water is released into the environment.

Why we do this :-
  • Water pollution can be reduced when water is treated.
  • To control/recycle utility water.
The earth has an abundance of water, but unfortunately only a small percentage (about 0.3%) is even usable by humans. The other 99.7% is in the oceans, soils, icecaps, and floating in the atmosphere.
Earth contains as
Sea+Oceans    = 96.5%
Ground water  = 1.7%
Glaciers           = 1.7%
Vapor+Air       = 0.001%
Only  2.5% of this water is freshwater.

How to treat water to make usable :-

  1. Source control.
  2. Preliminary treatment.
  3. Primary treatment.
  4. Secondary treatment.
  5. Biological treatment.
  6. Tertiary treatment.

What is waste water ?

Wastewater, also written as waste water, is any water that has been adversely affected in quality by anthropogenic (انسانی  ) influence. Wastewater can originate from a combination of domestic, industrial, commercial or agricultural activities, surface runoff or storm water, and  from sewer inflow or infiltration.

Types of waste water :-

Waste water comes in three main types.
  1. Black water
  2. Gray water
  3. Yellow water     

Black water

This is wastewater that originates from toilet fixtures, dishwashers and food preparation sinks. It is made up of all the things that you can imagine going down the toilets, bath and sink drains. They include poop, urine, toilet paper and wipes; body cleaning liquids, anal cleansing water and so on. They are known to be highly contaminated with dissolved chemicals, particulate matter and is very pathogenic.

Gray water

This is waste water that originates from non-toilet and food fixtures such as bathroom sinks, laundry machines, spas, bathtubs and so on. Technically it is sewage that does not contain poop or urine. Gray water is treated very differently from Black water and is usually suitable for re-use.

Yellow water

This is basically urine collected with specific channels and not contaminated with either black water or gray water.

Source of waste water :-

  1. Domestic.
  2. Industrial.
  3. Commercial. 
  4. Agricultural activities.
Necessity or proper of waste water :-

We consider wastewater treatment as a water use because it is so interconnected with the other uses of water. Much of the water used by homes, industries, and businesses must be treated before it is released back to the environment.

If the term "wastewater treatment" is confusing to you, you might think of it as "sewage treatment." Nature has an amazing ability to cope with small amounts of water wastes and pollution, but it would be overwhelmed if we didn't treat the billions of gallons of wastewater and sewage produced every day before releasing it back to the environment. Treatment plants reduce pollutants in wastewater to a level nature can handle.

Wastewater is used water. It includes substances such as human waste, food scraps, oils, soaps and chemicals. In homes, this includes water from sinks, showers, bathtubs, toilets, washing machines and dishwashers. Businesses and industries also contribute their share of used water that must be cleaned.

  1. Fisheries
  2. Wildlife Habitats
  3. Recreation and quality of life

What is Sewage ?

Water that is discharged after home or industrial use, and cleared away via a system of pipes leading to a waste water treatment plant.

For what purpose are sewerage systems required in the local authority area?

To prevent pollution and hazards that potentially can cause diseases, and to prevent ground water pollution.
As opposed to closed water systems that are not accessible to the public, except  when opening the tap. The sewerage systems are open and allow the entry of various objects and materials via lavatories (شوچالیوں) and other systems for discharging water after home or industrial use.
These objects and materials that are transferred together with the sewage to the treatment plants, make the treatment work difficult and cause substantial disruptions (رکاوٹ ) in the process and affect the effluent (دھار ) quality.

Catchment  of sewage :-

A catchment is the area of land surrounding a dam and the river that feeds it. Rain falling in the catchment area that isn't absorbed into the ground runs into the river and dam. The quality of the water is determined by how 'clean' the catchment area is. It is important that we take care of our catchment areas, as good water quality is important for healthy and successful communities.

Population of forecast water :-

Population is one of the most important factors for design of the water  systems, so it should be estimated, so as to know the increasing demand and ensure continuous supply to them.

population data is obtained by previous records and the rate of increase is found out and this used for further analysis, which may be by using the methods described here.

Population data can obtained by using described below :

  1. Arithmetic growth method.
  2. Geometric growth method.
  3. Curve linear method.
  4. Decline growth method.
  5. Ratio growth.
  6. Logistic method
  • Mathematically/Arithmetic growth method :

It is based on the assumption that the rate of growth of population is constant. It means that the each year population increase by the same increment.

dp/dt = Ka

Where, dp/dt is the rate of change of population.
              Ka is the constant arithmetic increment.
Ka can be determine by finding the slop of the graph of population against time. The population in the future is thus estimated.

              dP /dt P => dp / dt = Kg 

where,   Kg = Geometric Growth constant.

If P0 is the population at any time t0 and Pf is the population at time tf then,

                 ∫Pf P0 dp/p = Kg ∫ tf t0 dt = Ln (Pf/P0 = Kg (tf/t0)

           => Ln (Pf/P0 = Kg Δt

          => (Pf/P0 = (e) Kg Δt and 

                Pf = P0 (e) Kg Δt

  • Logistic method :

When the growth rate of population due to birth, death and migration are under normal situation and not subjected to extraordinary changes due to unusual situation like war, epidemics earth quakes and refugees etc. Then this method is used:

According to this method

P = P sat / (1+ ea+ bΔt), where P sat is the saturation population, of the community and a, b are constants. P sat, a and b can be determined from three successive census populations and the equations are

P sat = 2 P0 P1 P2 - P12 (P0 + P2) / (P0 P2 - P12)

 To know more about STP Step by step click HERE

Estimation of water demand :-

While estimating the water demand some factors should be considered.

As for example:- 
  1. Type of area/city.
  2. Size of the area/city.
  3. Population of the area. 
  4. Industries.
  5. Average daily water consumption.
  6. Maximum daily consumption.
  7. Maximum weekly demand.
  8. Fire water demand / fire demand.

Sunday, 12 February 2017

Steel bar weight calculation


[1]- For Round bar:

Weight in Kg  =   Diameter(mm) x Diameter(mm) x Length(meter) / 162.2

As for example:- I have a steel rod of  8mm diameter with 1 meter length.





[2]- For square and Rectangular  bar:

Weight in Kg = Width(meter) x Thickness(mm) x Length(meter) x 7.85

Chat for round steel bars


In physics the standard unit of weight is Newton, and the standard unit of mass is kilogram. On Earth, a 1 kg object weighs 9.8 N, so to find the weight of an object in N simply multiply the mass by 9.8 N. Or, to find the mass in kg, divide the weight by 9.8 N.