Which factor is NOT controlled by the amount of water per sack of cement?

The amount of water per sack of cement significantly affects various properties of concrete. Set up speed, workability, durability, and strength are all influenced by the water-to-cement ratio.

However, the factor that is not directly controlled by the amount of water is the set up speed. This refers to how quickly the concrete begins to harden after mixing. While the water content does influence the overall hydration process and can indirectly affect how quickly the concrete changes from a plastic to a solid state, the set up speed is more closely related to factors such as temperature, the type of cement used, and the presence of accelerators or retarders in the mix.

In contrast, workability is directly affected by the water used, as it influences how easily the mix can be manipulated and placed. Durability and strength are also significantly impacted by the water-cement ratio, as too much or too little water can compromise the structure and permanence of the cured concrete.