If the water-to-cement (W/C) ratio is decreased, what happens to the workability of the concrete?

When the water-to-cement (W/C) ratio is decreased, the workability of the concrete generally decreases. This is because a lower W/C ratio results in a thicker, less fluid mixture that is more difficult to mix, handle, and place. Workability refers to the ease with which concrete can be mixed, transported, placed, and finished.

As the amount of water in the mix decreases, the concrete becomes stiffer due to the reduced lubrication provided by water. This stiffness can lead to increased effort during placement, making it less workable. Lower workability can be a challenge for achieving uniform consolidation, which is essential for the structural integrity and durability of the concrete.

In summary, reducing the W/C ratio negatively impacts workability, making it harder for the concrete to flow and fill the formwork effectively. Certain measures, such as the addition of plasticizers or superplasticizers, can be taken to improve the workability of low W/C ratio mixes, but on its own, a lower W/C ratio tends to decrease workability.