Table of Contents for Construction Material Estimate Excel-
- Advantages of Construction Material Estimate
- Construction Material Estimate Excel
- Material for Plain Cement Concrete
- Material for Reinforced Cement Concrete
- Material for Masonry
- Material for Plaster
- Consideration for Wastages & Tolerance Limits of Measurement
1. Introduction for Construction Material Estimate Excel-
The estimation of the construction project is an important step during the planning phase of the project. The correct estimation is one of the steps for setting up the foundation for good project management practices to be followed.
A construction project manager has to manage the scope, cost and time. He/ She operates under these three boundaries. The scope of a project is the input for the material estimate. An increase in scope increases the types of material and their quantities.
The material estimate yields the cost required for it. The time estimation for activity also depends upon the quantity of material to be consumed. It is estimated by assessing the productivity of the resources. With the increase in material types and their quantities, the cost and time for the project increases.
The responsibility of estimating the construction material is on quantity estimator or quantity surveyor.
2. Advantages of Construction Material Estimate
The construction material estimate helps in the following-
- Estimation of cost of the material required for the project.
- Time required to consume a certain amount of material.
- Cashflow requirement by plotting the material quantity on the project timeline.
- A procurement plan is made based on the requirement of material throughout the project execution.
- Defining quality control plan for different types of material.
- Construction material storage planning.
3. Construction Material Estimate Excel-
The excel sheet for the estimation of construction material for various works such as plain cement concrete, reinforced cement concrete, brickwork and plaster is available for download through the below-given button.
4. Material for Plain Cement Concrete-
The concrete provided without reinforcement steel is called plain cement concrete. The common use of PCC is to provide a levelled base for the RCC. It prevents direct contact between the reinforcement bars and the soil.
The material used for cement concrete is cement, sand, fine & coarse aggregate and water.
The generally used grades of PCC are M7.5 & M10 as the strength requirement is low.
For some cases, where the concrete is to be filled in mass as the replacement to the loose soil, it is mixed with boulders. Such type of concrete is called Plum PCC. The addition of boulders reduces the concrete required for the same volume. The percentage of boulders range from 20-40%. The plum PCC is cheaper than the PCC.
5. Material for Reinforced Cement Concrete-
The reinforced cement concrete is the most used construction material. It is a mixture of cement, sand, fine & coarse aggregate and water, reinforced with steel bars. The steel bars can be mild steel or HYSD.
The steel bars have ribs over it that enhances the bond between it and the concrete.
The composition of the material in the concrete defines its’ strength. The grade of the concrete is designated with the letter ‘M’ followed by a number. The letter ‘M’ means ‘Mix’ and the number represents the characteristic strength of concrete in N/mm^2.
The Table 2 of IS456:2000, divides the grades of concrete into three groups-
Ordinary Concrete M10 to M20
Standard Concrete M25 to M55
High Performance Concrete M60 to M80
The constituent composition of concrete can be determined either by the ‘Nominal Mix’ or ‘Design Mix’. In Nominal Mix, the composition of concrete constituents is fixed. The % composition provides sufficient strength up to grade M20.
It is always a good practice to use the ‘Design Mix’ concrete as it is more strength & economically optimised. In the design mix, the % composition of the constituents is determined by making trial samples and testing them against the required strength for the most economical composition.
6. Material for Masonry
The masonry is done with brick, concrete blocks, stone etc. The bricks/blocks/stones are bonded together by arranging them and filling the mortar between them. The mortar can be made of lime or concrete. In, rural areas for low-cost construction, mud is also used in place of mortar.
A mortar is a mixture of a binding material (cement or lime), coarse sand and water.
The brick masonry is generally done for full brick (230mm width) and half-width (115mm width). The full brick masonry is generally measured in volume (cubic meter) and the half-brick masonry in the area (square meter).
The stone masonry is of two types- CR & RR. The Course Rubble (CR) masonry has uniform shape-size stones arranged in proper sequence. It requires highly skilled manpower and the cost is also higher.
The Random Rubble (RR) masonry utilizes the irregular shaped stone of non-uniform size. The stones are arranged in random.
7. Material for Plaster
The plaster is done over the masonry and concrete surface to provide an even surface and smooth finishing. The plaster is a mixture of binding material (cement or lime), fine sand and water.
8. Consideration for wastages and tolerance limits of measurement in Construction Material Estimate Excel-
The calculated quantities in the excel sheet are exactly as per the calculation. However, for planning the materials, the wastage of materials should be considered.
The wastage of material happens due to handling issues, storing issues, quality issues etc. The variation in the quantity planned and the quantity delivered at the site may also occur due to faulty weight or volume measurement.
The variation in the theoretical and actual weight of steel reinforcement bars arise due to the difference in tolerance limits of material size (i.e., the rolling margin of steel bars).
The following additional % of materials can be considered to accommodate the wastages and tolerance limit of measurement.
Fine & Coarse Aggregate 3.5%
Steel Reinforcement 2.5% (2% returnable and 0.5% invisible)
The acceptable wastage & variation percentage may vary as per the organisation, place, method of handling, and measurement methods etc.
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