Reviewer 5 Flashcards
Concrete contains (i)Siliceous aggregates, having higher coefficient of expansion (ii)Igneous aggregates, having intermediate coefficient of expansion (iii)Lime stones, having lowest coefficient of expansion
[ A ] i and iii [ B ] ii and iii [ C ] i and ii [ D ] i, ii and iii
D
Select the incorrect statement
[ A ] R.C.C has better fire resistance than steel
[ B ] R.C.C. structure is economical than steel structure
[ C ] Strength of concrete decreases as age increases
[ D ] R.C.C can be used for under water and marine structures
Strength of concrete decreases as age increases
Water cement ratio is the ratio of [ A ] Water to cement by weight [ B ] Water to cement by volume [ C ] Cement to water by weight [ D ] Cement to water by volume
A. Water to cement by weight
Concrete is [ A ] Weak in tension [ B ] Strong in tension [ C ] Strong in both tension and compression [ D ] Weak in compression
A] Weak in tension
The entrained air in concrete [ A ] Increases the strength [ B ] Decreases the resistance to weathering [ C ] Increases the workability [ D ] Decreases the workability
C. Increases the workability
Concrete is unsuitable for compaction by vibration if it is [ A ] Semi –plastic [ B ] Plastic [ C ] Earth moist [ D ] Dry
B. Plastic
The strength and quality of concrete depends upon (i)Grading of aggregates (ii)Shape of aggregates (iii)Surface area of aggregates (iv)Surface texture of aggregates [ A ] i, ii and iv [ B ] ii, iii and iv [ C ] i, iii and iv [ D ] i, ii, iii and iv
D
In order to avoid segregation, fresh concrete should be dropped from a height of
Less than one meter
The process of hardening of concrete in the presence of water is called
Hydration
The process of keeping the concrete structure moist is called
Curing
The separation of water or water cement mixture from the freshly laid concrete is known as
Bleeding
The continuous strain, which the concrete undergoes due to application of external loads is called
Creep
The process of conversion of plastic concrete to solid stage is called
Setting
At 28 days of curing concrete attains a strength of
90 to 95%
In a mass concrete, the aggregates occupy a space of
75%
