Mixture Design Process

Dale A. Rand, PE

Full Depth Reclamation with

Asphalt Binders Workshop

1

.

1. Why Do We Need A Mix Design

2. Field Sampling

3. Materials Preparation in the Lab

4. Moisture Density Curve & PI

5. Laboratory Mixing

6. Sample Curing and Molding

7. Curing Molded specimens

8. Laboratory Tests

9. Data Analysis

OUTLINE

2

.

• Evaluate compatibility of materials

o PI results can dictate if stabilization is an option

• Base Gradation: Very fine existing base may require adding rock to

modify gradation

• Optimize the mixture for Performance

Strength & Resistance to Resistance to Moisture Damage

• Optimize the mixture for economy

WHY DO WE NEED MIX DESIGN?

3

.

FIELD SAMPLING

4

.

• Process Material

oMaintain RAP, salvage and new

base separate

• Measure PI

• M-D Relationship

Proctor Tex-113-E

• Laboratory Mixing

• Fabricate specimens and

determine IDT

• Fabricate specimens and

determine UCS

• Select potential stabilizer(s) &

application rate(s), if needed

OFTEN TIMES 4 TO 8 DIFFERENT

MIXTURES UNDER CONSIDERATION

MIXTURE DESIGN – GENERAL SEQUENCE

5

.

Generally,

• Higher RAP percentages yield better mix results

• Materials with PI approaching 10 may require lime pretreatment

o PI does not solely dictate compatibility

Some materials with PI > 10 have been successfully treated

Some materials with PI < 5 have failed mix design criteria with both emulsion and foam

PI>20 generally won’t produce acceptable materials

• Additive content should be limited to ~ 1%

• Emulsion may be more successful with “marginal” materials

• The method of applying the oil will have some impact on costs

and construction process control

MIX DESIGN APPLICATION NOTES FOR EMULSION AND FOAM

6

.

LAB SAMPLE PREP

7

FDR: Lab # 131155

Weigh Up sheet

LAB # 130506

Existing Add

Seive Base RAP RAP

1 3/4 4.0

1 1/4 7.0

7/8 14.0

5/8 20.0

3/8 7.0

# 4 12.0

#40 14.0

"- # 40 22.0 100.0

75.0% 25.0% 0.0%

1 3/4 3.0 0.0 0.0

1.25 5.3 0.0 0.0

7/8 10.5 0.0 0.0

5/8 15.0 0.0 0.0

3/8 5.3 0.0 0.0

# 4 9.0 0.0 0.0

#40 10.5

"- # 40 16.5 25.0 0.0

SUM 75.0 25.0 0.0

Weights In Gram: Total Wt 4000

Reclaimed Existing ADD

Base RAP Base

130506 0 0

1 3/4 120.0 0.0 0.0

1.25 210.0 0.0 0.0

7/8 420.0 0.0 0.0

5/8 600.0 0.0 0.0

3/8 210.0 0.0 0.0

# 4 360.0 0.0 0.0

#40 420.0

- # 40 660.0 1000.0 0.0

Total 3000.0 1000.0 0.0

4000

25.0%75.0% 0.0%

FDR: Lab # 131155 Weigh Up Sheet

LAB SAMPLE PREP

8

9

Size Passing RetainedRequired

3" 100.0 0.0

2" 100.0 0.0

1 3/4 100.0 0.0

7/8 92.7 7.3 10-35

3/4 92.7 7.3

3/8 76.2 23.8 30-50

No. 4 61.7 38.3 45-65

# 10 61.7 38.3

# 40 29.0 71.0 70-85

# 200 29.0 71.0

LL PL

41 28

Unified: S

AASHTO A-2-7

FAA NO

2.75 4

7.3 7.8 9.8 12.2

121.3 122.7 126.7 122.7

2,027.8

126.59 Std Error

10.00 0.20705 9.4

TEX-101E

TEX-106E

Liquid Limit

Sieve Analysis (%)

Plastic Limit

Plasticity Index

TEX-113E

Estimated

Moisture

ASTM D2487Standard Classification

Compaction M/D Relationship

Soil Sampling

Estimated Specific Gravity Points on Graph:

Atterberg Limits

13

Soil Preparation

Max Density (kg/m3)

PI

0

Soil Classification

Group Index

Test Method Used:

