Slow setting increases the risk that an unset surface could be damaged by which condition?

Slow setting increases the risk that an unset surface could be damaged by which condition?

• A. Rain
• B. Sun
• C. Wind
• D. Snow

Answer: (A)

When concrete is still plastic and setting slowly, its surface is soft and vulnerable to water. Rain can wash away cement paste and fine materials from the surface before the mix gains strength, creating laitance, a rough or dusty finish, and overall weaker surface so it can be damaged more easily. The other conditions don’t cause this direct washing effect: sun and wind mainly affect drying and curing without washing away the surface, and snow involves moisture and freezing cycles but Rain is the immediate damaging factor for an unset surface.

When concrete is still plastic and setting slowly, its surface is soft and vulnerable to water. Rain can wash away cement paste and fine materials from the surface before the mix gains strength, creating laitance, a rough or dusty finish, and overall weaker surface so it can be damaged more easily. The other conditions don’t cause this direct washing effect: sun and wind mainly affect drying and curing without washing away the surface, and snow involves moisture and freezing cycles but Rain is the immediate damaging factor for an unset surface.