Which of the following would cause crazing (superficial cracking) on the surface of concrete?

Crazing refers to the formation of fine, shallow cracks on the surface of concrete, which can occur due to a variety of factors. The correct answer highlights that early drying of concrete, particularly due to late curing or excessive moisture on the surface, is a significant contributor to this issue.

When concrete is poured, it needs to maintain a certain moisture content for proper curing. Curing allows the concrete to hydrate and gain strength. If the surface dries too quickly — which can happen if curing is delayed (for example, if water is not applied in a timely manner) or if there are excessive amounts of water pooled on top of the surface (which may cause uneven evaporation rates) — the top layer can lose moisture before the underlying concrete has had a chance to fully hydrate. This can lead to shrinkage and, subsequently, the formation of crazing cracks. The high rate of evaporation creates tension in the surface layer as it tries to cure, which is not balanced by the lower layers that are still moist, resulting in cracks.

The other factors listed in the other choices can certainly lead to problems, but they do not directly cause crazing in the same way that the specified conditions in the correct answer do. For instance, an inadequate concrete mix could