What can cause a change in the slump of concrete?

The slump of concrete is a measure of its workability and consistency, which is largely influenced by the amount of water in the mix. When the water content changes, it directly affects the flowable nature of the concrete; more water generally leads to a higher slump (more workable), while less water results in a lower slump (stiffer). Proper adjustment of water content is crucial for achieving the desired strength and durability of the finished product.

In contrast, using higher quality aggregates may improve the strength and overall performance of the concrete, but it does not necessarily have a direct effect on the slump. Similarly, increasing mixing speed can impact the uniformity of the mix, but it does not inherently alter the water-to-cement ratio that fundamentally determines the slump. Adding more cement can affect the strength characteristics but does not directly adjust slump unless it is accompanied by a corresponding change in water content. Thus, changes in water content are the primary factor affecting the slump value.