Full Depth Reclamation (FDR) Engineered Mix Design with Asphalt

Emulsion

FDR Mix Design with Asphalt Emulsion

Material evaluation Mix design

Material Evaluation / Preparation

Thickness of cores / slabs Crush bituminous layer to pre-

determined gradation 1.25 inch maximum size SE and washed gradation testing Modified Proctor

analysis – ASTM

D 1557, Method C

Modified Proctor Compaction

y = -18628x2 + 2200.2x + 71.655

R2 = 0.8208

133.5134.0134.5135.0135.5136.0136.5137.0137.5

4.00% 4.50% 5.00% 5.50% 6.00% 6.50% 7.00% 7.50%

Moisture, %

Dry

den

sity

, pcf

OMC=5.9%

Material Evaluation – Modified Proctor

Without emulsion OMC is not for compaction in this case,

but it is used as a material property to set the moisture content required before emulsion addition

Removes somesubjectivity inmoisture content neededbefore emulsion addition

Material Evaluation – Water content before emulsion

If rainfall is ≥ 20 inches: 60 to 75% of OMC if SE < 30 45 to 65% of OMC if SE > 30

If rainfall is < 20 inches: 50 to 75% of OMC if SE < 30 40 to 65% of OMC if SE > 30

This results in a water content close to in-place moisture content on a sealed / overlaid road

Moisture mixed with sample and sealed, typically overnight

Test Performance Parameter

Short-Term Strength Cohesiometer ASTM D1560

Curing

Indirect Tensile Strength (ITS) ASTM D4867

Strength

Retained Strength ASTM D4867

Moisture resistance

Resilient Modulus ASTM D4123

Relative indicator of quality.

Strain or deflection w/ applied load for structural design.

Indirect Tensile Test (IDT) AASHTO TP 9

Thermal Cracking Resistance

Construction & QA/QC Requirements

Reliability

Tests run on 150-mm SGC prepared specimens

FDR and GBS TestsFDR and GBS Tests

Mix Design – Number of specimens

4 emulsion contents Typically 2,700 g weight (dry basis) 8 specimens for STS 16 specimens for ITS and conditioned

ITS 2 specimens for Gmm

3 specimens for IDTCut two from each

Mix Design - Mixing

High energy mixer 10 to 12 inches in diameter Rotates on its axis at 50 to

75 revolutions per minute A mixing paddle which

makescontact with thebottom and side of the bowlrotates on its axis attwice the bowl rotation rateand in the opposite rotationdirection as the bowl

Mix Design - Mixing

High energy mixer60 seconds for

both water and

emulsionTypically non-

heated materials

Mix Design – Pre-compaction curing

After mixing, specimens are cured in plastic cylinder for 30 minutes at 40°C

Simulates aeration the road gets before final compaction – includes shaping with motor grader

Slight moisture loss

Mix Design - Compaction

Superpave gyratory compactor (SGC) 150 mm mold 30 gyrations – simulates field density 600 kPa, 1.25° angle 10 second square pressure

after last gyration Un-heated mold Moisture will not squeeze

out if proper water contentis chosen

Mix Design - Curing

STS specimens:1 hour25°C at 10 to 70%

humidity

ITS / resilient modulus:25°C testing after:

72 hours at 40°C1 day of cooling

Short-term strength (STS) by cohesion

Has been used for a very long time Original intent still applies Practical method for potentially weak

specimen strength testing Compression failure with ITS possible Handling with resilient modulus difficult

Modified for largerspecimens

Specified torqueapplied to nuts forconsistency

STS by Cohesiometer

Cohesiometer measures early strength; tested after 1 hour cure

Load applied

Stress on sample

Shot in cylinder

Great indicator of emulsion curing, in-place early strength, and ability

to carry traffic.

Bulk specific gravity

CoreLok used for density unless it can be shown absorption is low with SSD method

Along with Gmm,

air voids are

determined for

information

Resilient Modulus

Performed before ITS 25°C, 1 Hz Relative quality indicator Can be used for pavement

design

Indirect tensile strength (ITS)

Specimens (dry testing) are conditioned at 25°C for two hours

Conditioned specimens are vacuum saturated a minimum of 55 percent (in most cases) and then soaked 24 hours

Tensile strength calculated Dry and conditioned strength

at each emulsion content

Thermal Cracking Performed at optimum emulsion content Determine crack initiation temperature

Creep and strength testing in IDT Determine required temperature at

depth of top of FDR layer – LTPPBind

FDR Mix Design

SemMaterials, L.P.