Richard S. Williammee, Jr., MSCE, P.E.

TxDOT Fort Worth District

2011 Transportation Short Course                                                                October 12, 2011

RASRAP RASRAP

~ 10 million tons of  10 million tons of Hot Mix Asphalt produced for TxDOTproduced for TxDOT each year.

832,000+ tons of RAP used in HMAC in 2010.

12 Districts (48%) allowed the use of RAP in hot mix h l i 2006asphalt in 2006.

Districts reluctant to use RAP in hot mix asphalt due to high variability indue to high variability in AC content and gradation.gradation.

Single RAP stockpiles Single RAP stockpiles segregated.

• Approximately 13 million tons of asphalt shingle waste i t dis generated per year– Post manufacture (scrap): 1 5 million(scrap):  1.5 million tons

– Post consumer (tear‐(off): 11.5 million tons

• Less than 5% of shingle waste is recycled

Asphalt 5 0%

Fibers 2.5%5.0%

Asphalt24%Fine Agg.

72.5%Fine Agg.

35 0%Coarse Agg.

60 0% 35.0%60.0%

RASRAP RASRAP

PG 64 22

PG GradeBinder AC %

5 267PG 64-22

RAS

5.2

24.0

67

96

RAP 5.087

PG GradeBinder AC % % in Mix

PG 64-22

RAS

5.2 (4.2)

24.0

67

96

RAP 5.0 (1.0)87 20.0

Combined Grade70.8

PG GradeBinder AC % % in Mix

PG 64-22

RAS5.2 (4.0)

24.0 (1.2)

67

96 5.0RAP 5.0

( )

87

Combined Grade73.7

PG GradeBinder AC % Mix %

PG 64-22

RAS

5.2 (3.25)

24.0 (1.2)

67

96 5.0RAP 5.0 (0.75)

( )

87 15.0

Combined Grade76.6

Be proactive Improve quality Improve quality Reduce costs Comply with FHWA regulations Technolog impro ements Technology improvements Green Agency (reduce the carbon footprint)

TxDOT Administration seeing “doom and gloom” for the overall budget and looking for waysto save money now in all areas.

Material Costs –o Asphalt prices -

Then: PG 64-22 cost $163/liquid ton.Now: PG 64-22 costs $575/liquid ton.

o Aggregate prices – definite price increase $500 million spent annually on HMAC.

10% cost reduction is a significant savings.

RAP, RAS, WMA, Tire rubber, In-Place recycling -new products used to lower current mix costs

Grade dump (softer asphalt grades to addresscracking)g)

Pave-IR to improve consistent temperaturesWMA to lower temperatures and reduceWMA to lower temperatures and reduce

oxidation plus lower fuel costs

Variable and Contaminated RAP

RAS Clumping

Higher graded asphalt for rutting

Early asphalt oxidation Early asphalt oxidation

Early pavement cracking

Lower cost

90

100

70

80

50

60

ent P

assi

ng

30

40Per

ce Maximum Density Line

10

20

0Sieve Size

1 2 3 4 5 6 Avg.

#200 #80 #50 #40 #30 #10 #8 #4 3/8" 1 /2" 5/8" 3/4" 7/8" 1" 1 1/4"

Reclaimed Asphalt Pavement (RAP)p ( )

Fractionating RAP into 2 or more stockpiles can g psignificantly improve variability.

Gradation and composition ofcomposition of fractionated RAP are typically consistent in size and quality.

Uniform & Consistent

-1/2" Inch RAP90

100

70

80Maximum Density Line

50

60

cent

Pas

sing

30

40Per

c

10

20

0Sieve Size

1 2 3 4 5 6 7 8 9 10 1112 13 14 15 16 17 18 19 20 Avg.

#200 #80 #50 #40 #30 #10 #8 #4 3/8" 1 /2" 5/8"

PG GradeBinder AC % Mix %

PG 64-22

RAS

5.2 (3.25)

24.0 (1.2)

67

96 5.0RAP 5.0 (0.75)

( )

87 15.0

Combined Grade76.6

Produced and Placed August 25Photo taken August 26

Ways to mitigate RAP/RAS concerns:y g

increase the target lab density to get more

total asphalt binder into the mixp

start with a lower base asphalt grade to

lessen crackinglessen cracking

utilize a crack measurement test such as the 

Overlay Tester to establish an objectiveOverlay Tester to establish an objective

cracking criteria

use WMA to improve mixing and compaction use WMA to improve mixing and compaction