Question

In curing cement plasters water is sprinkled from time to time. This helps in :

• A. keeping it cool
• B. developing interlocking needle-like crystals of hydrated silicates
• C. hydrating sand and gravel mixed with cement
• D. converting sand into silicic acid

Answer 1

Answer: (B)

developing interlocking needle-like crystals of hydrated silicates

Answer 2

$CaSO _{4} \cdot \frac{1}{2} H _{2} O +1 \frac{1}{2} H _{2} O \stackrel{\text { Setting }}{\longrightarrow}$ $\underset{\text{Gypsum (orthorhombic)}}{{CaSO _{4} \cdot 2 H _{2} O}} \stackrel{\text { Hardening }}{\longrightarrow} \underset{\text { Gypsum monoclinic)}}{{ CaSO _{4} \cdot 2 H _{2} O }}$