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Concrete & Masonryaka: slumpaka: concrete slumpaka: ASTM C143

Slump Test

In Plain English

A simple field test that measures how wet and workable fresh concrete is by seeing how much a cone-shaped sample slumps down.

Definition

A field test used to measure the consistency and workability of fresh concrete by filling a standard cone-shaped mold, removing it, and measuring the vertical drop (slump) of the concrete. Higher slump indicates a wetter, more workable mix; lower slump is stiffer. ASTM C143 governs the procedure; typical slumps range from 2 to 5 inches for structural concrete.

Why It Matters in Bidding

Slump testing is part of the concrete quality-control program, and whether it is performed by the contractor, an independent testing lab, or the supplier affects who bears the cost in a bid. Estimators on concrete-heavy jobs need to know if owner-required third-party testing is in their scope or the owner's, because misallocating that cost or ignoring rejection risk on out-of-spec loads can hurt both margin and schedule.

Example

Reviewing the specifications, the concrete estimator confirms the owner pays for independent slump and cylinder testing but notes the contractor must furnish labor to assist sampling, so a modest allowance for field coordination is added to the bid.

Related Terms

Ready-Mix ConcreteWater-Cement RatioAdmixtureCompressive Strength

Frequently Asked Questions

Owner-commissioned independent testing labs typically perform and bill acceptance testing to the owner, while the contractor furnishes access and assistance. Some specs make the contractor responsible for QC testing. Estimators must read the testing section to assign the cost correctly rather than assuming the other party covers it.
Out-of-spec concrete may be rejected before placement, causing delay while a replacement load is dispatched, or adjusted within allowable limits at the plant. Rejected loads cost time and money and can disrupt a pour sequence, which is why bidders factor placement-day risk into productivity assumptions on large pours.
Indirectly. The specified slump reflects workability needs, and achieving higher workability without weakening the mix often requires admixtures, which the supplier prices into the cubic-yard cost. Estimators should price the mix that meets both the strength and slump requirements rather than a generic baseline mix.

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