Which factor has a significant effect on the slump of concrete?

The water content in concrete is a crucial factor that significantly affects its slump. Slump, which measures the consistency and workability of freshly mixed concrete, is fundamentally tied to how much water is present in the mix. When the water content increases, it enhances the flowability of the concrete, leading to a higher slump measurement. Conversely, a reduction in water content generally results in a stiffer mix with less slump.

In practice, the water-to-cement ratio is a key consideration in concrete mixtures because it influences not only the workability during placement but also the final strength and durability of the cured concrete. Therefore, manipulating the water content is a primary method to control the slump, making it a vital consideration during the concrete mixing process.

While factors like aggregate type, air temperature, and curing time can influence the overall properties and performance of concrete, they do not directly alter the slump as significantly as water content does during mixing.