TEX-100E

TEX-104E

TEX-110E

TEX-105E

Sieve Analysis

Moisture Content in %

Optimum Moisture(%)

Dry Density (pcf)

Maximum Density (pcf)

121.3

122.7

126.7

122.7

119.3

121.3

123.3

125.3

127.3

129.3

5.1 7.1 9.1 11.1 13.1

Dry

Den

sit

y (

pcf)

Moisture Content (%)

Moisture - Density Relationship

PI< 5

Potential Issues with Strength

5<PI<10

Ideal

10<PI<20

Maybe Used

(Depending on Mixing Ability)

PI>20

Not Suitable

MOISTURE DENSITY & PI

10

11

.

• Add moisture to the RAP and Base mixture and allow it to

cure for 24 Hrs

Only add 70% of required moisture to RAP/Base mixture

when using emulsion

• After mixing asphalt with sample cure for 30 minutes at

140F in a sealed container prior to molding

CURING MIX PRIOR TO MIXING AND COMPACTION

12

LABORATORY MIXERS: NEED A HIGH SHEAR MIXER

13

LABORATORY MIXERS: FOAMING UNIT

14

MOLDING TEST SPECIMENS

15

SOIL COMPACTOR – 6”x8” MOLDS SUPERPAVE GYRATORY COMPACTOR

6” x 3.5 MOLDS

MOLDS FOR UNCONFINED

COMPRESIVE STRENGTHMOLDS FOR INDIRECT TENSILE STRENGTH

MOLDING & CURING TEST SPECIMENS

16

• IDT SAMPLES CURED FOR 72 HRS. @ 104F AFTER MOLDING

• UCS SAMPLES CURED FOR 48 HRS. @ 140F AFTER MOLDING

IDT SAMPLES CURED FOR 72 HRS. @ 104F AFTER MOLDING

Laboratory Tests

18

INDIRECT TENSILE STRENGTH

1. Unconditioned

2. Moisture Conditioned

Moisture Conditioning

• 24 Hr. Soak

Laboratory Tests

19

UNCONFINED COMPRESIVE STRENGTH

1. Unconditioned

2. Moisture Conditioned

Moisture Conditioning

• 24 Hr. Soak

80.5 85.876.0 83.5

Retained Unconfined

Compressive Strength (psi)

@ 25 °C [Tex-117-E]

191 163 147

237 214 171 302 237

155 198

119.6

49.8 79.9 63.1

3.5

5.3 5.3 8.3

Percent Emulsion

% H2O (added)

4.5 5.54.5 +

1.0% Lime

4.5 +

1.0% Cement

Density, lbs/ft^3 120.2 122.8

64.1 56.3

5.3 5.3

123.9 124.1

Tensile Strength (psi)

@ 25 °C (72 hr. Cure)

[Tex-226-F]

51.5

Mixture Data and Volumetrics

Dry Unconfined

Compressive Strength (psi)

@ 25 °C

% Retained Unconfined

Compressive Strength

[Tex-117-E]

DATA ANALYSIS

20

Roadway thickness to be reclaimed is 6", consisting of 2.0" of ACP, 2.0" of Base and 2.0" of Stockpile

Emulsion Content Percentage: 4.0%

Required Additive: 1% cement

Required Moisture Before Emulsion Addition: 6.2%

1 3/4" 98.1

1 1/4" 96.7

7/8" 89.7

3/8" 58.1

No. 4 38.6

No. 10 28.7

No. 40 20.2

No. 200 15.1

Sand Equivalency

Tex-203-F

Max. Dry Density

Tex-113-E, PCF

PI

Tex-106-E10

Sieve Size % Passing

Retained Unconfined Compressive

Strength (psi) @ 25 °C [Tex-117-E]

19

117.3

Property

Tensile Strength (psi) @ 25 °C (72

hr. Cure) [Tex-226-F]

Dry Unconfined Compressive

Strength (psi) @ 25 °C [Tex-117-E]

80% min98.0

152

% Retained Unconfined

Compressive Strength [Tex-117-E]

72

Criteria

50 min

155 150 min

For

Information

Only

Sieve Analysis of Aggregate Blend

RAP material added to the existing roadway.

Performance Criteria

MOISTURE DENSITY & PI

21