Reinforced cement concrete work is usually estimating under two items. The concrete work including centring and shuttering, and binding of steel bars in position is taking under one item in cu.m (cu ft). The steel reinforcement and its bending are taking under a separate item in quintal (cwt). The quantity of steel being small no deduction is making for steel from the volume of concrete. Binding wire is not taking separately but included in item of R.C.C. work.

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Centring and Shuttering

Centring and shuttering may also be taken under a separate item is sq m (sq ft). Bending and binding of steel may also be taken separately in quintal (cwt).

Steel reinforcement

Steel reinforcement is calculating as per actual requirement as laying in position including over-laps, hooks, cranks, etc. It is determining from the detail drawings. If the detail drawings are not available the steel reinforcement may be calculating approximately on the percentage basis of concrete. The density of steel may be taking as 78.5 quintal per cu m or 7.85 grams per cu m (490 lbs per cu ft). The percentage of steel reinforcement depends on the design of the structure. In absence of detail design the percentage for steel concrete may be taking approximately as given below:-

• Lintel, slabs, etc. 0.7 to 1.0%
• Beams 1.0 to 2.0%
• Columns 1.0 to 5.0%
• Foundation raft, footing, etc. 0.5 to 0.5%

For small span and light load less steel is requiring and for bigger span and heavier load greater amount of steel is requiring.

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R.C.C. Work

R.C.C. work may also be taking as complete work in cu m including steel reinforcement and centring, and shuttering, bending of steel to the requiring shape, placing and binding of steel with G.I. wire in position.

The expose surfaces of R.C.C. work are fair finish and the centring and shuttering are made in such a way as to give the surface smooth and even finish. If require thin plastering of rich cement mortar may be apply but the work of plastering is not taking separately nor the thickness of plastering is measure with the concrete.

Same principle is adopting for reinforced brick (R.B.) work but the expose surface of R.B. work is finish with 12 mm thick plastering in 1 : 2 to 1 : 3 cement mortar. The item of plastering is taking separately under separate item.

In R.C.C. work the end or side covers for steel bar may be taking as 4 cm to 5 cm. The bottom and top covers may be taking as 1.2 cm to 2 cm for slab and 2.5 cm to 5 cm for beams.

Hook and Cranked bent up bars

The length of one hook may be taking as 9 Diameter of bar and the total length of straight bar hook at both ends may be taking as L + 18 Diameter.

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Plastering usually 12 mm thick is calculating in Square meter. For walls the measurements are taking for the whole face of the wall for both sides as solid, and deductions for openings are making in the following manner that are listing in the below. And Download the excel sheet calculation of quantity of mortar and materials in Plastering.

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Important points deductions for openings in the calculations

• No deduction is make for ends of beams, posts, rafters, etc.
• For small opening up to 0.5 Square meter no deduction is made, and at the same time no additions are make for jambs, soffits and of sills of these openings.
• For openings exceeding 0.5 Square meter but not exceeding 3 Square meter deduction is make for one face only. The other face is allowing for jambs, soffits and sills which are not taking into account separately.
• For openings above 3 Square meter deduction is make for both faces of the building. The jambs, soffits and sills are taking into account and adding.

As the outer jams, etc. are much smaller than the inner ones. The deductions is usually make from the outer face. For deduction for arch opening the same principle as for masonry work.

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Basic details

Plastering of ceiling usually of 12 mm thick is computing is square meter under a separate head as this work is doing with richer mortar. For R.C.C. work usually no plastering is allowing. But for fair finish a thin plaster of rich cement mortar may be allowing which should not be taking in the measurement separately. Thin rich cement mortar plastering in R.C.C. work may also be taking under a separate item, specially in the ceiling inside room.

Calculation of quantity of mortar and materials

Area x thickness gives the quantity of mortar for uniform thickness, filling up the joints. To make up nonuniform surface of wall, this may be increase by 30% which will give wet mix mortar. To get the total dry volume of ingredient materials or mortar the wet volume may be further increase by 25%. The quantity of mortar by the sum of the numerals of the proportions and multiplying by the individual numerals.

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Calculation the quantities of cement, sand and aggregate are most important in estimating work and costing of the building . Aggregate shall be of invert materials and should be clean, dense, hard, sound, durable, non absorbent and capable of developing good bond with mortar.

Coarse Aggregate

Coarse aggregate shall be of hard broken stone of granite or similar stone, free from dust, dirt and other foreign matters. The stone ballast shall be of 20 mm size and down and all should be retain in a 5 mm square mesh. Also well grade such that the voids do not exceed 42 percent.The gauge of the stone ballast shall be as specify depending on the thickness of concrete and nature of work. For building work 20 mm gauge and for road work and mass work 40 to 60 mm gauge may be use.

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Fine aggregate

Fine aggregate shall be of course sand consisting of hard, sharp and angular grains. It also pass through screen of 5 mm square mesh. Sand shall be of standard specifications clean and free from dust, dirt, and organic matters. Sea sand shall not be use.

Cement

Cement shall be fresh portland cement of standard I.S.I. specifications. Also have the requiring tensile and compressive stresses and fineness.

Water

Water shall be clean and free from alkaline and acid matters. It suitable for drinking purposes.

Proportion

The proportion of concrete shall be 1 : 2 : 4 as cement : sand : stone : ballast by volume unless otherwise specifying. Minimum compressive strength of concrete of 1 : 2 : 4 proportion shall be 140 kg per sq cm on 7 days.

Slump

Regular slump test should be carrying out to control the addition of water. It maintain the requiring consistency. A slump of 7.5 cm to 10 cm may be allow for building work, and 4 cm to 3 cm may allow for road work.

Calculate the quantities of brick work and cement, sand and aggregates in slab

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The dimensions of brick works, length, breadth and height or depth are to be taking out from the drawing plan, elevation and section. From the study of the drawing, the building is to be imagining and pictured in the mind and the dimensions are to be taking out correctly. There is no hard and fast rule for finding out dimensions from the drawing but the dimensions are to be taking out accurately. Junctions of wall at the corners and at the meeting points of walls require special junction.

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Required Data to brick works calculation

(i). Volume of the walls.

(ii). Volume of standard brick.

(iii). Details of openings in the wall.

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