When fly ash is added to concrete, what percentage decrease in water usage can typically be anticipated?

When fly ash is added to concrete, it can improve the workability of the concrete mix, leading to a reduction in the amount of water needed for the same level of consistency and strength. The typical anticipated decrease in water usage when fly ash is used as a partial replacement for cement is generally around 5% to 15%. This enhancement occurs because fly ash particles can fill voids within the concrete mix and improve the overall cohesiveness, which reduces the need for additional water.

In this context, the choice indicating a decrease of 1-10% suggests a lower level of water savings than is commonly observed. Water usage reductions from fly ash typically trend towards the higher percentage range, making the range of 5-15% more accurate based on industry standards and practices. This adjustment allows for improved performance characteristics of the concrete while maintaining the efficiency of hydration processes.