Correct Answer: A. ferrous sulphate
Solution:
Boiling sawdust in a solution of ferrous sulphate (also known as iron(II) sulfate) is a method used to make it more fire-resistant and less susceptible to rot and decay. This chemical treatment effectively renders the organic material more inert, making it suitable for use in composite building materials like lightweight concrete or insulation boards.
Correct Answer: C. 11.7 to 14.4
Solution:
Thermocol, which is Expanded Polystyrene (EPS), is a lightweight insulation material. Its compressive strength is a critical property for applications where it might be subjected to load, such as under flooring. The strength varies significantly based on the density of the material. Higher density EPS provides greater compressive strength. The specified range of 11.7 to 14.4 N/mm² corresponds to very high-density grades of thermocol.
Correct Answer: C. Petroleum product
Solution:
Bitumen is a black, sticky, and highly viscous liquid or semi-solid form of petroleum. It is obtained as a residual product in petroleum refineries after the lighter fractions like gasoline and diesel are removed. Due to its excellent waterproofing and binding properties, it is widely used in road construction (as asphalt) and roofing.
Correct Answer: D. All option are correct
Solution:
Bonding admixtures are used to enhance the bond between hardened concrete and fresh concrete, or between concrete and other materials. These admixtures are typically water emulsions of various organic polymers. This category includes natural rubber (latex), synthetic rubbers (like Styrene Butadiene Rubber or SBR), and other organic polymers (like Polyvinyl Acetate or PVA). Therefore, all the listed materials can be used to create bonding admixtures.