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Q: Which lime contains about 70% to 80% CaO and 20% to 30% clay?
  • A. Fat lime
  • B. Pure lime
  • C. Poor lime
  • D. Hydraulic lime
Correct Answer: Option D - Hydraulic lime–it is a product obtained by moderate burning (900ºC-1100ºC) of raw limestone which contains small proportions of clay (silica and alumina) 5-30 percent and iron oxide in chemical combination with the calcium oxide content (CaO + MgO 70-80% with MgO less than 5%). In slaking considerable care is required to provide just sufficient water and no excess, since an excess would cause the lime to harden.
D. Hydraulic lime–it is a product obtained by moderate burning (900ºC-1100ºC) of raw limestone which contains small proportions of clay (silica and alumina) 5-30 percent and iron oxide in chemical combination with the calcium oxide content (CaO + MgO 70-80% with MgO less than 5%). In slaking considerable care is required to provide just sufficient water and no excess, since an excess would cause the lime to harden.

Explanations:

Hydraulic lime–it is a product obtained by moderate burning (900ºC-1100ºC) of raw limestone which contains small proportions of clay (silica and alumina) 5-30 percent and iron oxide in chemical combination with the calcium oxide content (CaO + MgO 70-80% with MgO less than 5%). In slaking considerable care is required to provide just sufficient water and no excess, since an excess would cause the lime to harden.