10 compaction & finishing.ppt

8/10/2019 10 Compaction & Finishing.ppt

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Optimal Load Time


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Optimum Load Time


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CE403Construction Methodology

Compaction &

Finishing


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The Compaction Process

Increasing density of a

soil by mechanicallyforcing the soil particles

closer together,

expelling air in the void

spaces of the soil.Can be accomplished in

a few hours.

Soil

H2O

Air


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5

The Consolidation Process

Increasing density of

cohesive soilsresulting from theexpulsion of waterfrom the void

spaces in the soil.May take as long as

months, or years.

Soil

H2O

Air


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The Compaction Process

Improved Characteristic of Soil:

Increased Bearing Strength Reduced Compressibility

Improved Volume-Change Characteristics

Reduced Permeability


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Factors Affecting The Degree of

Compaction

The Soils Physical & Chemical Properties

The Soils Moisture Content The Compaction Method

The Thickness of the Soil Layer (Lift)


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The Four Basic

Compaction Forces

Stat ic Weigh t (Pressure)

Manipulat ion (Kneading) Most Effective on Plastic Soils

Impact

Low Frequency for Plastic Soils (10 Hz)

Vibrat ion Higher Frequency (80 Hz)

Effective on cohesionless soils ~ Sand & Gravel


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Optimum Moisture Content

Very Important Factor

~ the moisture at which maximum density can occur. Proctor Test: ASTM & AASHTO

Standard Proctor Test

ASTM D 698, AASHTO T-99

Modified Proctor Test

ASTM D 1557, AASHTO T-180


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Proctor Compaction Tests

Test Details Standard Modified

Diameter of Mold 4" or 102 mm 4" or 102 mm5" cut to 4.59" 5" cut to 4.59"

127 mm cut to 117 mm 127 mm cut to 117 mm

Number of Layers 3 5

Blows per Layer 25 25

5.5 lb 10 lb

2.5 kg 4.5 kg

2" 2"

51 mm 51 mm

12" 18"305 mm 457 mm

1/30 ft3 1/30 ft3

0.94 l 0.94 l

12,400 ft-lb/ft3 56,200 ft-lb/ft3

592 kJ/m3 2,693 kJ/m3

Volume of Sample

Compactive Effort

Height of Sample

Weight of Hammer

Diameter of Hammer

Height of Hammer Drop


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Modified Proctor

Standard Proctor

Zero Air Voids

Line Of

Optimums

Water Content (% Dry Weight)

DryDensitylb/cuft

Typical Compaction Test


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ModifiedProctor TestResults forVarious Soils


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Compaction Specifications

From90 to 95% of the maximum densi ty asdetermined by either the Standard o rModi f ied Procto r Test.

For Example: 95% of Standard Procto r for Embankments,

Dams, and Backfi l ls.

90% of Mod if ied Proc tor for f loor slabs on-grade.

95% (to 100% ) for pavementswith high wheelloads.


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Modified Proctor

Standard Proctor

Zero Air Voids

Line Of

Optimums

Water Content (% Dry Weight)

DryDensitylb/cuft

Typical Compaction Test

100% of Standard

Proctor

95% of Standard

Proctor


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Types of Compaction Equipment

Tamping Foot Rollers

Grid/Mesh Rollers Vibratory Compactors

Steel Wheel/Smooth Drum Rollers

Rubber Tired/Pneumatic Rollers Segmented Pad Rollers

Rammers/Tampers


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Vibratory

Compactors

Hand-

Operated


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Smooth & Padded Rollers


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Pneumatic/Tired Compactor


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Vibratory


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Water Trucks


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Equipment

Selection


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Number of Passes

Number of Pass Effect


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Number of Passes


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Estimating Compactor Production

P = Number of Passes Required

W = Width Compacted per Pass, ft

S = Compactor Speed, mi/h

L = Compacted Thickness, Lift, inE = Job Efficiency

P

ExLxSxWx16.3(CCY/h)Production


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Job Management

Lifts should be kept as thin as possible for the

most efficient compaction.

Typical Lift Specifications

5-8 for Rollers, except for Vibros & Pneums

12 for Heavy Pneumatic Rollers.

8 to 48 for Vibratory Rollers.

7 for Vibratory Rollers compacting Rock.


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Grading & Finishing


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Typical Roadway Components

PAVEMENT

BASE

SUB BASE

SUBGRADE

Compacted or Stabilized

Traffic LanesShoulder Shoulder


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Blade Positions


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Articulated Grader Positions


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Estimating Production

Efficiency

1

miSection,forSpeedAve.

miLength,SectionPassesofNo.

hTime,


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Grading Example

15.0 miles of gravel road requires reshaping & leveling.

Six passes of a motor grader will be required.

Job efficiency is 0.80

Based on operator skill, machine characteristics and

job characteristics, you estimate two passes at 4 mi/h,

two passes at 5 mi/h, and two passes at 6 mi/h for this

job.

h23.10.80

1

mph6.0

15.02

mph5.0

m15.02

mph4.0

m15.02hTime,


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Output per work-hour defines

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3%

82%

3%

12% 1. Construction productivity

2. Multi-factor productivity3. Labor productivity

4. Partial-factor productivity


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A _______ must be preceded by at

least two queue nodes

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88%

6%

0%

6% 1. Normal element

2. Arc Element3. Counter element

4. Combi element


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Moisture content is the ratio of

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9%

78%

9%

3% 1. Mass of Solids to Mass of Water

2. Mass of Water in the total volume of a soil3. Mass of Water to Mass of Solids

4. Mass of Water to Total Mass of Soil


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Given the following mass diagram, the total

volume cut for section B in 103

BCY is?

43

B

26%

7%

22%

44% 1. 75

2. 1303. 200

4. 100


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Which of the following machinery does notutilize a swing-depth factor in its production

estimates?

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6%

35%

59%

0% 1. Hydraulic Excavator

2. Shovels

3. Drag lines

4. Back hoes


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Based on the following illustration, what isthe equation for the overturning moment of a

crane?

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6%

35%

9%

50% 1. Lm(rm-f)

2. Lm(rm)3. Lm(rm-s)

4. Lm(rm-b)


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Rolling Resistance is due to

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80%

3%

0%

17% 1. Tire penetration into the traveling surface

2. Tire flexing3. Vehicle Weight

4. All of the above


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Which of the following is an advantage ofusing a scraper versus an articulated dump

truck?

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20%

77%

3%

0% 1. Better fuel efficiency

2. Longer tire life3. Faster maneuver and dump times

4. Better in poor underfoot conditions


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Consider the following standard proctor. The soil has a currentmoisture content of 4%. Specifications require minimumcompacted density of at least 98% of maximum dry density.

How much does the moisture content need to be increased?

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4%

15%

54%

27% 1. 7%

2. 3%3. 15.7%

4. 18%


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10 compaction & finishing.ppt

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