Earthworks

Question 1

3 Layers of soil (horizons)

Answer 1

Topsoil - O: Organic/humus, A: Topsoil

Subsoil - B: Subsoil

Bedrock - C: Parent material, R: Bedrock

Question 2

What is the layer of decayed matter in topsoil called

Answer 2

Humus

Question 3

3 Different types of rocks

Answer 3

Igneous - Come from magma

Sedimentary - formed from loose sediment (rocks, plants, animals) over millions of years

Metamorphic - are igneous and sedimentary rocks that have been transformed by pressure/heat.

Question 4

Soil is composed of what 3 materials?

Answer 4

Rocks of varying size

Water

Air

Question 5

Particle size for boulders

Answer 5

Anything above 200mm

Question 6

Particle size of Cobbles

Answer 6

60-200mm

Question 7

Particle size of coarse, medium, and fine GRAVELS

Answer 7

(2-60mm)

Coarse: 20-60mm

Medium: 6-20mm

Fine: 2-6mm

Question 8

Particle size of coarse, medium, and fine SANDS

Answer 8

(0.06-0.2mm)

Coarse: 0.6-2mm

Medium: 0.2-.6mm

Fine: 0.06-0.2mm

Question 9

Particle size of coarse, medium, fine SILTS

Answer 9

(0.002-0.06mm)

Coarse: 0.02-0.06mm (compacts either soft or loose)

Medium: 0.006-0.02mm

Fine: 0.002-0.006mm

Question 10

Particle size of CLAY and characteristics

Answer 10

smaller than 0.006mm

Dry lumps can be broken but not powdered between fingers.

Smooth to the touch

shrinks on drying which usually leaves cracks

compactness: soft

Question 11

Characteristics of PEAT

Answer 11

Particle size varies

Mostly plant material which remains dark brown or black

distinctive smell and low-bulk density

compactness: spongy, plastic

Question 12

What has an object reached when it stops sinking into the soil

Answer 12

Equilibrium

Question 13

A GRAVEL is made of crushed rock and sand, ranging from ___” to 1/64”

Answer 13

1” to 1/64”

Typically a 4” layer

Commonly used under asphalt parking areas and concrete slabs

PROPERLY COMPACTED “A” GRAVEL CAN BE USED UNDER THE FOOTINGS OF BUILDINGS

Question 14

Granular B GRAVEL is a blend of sand and stone ___” to 1/64”

Answer 14

6” TO 1/64”

Blend of sand and stone

Commonly used under Granular A under parking areas and concrete slabs

6”-8” layers

PROPERLY COMPACTED “B” GRAVEL CNA BE USED UNDER THE FOOTINGS OF BUILDINGS

Question 15

What Effect does too much water in the soil have on compaction?

Answer 15

Particles press apart, soupy mix? Negatively affects shear strength?

Question 16

What effect does too little water in the soil have on compaction?

Answer 16

Particles are too close together, thick mix?

Question 17

What is pit run used for?

Answer 17

Unmanufactured gravel dug out of the ground at the gravel pit

Rocks typically 6” and less

COMMONLY USED FOR A BASE FOR ROADS AND DRIVEWAYS AND SHOULD BE PLACED IN LAYERS 12” THICK OR MORE

CAN BE USED FOR A HOUSE BUT NOT LARGE BUILDINGS

Question 18

Does well graded soil composition compact better than an ungraded soil composition? Why?

Answer 18

Yes, because it is a mix of different sizes of particles, fills in all the spaces better

Question 19

What is the primary processing done at a gravel pit?

Answer 19

Rock crushing

Question 20

What does a standard proctor test determine?

Answer 20

The optimal soil moisture content for compaction for it’s bearing capacity

Question 21

What is the primary reason for sink holes to form?

Answer 21

Internal erosion, either natural or human made infrastructure failure, etc

Question 22

Why is clay not a desirable material to build on?

Answer 22

It can expand and contract with moisture

Is an “expansive soil”