Field & trade terms
Slump
Also called: concrete slump, slump test
Slump is the field measure of how stiff or fluid fresh concrete is. A standard cone is filled, the cone is lifted, and the amount the concrete settles is measured — a low slump means a stiff mix, a high slump a wetter, more flowable one. It is the quickest check that the concrete arriving on site matches the approved mix design, and it is run before the concrete goes in the forms, because once it is placed the window to reject a bad load is gone.
Why it matters
Slump is a proxy for water content, and water content drives strength and durability. A load that shows up far wetter than the design is a warning that water may have been added, which can quietly cut the finished strength and invite cracking and shrinkage — problems that only appear well after the pour.
Because it is measured at delivery, slump is one of the few concrete quality checks where a failing result can still stop the problem — a nonconforming load can be rejected before it is placed rather than discovered in a core test weeks later.
How it shows up on site
A slump test taken at the point of placement against the range in the mix design, recorded on the batch record with the load, and a load outside the range written up and rejected rather than placed and hoped over.
Standards it's verified against
Checklists that put slump to work
Free, field-ready checklists, each with the photo every item needs before it can be submitted.
Related terms
- HoneycombVoids in hardened concrete where the mortar did not fill around the coarse aggregate, leaving a rough, porous surface with stones showing.
- Concrete coverThe thickness of concrete between the reinforcing steel and the surface — the protective layer that keeps rebar from corroding and fire from reaching it.
- Acceptance criteriaThe stated, measurable conditions installed work has to meet before it can pass — the yardstick an inspection judges against.
- ToleranceThe allowable amount a dimension or condition can vary from the target and still be acceptable — the plus-or-minus on a spec.
- MEP (mechanical, electrical, plumbing)The mechanical, electrical and plumbing trades — the systems run through a building's structure that get inspected at rough-in and again at final.
- FirestoppingSealing openings where pipe, conduit or cable pass through a fire-rated wall or floor so the assembly's rating is restored.
Knowing the term is step one. Proving it is the job.
RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.