521. The initial setting time of lime-pozzolona, is
A. 30 minutes
B. 60 minutes
C. 90 minutes
D. 120 minutes.

522. The normal curing period for lime mortar, is :
A. one day
B. 3 days
C. 7 days
D. 10 days

523. For lime concrete,
A. slump is 50 to 75 mm
B. flexural strength at 90 days is 0.2 N/mm2
C. compressive strength at 90 days is 1.5 N/mm2
D. all the above.

524. Plaster of Paris is obtained by calcining
A. bauxite
B. gypsum
C. kankar
D. lime stone

525. For the manufacture of Portland cement, the proportions of raw materials used, are
A. lime 63% ; silica 22% ; other ingredients 15%
B. silica 22% ; lime 60%; other ingredients 18%
C. silica 40% ; lime 40%; other ingredients 20%
D. silica 70% ; lime 20% ; other ingredients 10%.

526. Good quality cement contains higher percentage of
A. Tricalcium silicate
B. Di-calcium silicate
C. Tr-calcium aluminate
D. Tetra calcium alumino ferrite

527. Initial setting of cement is caused due to
A. Tr-calcium silicate
B. Di-calcium silicate
C. Tr-calcium aluminate
D. Tetra calcium alumino ferrite.

528. Ultimate strength to cement is provided by
A. Tricalcium silicate
B. Di-calcium silicate
C. Tr-calcium aluminate
D. Tetra calcium alumino ferrite.

529. To retard the initial setting time of cement, the compound responsible, is
A. Tricalcium silicate
B. Gypsum
C. Di-calcium silicate
D. Tri calcium aluminate.

530. The compound of Portland cement which reacts immediately with water and also sets first is
A. Tr-calcium silicate
B. Di-calcium silicate
C. Tr-calcium aluminate
D. Tetra calcium alumino ferrite.

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