Chapter 3 - Compacting & Finishing

Question 1

Soil compaction

Answer 1

Process of increasing density of soil by mechanically forcing soil particles closer & expelling air from void spaces in soil.

Question 2

By what is the compaction of soil specified

Answer 2

AASHTO

Question 3

What does compaction improve by improving eng properties of soil?

Answer 3

Increase bearing strength
Improve volume-change characteristics
Improve load support
Reduce compressibility
Reduce permeability

Question 4

The degree of compaction that may be achieved depends on:

Answer 4

1. Moisture content of soil
2. Compaction method employed
3. Amount of compactify effort
4. Thickness of soil layers

Question 5

4 Basic compaction forces:

Answer 5

1. Static weight
2. Manipulation (kneading)
3. Impact
4. Vibration (plate compactors weight + vibrating action)

Question 6

Proctor test

Answer 6

evaluate soils moisture density relationship under specified compaction effort

Question 7

How can max density of soil be determined by using proctor

Answer 7

Compaction tests are performed over a range of soil moisture contents.
Results are plotted as dry density vs moisture content

Question 8

Dynamic (drop cone) cone penetrometer (DCP)

Answer 8

Measure in-situ shear resistance of soil.
Comprising drop weight of 10kg
falling through 460mm driving cone of 10mm dia.

Question 9

Results of poor compaction

Answer 9

Basement/ pool cracks
Slab cracks
Pipe leakages & breaks
Foundation erosion
Under abutments erosion gullies
Utility trench settling

Question 10

Tamping foot rollers

Answer 10

Compaction drum equipped with protruding feet

Question 11

Compaction equipment types

Answer 11

Tamping foot rollers
Grid/ mesh rollers
Vibratory compactors

Question 12

Grid/ mesh rollers

Answer 12

Compactor drum made up of heavy steel mesh

Question 13

Vibratory compactors

Answer 13

Compaction action by vibration such as plate compactors/ smooth drum rollers/ tamping foot rollers

Question 14

Where is compaction confined areas

Answer 14

Inside trenches
Around foundations
Column footings

Question 15

Ground modification/
Soil stabilization

Answer 15

Process of giving natural soils enough abrasive resistance & shear strength to accommodate traffic/ design loads

Question 16

Methods of soil stabilization include:

Answer 16

Mechanical
Hydraulic
Reinforcement
Physiochemical

Question 17

Mechanical methods

Answer 17

compaction equipment
dynamic/ deep compaction
vibratory compaction

Question 18

Hydraulic methods

Answer 18

Provides faster drainage at lower cost involving placing of plastic drain tubes into soil at intervals of a few feet.

Question 19

Electroosmosis

Answer 19

Employs electrical current to speed up drainage of cohesive soils

Question 20

Reinforcement methods

Answer 20

Include confinement, inclusions, mini-piles soil nailing & stone columns

Question 21

Physiochemical methods

Answer 21

Improvement of eng properties of soil by physical & chemical admixtures (granular/ cement/ lime/ asphalt)

Question 22

Grading

Answer 22

bringing earthworks to desired shape & elevation

Question 23

Finishing

Answer 23

smoothing slopes
shaping ditches

Question 24

What control corrosion

Answer 24

seeding/ sodding

Question 25

Dynamic / deep compaction

Question 26

Vibratory compaction

Question 27

Highway/ level platform construction processes

Answer 27

Balancing
Trimming

Question 28

Balancing

Answer 28

process of cutting down high spots & filling in low spots (cut-&-fill)

Question 29

Trimming

Answer 29

Process of brining each roadway to final grade

Question 30

Motor grader

Answer 30

Most versatile piece of moving earthwork
Capable of mixing & spreading soil & admixtures to soil

Question 31

What is blade of grader called

Answer 31

moldboard (similar to blade of dozer)

Question 32

Grader is used for:

Answer 32

light stripping, grading, finishing, trimming, bank sloping, ditching, backfilling & scarifying