What does a "slump test" measure in concrete?

The slump test measures the workability or consistency of fresh concrete. This test involves filling a conical mold with concrete and then lifting the mold off, allowing the concrete to slump under its own weight. The distance the concrete slumps is measured in inches or centimeters, providing an indication of the concrete’s consistency.

A higher slump indicates a more workable mix, which is essential for ensuring that the concrete can be properly placed and compacted in the formwork. This property is critical for achieving the desired strength and durability of the finished product. Conversely, a lower slump may indicate a stiffer mix that could be difficult to work with effectively.

The other options refer to aspects that are not measured by the slump test. The temperature of the mix relates to the thermal properties and curing conditions of the concrete, while the thickness of the slab and the setting time of concrete pertain to different characteristics of concrete that are evaluated using other testing methods, such as temperature probes or time-based observations.