Question

Which of the below would prevent surface scaling of concrete?

1) Super plasticizer
2) Calcium chloride
3) Air entrainment
4) Corrosion inhibitors

Answer 1

Air entrainment is known to prevent surface scaling of concrete by introducing tiny air bubbles into the mixture, which help to manage the effects of freezing and thawing. Other admixtures like super plasticizers, calcium chloride, and corrosion inhibitors serve different purposes and are not primarily used to prevent scaling.

Step-by-step explanation:

To prevent surface scaling of concrete, which is the peeling off or flaking of the surface layer, certain admixtures can be used in the concrete mix. Among the options provided, air entrainment is known to prevent surface scaling. The air-entrainment process involves the inclusion of tiny air bubbles within the concrete, which helps to control the expansion and contraction due to temperature changes that can cause scaling. These air bubbles provide space for water to expand when it freezes, preventing cracking and scaling as a result.

On the other hand, admixtures such as super plasticizers are used to improve workability without adding more water, which can weaken the concrete mixture. Calcium chloride is commonly used as an accelerating admixture to speed up the curing process, especially in cold weather, but it does not protect against scaling and can even lead to corrosion of steel reinforcement. Lastly, corrosion inhibitors are added to concrete to protect the reinforcing steel from corrosion, not specifically to prevent surface scaling.