The correct answer is: A. Sulphate resisting cement
Sulphate resisting cement is a type of cement that is resistant to the effects of sulphates in water. It is used in concrete and mortar that will be exposed to sulphate-rich environments, such as canals, sewers, and foundations.
Sulphates can attack concrete and mortar, causing it to deteriorate and crumble. This is because sulphates react with the calcium in the cement, forming calcium sulphate crystals. These crystals can grow and expand, causing the concrete or mortar to crack and break.
Sulphate resisting cement contains additives that help to prevent this reaction from happening. These additives include ground granulated blast furnace slag, fly ash, and silica fume. These materials react with the sulphates in the water, forming harmless compounds that do not damage the concrete or mortar.
Sulphate resisting cement is available in both ordinary Portland cement (OPC) and high-early strength Portland cement (HSPC) forms. OPC is the most common type of cement, while HSPC is a more expensive type of cement that sets and hardens more quickly.
Sulphate resisting cement is used in a variety of applications, including:
- Canal linings
- Sewer construction
- Foundations
- Concrete pipes
- Concrete blocks
- Concrete slabs
When choosing a cement for a sulphate-rich environment, it is important to select a cement that is specifically designed for this purpose. Sulphate resisting cement will provide the best protection against the damaging effects of sulphates.
The other options are incorrect because:
- Rapid hardening cement is a type of cement that sets and hardens more quickly than ordinary Portland cement. It is used in applications where early strength is required, such as precast concrete.
- Quick setting cement is a type of cement that sets and hardens very quickly. It is used in applications where immediate strength is required, such as emergency repairs.
- Pozzolana cement is a type of cement that is made from a mixture of Portland cement and pozzolana. Pozzolana is a volcanic ash or other siliceous material that reacts with lime to form cementitious compounds. Pozzolana cement is used in applications where high strength and durability are required, such as concrete dams and bridges.