Quantity surveying and planing for cost controlling in civil engineering

QUANTITY SURVEYING BASIC BOOK FOR FRESHERS

What is 1.54 for concrete and 1.27 for mortar?

Supervision of Brick Masonry Building
In the construction of brick masonry, the following points should be observed:

1.Use bricks of good quality with uniform color, well-burnt, with specific sizes and shapes.
2.Bricks should not absorb water from the mortar. Therefore, prior to utilizing the bricks in masonry work, they should be put in water for at least two hours.
3.The frog should always point upwards while laying the bricks in masonry work.
4.Construction of a brick wall should begin from the end or corner of the structure.
5.Plumb-bob should be used frequently to check the verticality of the wall.
6.Mortar utilized must be in accordance with the specifications.
7.At the end of the work, brick masonry should have toothed end.
8.Brickbats should not be used extensively.
9.Walls of brick masonry should be raised evenly. In a single day, no wall should be raised by more than 1.5 m.
10.
The face joints should be raised to a depth of 12 to 20 mm to get appropriate pointing or plastering when the mortar is green. If plastering or pointing is not required, face joints should be struck flush and finished neatly.
11.Holdfasts for windows and doors should be embedded in brick masonry with cement mortar or concrete during the time of wall construction.
12.Curing should be done for at least two weeks for brick masonry work.
13.For performing brickwork at a greater height, single scaffolding should be used.

Calculation of Water Quantity for Concrete

As you can see from the Chart, the W/C Ratio varies from 0.4 to 0.7 depending on exposure conditions.

If we need to calculate Water quantity for concrete, first find the cement content for the volume.

If we Assume the required cement volume as 50kg,

Required amount of water = W/C Ratio X Cement Volume

Therefore, Required amount of water = 0.5 X 50 kg = 25 litres / 50 kg cement bag.

For Design mix, the W/C Ratio will depend upon the workability, strength requirements.

What is Water Cement Ratio?
Water Cement Ratio means the ratio between the weight of water to the weight of cement used in concrete mix.

Normally water cement ratio falls under 0.4 to 0.6 as per IS Code 10262 (2009) for nominal mix (M10, M15 …. M25)

We all know that water cement ratio will directly affect the strength of concrete. Either it increases the strength if used in correct proportion or decrease it.

But have you ever think about it why we are using water if it has so much difficulty?

Role of Water in Concrete
Concrete is a macro content.
It contains micro ingredients such as cement, sand, fine aggregate & Coarse aggregate. In order to acquire high strength concrete which withstands up to our desired compressive strength, We need correct proportion of admixture to combine these materials.

Here comes the Water which will initiate this chemical process by adding 23%-25% of the cement volume. This initiates the chemical process and makes 15% of water cement paste also known as a gel to fill the voids in the concrete.

Understanding Concrete Grades
Based on their strength, Concrete is classified into different grades like M5, M7.5, M10, M15, M20 etc. The letter “M” stands for “Mix” and the following number denotes the characteristic compressive strength of concrete in 28 days of curing.

For example, M20 grade concrete will achieve its compressive strength of 20 N/mm2 in 28 days after curing in water.

What is Concrete Mix Ratio?
Concrete mix ratio is a relative proportioning of cement, sand, aggregate and other materials needed to prepare different grades of concrete. For example, the prescribed Nominal concrete mix ratio of M20 concrete is 1:1.5:3, hence for every 1 part of cement, 1.5 parts of sand and 3 parts of aggregate, in volume, is needed to prepare M20 grade concrete.

1CUM=500nos Bricks

No of Bricks = Volume of 1 m3 / Volume of 1 brick So the answer is 500 no of bricks are needed in 1 m3.

Example:

Size of Modular Bricks:
Length = 19cm
Breadth = 9cm
Height = 9cm
Therefore, Volume = 19x9x9 = 0.001539 m3
Number of Bricks in 1Cum without mortar = 1/0.001539
= 649.772
= 650 nos.
Considering Mortar thickness =10mm
Size of Bricks with Mortar = 20cm x 10cm x 10cm
Volume of 1 Brick with Mortar =20x10x10 m3 ………(1)
Volume of 1Cum = 1x1x1m
= 100cm x 100cm x100cm ……….(2)
Dividing equation (2) by (1)
Number of Bricks = (100X100X100) / (20X10X10)
= 500 Nos.
Therefore, the number of Bricks in 1 CUM is 500 nos.

BBS for Circular slab....

Formula for Price Adjustment:
Pn = A + b Ln / Lo + c Mn / Mo + d En / Eo +................

where,
“Pn” is the Price Adjustment factor for the work carried out in the period “n”.

“A” is a constant or the Non-Adjustable Portion of the Price Adjustment Factor to be specified in Appendix-C to Bid, representing the Non-Adjustable Portion of the Contract Price.

“b, c, d.........” are Coefficients or weightages of the order of 0.xx (i.e., fractions having two significant digits) for each specified element of adjustment in the Contract. The sum of A, b, c, d, etc., shall be one.

“Lo, Mo, Eo........” are the Base Date Indices for the specified (adjustable) elements.

“Ln, Mn, En.......” are the Current Date Indices of the specified (adjustable) elements for the period “n”.

If “P” is the amount payable (prior to adjustment) at the rates entered in the Price Schedule of the work carried out in period “n” then, Adjusted amount payable to the Contractor for the work carried out in the period “n” shall be equal to Pn*P..

ABOUT CIVIL ENGINEER
Profession
A civil engineer is a person who practices civil engineering – the application of planning, designing, constructing, maintaining, and operating infrastructures while protecting the public and environmental health, as well as improving existing infrastructures that have been neglected.