What does a "slump" test measure in concrete?

A slump test is specifically designed to measure the consistency and workability of fresh concrete. This test provides a visual gauge of how well the concrete will flow and compact, which is crucial for achieving proper placement and finish. It involves filling a conical mold with concrete, removing the mold, and measuring the distance the concrete slumps or settles from its original height. The greater the slump, the more workable the concrete is, indicating that it has a higher water content or is a less rigid mix.

In contrast, the other choices—weight, compressive strength, and temperature—address different properties or aspects of concrete that are assessed through other means. The weight of the concrete mix is typically evaluated through density measures, while compressive strength requires testing cured concrete samples under specific conditions. Temperature measurement involves separate tools and does not offer insight into the workability that the slump test provides. Therefore, the slump test's focus on consistency and workability is what makes it the correct answer.