Why is early finishing of concrete considered detrimental?

Early finishing of concrete can indeed be detrimental primarily because it can trap bleed water. When concrete is placed, it undergoes a process known as bleeding, where water moves to the surface as the heavier cement particles settle. If finishing operations are performed too soon, the surface may still contain excess bleed water. This trapped water can then create various issues, such as surface defects, blisters, and an inadequate bond to subsequent materials applied over the surface.

Additionally, if the finishing tools push down on the newly placed concrete while bleed water is still present, it can lead to a weak surface layer that may be prone to scaling or delaminating. Therefore, waiting until the bleed water has evaporated allows for a much more stable surface and enhances the long-term durability and integrity of the concrete.

The other potential answers do not align with proper finishing practices. For instance, enhancing surface durability or improving workability would generally require ensuring the surface is properly prepared and cured, not compromised by excess moisture. Reducing the risk of cracking is often a result of allowing proper drying and curing processes, which can be adversely affected by early finishing.