lesson 2 - CTQP Home Page Level 2/Student lesson...Student Manual Lesson – 2 Density Theory Version 1.0‐ 1/15 2‐14 2-13 MODIFIED PROCTOR STANDARD PROCTOR Method typically used

Student Manual Lesson – 2 Density Theory

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Lesson 2

2-1


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• Describe the difference between compaction and densityand wet & dry density

• Calculate unit weight

• Describe the Proctor and LBR Tests and their use

• Identify and describe material classifications forembankment construction

Learning Outcomes


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What is the difference between

COMPACTION & DENSITY

Terminology

The contractor uses compaction, (a process) to achieve density (a product). Compactive effort is a measure of the mechanical energy applied to a soil mass. In the field, compactive effort is the number of passes or coverages of the roller of a certain type and weight on a given volume of soil


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Wet Density vs. Dry Density

Wet Density = Total Density= (Total Weight)/(Total Volume)= (Solids+Water+Gas)/(Total Volume)

Dry Density = Dry Weight / Total Volume= (Solids+Gas)/(Total Volume)= (Solids)/(Total Volume)

Terminology

Wet Density – the weight of soil and water occupying a unit volume Dry Density – the weight of just the soil solids occupying a unit volume


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DENSITY = WEIGHT / VOLUME

VOLUME = H x L x D

DENSITY = W / (H x L x D) L

D

W

H

Density

Density is the ratio of the mass of a substance to its volume, expressed, for example, in units of grams per cubic centimeter or pounds per cubic foot. The density of a pure substance varies little from sample to sample and is often considered a characteristic property of the substance. Density often is taken as an indication of how “heavy” a substance is. Iron is denser than cork, since a given volume of iron is more massive (and weighs more) than the same volume of cork. It is often said that iron is “heavier” than cork, although a large volume of cork obviously can be more massive and thus be heavier (i.e., weigh more) than a small volume of iron. Weight is the measure of the force of gravity on a body. Since the weights of different bodies at the same location are proportional to their masses, weight is often used as a measure of mass. However, the two are not the same; mass is a measure of the amount of matter present in a body and thus has the same value at different locations, and weight varies depending upon the location of the body in the earth's gravitational field (or the gravitational field of some other astronomical body). A given body will have the same mass on the earth and on the moon, but its weight on the moon will be only about 16% of the weight as measured on the earth. One pound of weight, or force, is the force necessary at a given location to accelerate a one-pound mass at a rate equal to the acceleration of gravity at that location (about 32 ft per sec ).


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CLASS PROBLEM

2 ft.

SCALE

5 ft.3 ft.

Weight = 200 lbs.

What is the density of the cube?

Exercise

DENSITY = W / V

Math Problem Work Area


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Compaction is considered a ________ when compared to density.

Density is considered the _______ when compared to compaction.

Learning Outcomes


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Wet density is the weight of _________ occupying a unit volume.

Dry density is the weight of _________ occupying a unit volume.

Learning Outcomes


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What does A represent?

What does B represent?

DR

Y

DE

NS

ITY

% MOISTURE

Proctor Test Curve

B

A

Theory


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Just Right

Maximum Density (B)at

Optimum Moisture Content (A)

100%

98%

TargetArea

B

A

DryDensity

(pcf)

% Moisture

Can the Contractor achieve 98% outside the dashed lines?

Where will it be easiest for the Contractor to achieve density?

Theory


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Which of these two is affectedmore by water?

CLAYEY SOIL

PCF

Increasing Moisture

SANDY SOIL

PCF

Increasing Moisture

Moisture Sensitivity of Soils


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FM 1 T-180 - Moisture Density Relations of Soils Using 10-lb. (4.54-kg) Rammer and 18-inch (457-mm) Drop

AASHTO T 99 - Moisture Density Relations of Soils Using 5.5-lb. (2.5-kg) Rammer and 12-inch (305-mm) Drop

STANDARD PROCTORMODIFIED PROCTOR

DIFFERENCES

• Rammer Weight - 10 lb.• Drop Height - 18 inches• Use spacer disc in mold• Use 6 inch molds• 56 blows/layer; 5 layers

• Rammer Weight - 5.5 lbs.• Drop Height - 12 inches• No spacer disc in mold• Use 4 inch molds• 25 blows/layer; 3 layers

Maximum Density (Proctor)

The FDOT uses two types of Moisture Density Relation tests: Standard - AASHTO T-99, which employs the use of a 5.5 lb. rammer dropped from a height of 12 inches. Specimens are prepared in 4 inch molds. NOTE: This is the method typically used for obtaining Proctor values on embankment and structure backfill materials. Modified - FM 1 T-180, which employs a 10 lb. rammer dropped from a height of 18 inches. Specimens are prepared in 6 inch molds and a spacer disk used in the bottom of the mold. NOTE: This is the method typically used for obtaining Proctor values for project base, subgrade and MSE wall materials. As road construction equipment and methods improved, it became apparent that construction methods were outdistancing testing methods. In an effort to have Proctor testing be more representative of what was being done in the field, the Modified Proctor was adopted by the FDOT. The Modified Proctor requires substantially more effort in the compaction process than the Standard method.


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STANDARD PROCTORMODIFIED PROCTOR

Method typically used on FDOT projects for base, subgrade and MSE wall backfill materials.

Method typically used on FDOTprojects for embankment &structure backfill materials.

Proctor Applicability

Generally, requirement is98% of Maximum Density(some isolated cases 95%,such as MSE Walls).

