What measurement indicates the workability of concrete?

The workability of concrete is best indicated by the slump test results. This test measures the consistency and flow characteristics of freshly mixed concrete. The slump test involves filling a conical mold with concrete, lifting the mold away, and observing how much the concrete settles or "slumps." A higher slump value indicates greater workability, meaning the concrete is more fluid and easier to place and work with. Conversely, a low slump indicates stiffer concrete that may be more difficult to handle and compact.

Vibrational frequency, while important for understanding the behavior of concrete under vibration, does not directly measure workability. Thermal conductivity relates to the ability of a material to conduct heat and does not provide insights into the handling characteristics of concrete. The volume of air voids can influence overall strength and durability but does not directly indicate how easy the concrete is to manipulate during placement. Thus, slump test results are the standard measure used in practice to assess workability.