trench encasement, backfill, compaction

Question 1

Class ? concrete is normally used for conduit base or top protection.

Answer 1

2A

Question 2

Class 2 concrete is normally used for trench encasement and should have a compressive strength at ? seven days after the pour.

Answer 2

2,000 psi

Question 3

The type of Portland cement that may be used during low temperatures is ?

Answer 3

high early strength

Question 4

Rebar is never used to reinforce an encasement because it will interfere with the electromagnetic field around the cables.

Answer 4

false

Question 5

According to this lesson, stones with a dimension of ? or more should be removed from the material that is to be used as backfill.

Answer 5

3”

Question 6

Backfilling and tamping alongside conduits should be performed in ? thick layers until level with the top of the conduit or duct configurations.

Answer 6

2”

Question 7

Mechanical compaction of a trench should not be started until the conduit configurations have been covered with at least ? of hand-tamped backfill.

Answer 7

12”

Question 8

Because the weight of soil and the possibility of collapsing conduits, backfill should not be allowed to “freefall” more than ? as the trench is being filled.

Answer 8

24”

Question 9

If no mechanical equipment is available to compact the soil in a trench, water compaction is a quick and easy way to ensure the soil is properly compacted.

Answer 9

false

Question 10

If a trench is to be exposed to traffic, and where the pavement will be placed directly on the compacted backfill, the backfill should be compacted to ? relative compaction and the top six inches should be compacted to ? relative compaction.

Answer 10

90% / 95%

Question 11

Dozers and loaders should not be used to compact the soil unless the conduit or encasements have ? or more of soil cover.

Answer 11

5’

Question 12

When it is necessary to work the concrete between and around closely spaced units, the concrete that is normally used for encasements is Class ?

Answer 12

2B

Question 13

When it is necessary to remove forms and open structures to traffic after the concrete has been poured, ? Portland cement should be used.

Answer 13

high early strength

Question 14

Sulfate-resisting Portland cement can withstand exposure to severe ? conditions in the soil.

Answer 14

alkali

Question 15

Conduit is subject to temperature rise as the concrete cures. The temperature rise may cause the conduit to expand slightly and this is compensated for by pouring the concrete ?

Answer 15

from the center of the run