Concrete Technology Multiple Choice Questions and Answers

31. The horizontal d.p.c. is placed not less than150 mm above the

1. finished floor level
2. foundations
3. external ground level
4. oversite concrete

32. The maximum thickness for hardcore when used below oversite concrete is normally

1. 300 mm
2. 500 mm
3. 400 mm
4. 600 mm

33. The minimum lap for a flexible d.p.c. is

1. 50 mm
2. 75 mm
3. 100 mm
4. 150 mm

34. The number of layers in which the slump cone is filled and the number of times each layer is rodded is

1. 2; 25
2. 3; 25
3. 3; 35
4. 4; 35

35. The type of aggregate used for the manufacture of lightweight concrete blocks is

1. crushed sandstone
2. pulverised fuel ash
3. granite chippings
4. broken old bricks

36. The type of material suitable for a flexible d.p.c. is

1. blue slate
2. bituminous felt
3. engineering bricks
4. mastic asphalt

37. The use of wall plates on the top of sleeper walls is to

1. provide equal distribution of load
2. increase the floor strength
3. reduce. the number of floor joists
4. form a level bedding surface

38. The usual test for the workability of concrete is the

1. compression test
2. sieve test
3. silt test
4. slump test

39. To keep the bed joints to the required thickness, it is advisable to

1. level the work frequently
2. lay the bricks frog-uppermost
3. use the gauge staff regularly
4. take great care with bed joints

40. To prevent the occurrence of dry rot below hollow timber ground floors, it is necessary to

1. ensure all d.p.c.s are correctly placed
2. use only well-seasoned timber
3. put a damp-proof membrane below the oversite concrete
4. ensure a through draught of fresh air