Correct option is B
Rapid hardening cement:- It is the type of cement that developed a higher rate of gain of
strength and must not be confused with quick setting cement which only set quickly.
• The cement attains the strength at the age of 3 days equivalent to that attained by OPC in 7 days.
• This Higher strength in the initial stage is attributed to the higher fineness of the cement and increases the proportion of C3S (specific surface area should not be less than 3250 cm²/gm and C3S is approximate 56%).
Application:-
• Pre-fabricated construction
• Cold weather concreting
• Emergency repair work
• Pavement construction.
Other types of cement:-
Portland slag cement:- This cement is prepared by mixing granulated blast furnace slag, hard burnt
gypsum, and cement clinkers in suitable proportions. This cement offer:
• The heat of hydration of Portland slag cement is lower than OPC. Therefore, this cement can be used in mass concreting.Higher resistance against the attack of chlorides and sulfate.
• Better refinement of pore structure.
• Higher water tightness. so this cement can be used in the marine structures.
High alumina cement:- This cement is obtained by fusing a mixture, in suitable proportions of alumina and calcareous materials and grinding the resultant
product to a fine powder.
• The raw material used for the manufacture of high alumina cement is limestone and
bauxite.
• The proportion of alumina in the cement must not less than 32% and the ratio of the percentage of
alumina to that of lime is in the range of 0.85 to 1.3.
• The cement offers a higher initial setting time (3.5 hours) and a lower final setting time (5 hours), hence more time is available to work with the cement along with speedy construction.
• The cement can also resist high temperatures.
• It can resist the action of acid up to a greater extent.
• It also offers a higher rate of gain of strength.