Generally, requirement is100% of Maximum Density(some isolated cases 95%,such as plastic and metalpipe).


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PURPOSE OF TEST

The Limerock Bearing Ratio Test isuseful for determining whether limerockand other soils used for base andsubgrade, meet the minimum strengthrequirements in the plans.

Limerock Bearing Ratio (LBR)

WHAT IS THE LBR?

The ratio of the bearing capacity of thematerial being tested to the bearingcapacity of reference limerock

The standard penetration resistance for a typical crushed limerock in Florida has been standardized to 800 psi. The LBR result is expressed as a percent, without the percent sign. The LBR test is a Florida revision to the California Bearing Ratio test procedure.


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LBR VARIES WITH THEMOISTURE AT THE TIME OFCOMPACTION.

.BEARING CAPACITY of MATERIAL_LBR = x 100(REFERENCE LIMEROCK) 800 psi

LBR

% MOIST

7 8 9 10 11

20

40

6080

200

100

10

LBR vs. % MOISTURE



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15

20

304050

100

150200

L.B

.R.

AT 0

.1”

PEN

ETR

ATIO

N

WATER CONTENT, %

DRY

UN

IT W

T. (P

.C.F

.)

6% 7% 8% 9% 10%125

126

127

128

129

130

MOLD NO.

WATER (C.C.)

WET WT. + MOLD (GM)

WET WT. + MOLD (LBS.)

WT. OF MOLD (LBS.)

WET WT. (LBS.)

WET UNIT WT. (LBS./C.F.)

DRY UNIT WT. (LBS./C.F.)

LBR

BEGIN SOAK

END SOAK

TIME OF TEST

CAN NO.

CAN + WET SOIL (GM)

CAN + DRY SOIL (GM)

WT. WATER (GM)

WT. CAN (GM)

WT. DRY SOIL (GM)

MOISTURE CONTENT (%)

DATE COMPACTED

MOISTURE DETERMINATION

2036%

1178925.9915.9010.09134.5

9644.9608.836.176.6532.26.8


81125.9


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1. What is the Maximum Density?

2. What is the Optimum Moisture?

3. What is the Moisture Range for 98% of theMaximum Density?

4. What is the LBR?

Using the following graph, answer these questions:

Exercise


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15

20

30

4050

100

150

200

L.B

.R. A

T 0.

1” P

ENET

RAT

ION

WATER CONTENT, %

DRY

UN

IT W

T. (P

.C.F

.)

6% 7% 8% 9% 10%125

126

127

128

129

130

Exercise


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What is the method number for the Standard Proctor?

What is the method number for the Modified Proctor?

Learning Outcomes


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The standard penetration resistance for the LBR has been standardized to _____.

The LBR value is NOT affected by moisture at the time of compaction.

True or False

Learning Outcomes


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Design Std. 505 -Sheet 1Flexible Pavement

Embankment Utilization


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Design Std. 505 –Sheets 2 & 3Rigid Pavement with Treated Permeable Base (2)

Rigid Pavement with Asphalt Base (3)



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Design Std. 505 –Sheet 4Rigid Pavement with Special Select Option



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Design Std. 505 (Combination of Sheets 1 - 4)

Soil Classification

Symbol Soil Classification AASHTO M-145

S Select A-1, A-3, A-2-4**

S+ Special A-3*** with Min. Average Lab PermeabilitySelect of 5x10-5 cm/sec as per FM 1-T215

P Plastic A-2-5, A-2-6, A-2-7, A-4, A-5, A-6, A-7 (All with LL<50)

H High Plastic A-2-5, A-2-7, A-5 or A-7 (All with LL>50)

M Muck A-8

** Certain types of A-2-4 materials are likely to retain excess moisture and may be difficult to dry and compact. They should be used in the embankment above the water level existing at the time of construction. They may be used in the subgrade portion of the roadbed when approved by the District Geotechnical Engineer.

***When allowed by the plans, some types of A-2-4 material may be approved in writing by the District Materials Engineer. This material must meet the minimum lab permeability requirements, be non-plastic, and not exceed 12% passing the No. 200 sieve.


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Soil Classification


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Soil Classification


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From the information on the two preceding pages answer the following questions:

Slide 29, could this material be used as roadway embankment? If so where?

Slide 30, could this material be used as roadway embankment? If so, where?

Determine where A-3 material could be used.

Determine where A-2-4 material could be used.

Learning Outcomes


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CLAYEY SOILS... SHEEP FOOT ROLLER

CLAYEY SOILS “BLEEDING”.... TURN OFF VIBRATOR, STATIC & TRAFFIC ROLLERS

SANDY SOILS.... WATER & VIBRATE

HIGH DENSITY MATERIAL & BRIDGING.... LIGHT WEIGHT, NO VIBRATION HIGH SPEED INITIALLY

Compaction Suggestions & Techniques

Bleeding – When moisture is drawn up by capillary action to the surface of the material being compacted.

Bridging – When the compactive effort does not penetrate the full thickness of the lift being compacted.

Walking out – When applied to “Sheepsfoot” rollers refers to attaining less than 1” (25 mm) penetration into the soil.


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Any Questions


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Documents

lesson 2 - CTQP Home Page Level 2/Student lesson...Student Manual Lesson – 2 Density Theory Version 1.0‐ 1/15 2‐14 2-13 MODIFIED PROCTOR STANDARD PROCTOR Method typically used