What does ASTM C143 standard test method measure?

The ASTM C143 standard test method specifically measures the slump of hydraulic-cement concrete, which is an important aspect of concrete workability. The slump test evaluates the consistency and flow of freshly mixed concrete by determining how much a cone of concrete settles or "slumps" when the cone is removed. This measurement provides insight into the concrete's workability, helping engineers and construction professionals assess whether the concrete will meet the required specifications for a particular application.

While the other options touch on related aspects of concrete, they do not directly pertain to what ASTM C143 measures. For instance, the density of fresh concrete pertains to its mass per unit volume, workability encompasses the ease with which concrete can be mixed, placed, and finished but is evaluated through tests like the slump, and setting time relates to how quickly the concrete begins to harden, which is assessed by different methods. Therefore, the focus of ASTM C143 is squarely on slump, making it the correct choice.