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Materials & Specificationsaka: concrete mixaka: ready-mix concreteaka: cast-in-place concrete

Concrete

In Plain English

The most common building material, made by mixing cement, sand, gravel, and water, which hardens into a stone-like solid.

Definition

Concrete is a construction material composed of cement, aggregates (sand and gravel), water, and often chemical admixtures, that hardens through cement hydration into a strong, durable material. It is the most widely used construction material in the world due to its versatility, strength, and economy. Concrete can be cast into virtually any shape and is used for foundations, slabs, walls, and structural frames.

Why It Matters in Bidding

Concrete is usually one of the largest single line items on a structural bid, so small unit-price errors compound quickly across hundreds of cubic yards. Estimators must price by mix design (strength, admixtures, aggregate), placement method, and waste factor, and coordinate the concrete sub's pour schedule against weather and curing windows that directly affect the project timeline and cash flow.

Example

An estimator takes off 850 cubic yards of 4,000 psi concrete for a slab-on-grade, adds a 5 percent waste factor, and prices it per cubic yard delivered plus separate line items for pumping, finishing, and reinforcement before rolling it into the foundation scope.

Related Terms

Frequently Asked Questions

They quantify the volume in cubic yards from drawings, apply a waste factor (commonly 3 to 10 percent), then price ready-mix delivery per yard. Labor for placement and finishing, formwork, reinforcement, pumping, and testing are typically estimated as separate line items rather than bundled into the material unit price.
Specified compressive strength, mix admixtures, aggregate type, delivery distance, load size, and short-load or off-hour surcharges all move the price. Small pours, winter heating, and special performance requirements raise costs. Estimators confirm the spec section before pricing so the quoted mix matches what engineering actually requires.
Actual placed quantities exceed theoretical volume because of subgrade variation, formwork deflection, over-excavation, spillage, and rounded truck loads. Omitting waste understates the bid and erodes margin once field quantities run high. A documented waste percentage keeps the takeoff defensible and protects against quantity overruns during the pour.

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