Innovative Uses for RAP in Road Construction and Repair

Amanda Hufft

Outline

• RAP Availability• FDOT’s Research

RAP in Florida: A Call for Innovation

Introduction to ReCharge™

• 100% RAP Surface Paving• 100% RAP Base Construction• Pothole Patching

Construction of Cold Mixtures

Outline

RAP Availability

February 25, 20213

→ Reported tonnage of stockpiled RAP represents roughly 1½ years of inventory nationwide

→ About 94% producers reported having stockpiled RAP

NAPA’s Asphalt Pavement Industry Survey on Recycled Materials & WMA Usage (2019)

What can you do with a surplus of RAP??>>

High RAP Asphalt Mixes forLow Volume Roads

BACKGROUND

→ 1.8 million tons of RAP produced each year from FDOT yearly maintenance and rehabilitation

→ Agency representatives expressed interest in economical solutions for:→ Paving unpaved roads→ Resurfacing existing low volume roads

February 25, 20214

BE 194 (FDOT and TTI, Nov. 2018)

High RAP Asphalt Mixes forLow Volume Roads

February 25, 20215

BE 194 (FDOT and TTI, Nov. 2018)

21,780

84,320 106,100

14,728

1,563 16,291

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Rural36,508 mi

Urban85,883 mi

Total122,391 mi

Mile

s

Paved and Unpaved Proportions forRural and Urban Roadways in Florida

(Table HM-51, FHWA 2014)

UnpavedRoadsPavedRoads

Length by Functional System with Less than 1,000 ADT in Florida

(Table HM-57, FHWA 2014)

Functional System Rural Urban Total % ADT

< 1,000 (mi) (mi) (mi) Principal Arterials 20 --- 20 0.3 Minor Arterial 105 14 119 1.9 Major Collector 1,210 232 1,442 13.8 Minor Collector --- 118 118 2.3 Total (mi) 1,336 363 1,699 % of Total Length 3.7 0.4 1.4

COMMON DRAWBACKS OF UNPAVED ROADS→ Require frequent maintenance

→ Higher risk of rutting and washboarding

→ Requires routine dust control treatments

Cold Recycled Mixtures

February 25, 20216

→ Cost comparison indicated savings of 20-50% with cold recycling

→ LCCA concluded the most favorable option was 100% RAP foamed cold recycled mixture

→ Cold recycled mixtures generally did not meet strength requirements and experience accelerated rutting at early load cycles

Conserve Resources

Low Cost(40-50% less than other methods)

Ease of Use(commonly used with emulsified or foamed asphalt)

BE 194 CONCLUSIONS

ReCharge™ — An advanced cold mix additiveReCharge™ allows for easy blending, spreading, and compaction of 100% RAP material by activating the aged binder on the surface of RAP withoutheat and no additional asphalt.

→ Allows for resurfacing dirt roads at minimal cost

→ Ideal for cold-mix/pothole and patch repairs

→ Job site mixing or off-site pre-mixing

→ No special equipment required

→ Remains workable for several hours

→ Allows traffic within hours of construction

February 25, 20217

KEY BENEFITS

ReCharge™ — Laboratory Study

SPECIMEN PREPARATION

→ Dose RAP with ReCharge™ and compact to 150 gyrations

→ Place specimen in front of fan for 30 minutes

→ Cure in 60°C oven for 48 or 72 hours

February 25, 20218

Laboratory Study on Curing

2378

2800

Min. 1,250lbtested @ 40°C

0 1 2 3 4

0

500

1000

1500

2000

2500

3000

48 72

Mar

shal

l Sta

bilit

y (lb

)

Curing Time @ 60°C (hr)

Marshall Stability vs. Curing Time @ 60°C

100% RAP Cold Mix — Surface PavingPROJECT OVERVIEW

February 25, 20219

Location: Gulf Point Rd, Santa Rosa Beach, FL

Traffic: residential road with mostly car traffic

Objective: pave a 100% RAP road using existing RAP stockpileon top of an existing RAP aggregate base

Construction Dates: 07/31/19 to 08/02/19

100% RAP Cold Mix — Surface Paving

February 25, 202110

Additive Dosing

Mixture Blending Final Product

MIXPRODUCTIONSanta Rosa Beach, FL

100% RAP Cold Mix — Surface Paving

February 25, 202111

CONSTRUCTIONSanta Rosa Beach, FL

100% RAP Cold Mix — Surface PavingINITIAL PERFORMANCE

→ Cars were able to drive on roadway within minutes of compaction

→ No visible signs of rutting

→ Hardness comparable to HMA after placement

→ No significant tenderness→ Edge compaction is crucial to performance

February 25, 202112

Santa Rosa Beach, FL – 08/02/19

100% RAP Cold Mix — Surface PavingFIELD SURVEY – 02/12/20

→ Ride quality: light vibrations with no speed reduction necessary

→ No rutting or cracking

→ Some weathering and raveling mostly along edges

February 25, 202113

Santa Rosa Beach, FL – 02/14/21

100% RAP Cold Mix — Base ConstructionPROJECT OVERVIEW

February 25, 202114

Location: Riverview Park Rd, Hannibal, MO

Traffic: park road leading to a water treatment plant, low traffic

Objective: mill existing over-crowned asphalt pavement and usemilled RAP to create a stable base for an asphalt overlay

Construction Dates: 09/29/20 and 10/01/20

100% RAP Cold Mix — Base Construction

February 25, 202115

MIX PRODUCTIONHannibal, MO

100% RAP Cold Mix — Base Construction

February 25, 202116

BASE CONSTRUCTIONHannibal, MO

Spreading Mix

Compaction

Finished Product

100% RAP Cold Mix — Base Construction

February 25, 202117

OVERLAY PAVINGHannibal, MO

100% RAP Cold Mix — Pothole PatchingPROJECT OVERVIEW

February 25, 202118

Location: City of Ridgeland, MS

Traffic: all city roads with varying traffic

Objective: use existing RAP stockpile to patch potholes on cityowned roads

Construction Dates: Ongoing since early 2020

100% RAP Cold Mix — Pothole PatchingMIX PRODUCTIONCity of Ridgeland, MS

February 25, 202119

100% RAP Cold Mix — Pothole Patching

February 25, 202120

POTHOLE PATCHINGCity of Ridgeland, MS

References

February 25, 202121

→ Arambula-Mercado, E., Chavarro-Munoz, S.J., Hu, S., Epps, J., Sug Park, E., and Epps Martin, A. (2018). High Reclaimed Asphalt Pavement (RAP) Asphalt Mixes for Low Volume Roads. Florida Department of Transportation, Tallahassee, FL.

→ Cox, B.C. and Howard, I.L. (2015). Cold In-Place Recycling Characterization Framework and Design Guidance for Single or Multiple Component Binder Systems. Report No. FHWA/MS-DOT-RD-15-250 Vol. 2, Mississippi Department of Transportation, Jackson, MS.

→ Williams, B.A., Willis, J.R., and Shacat, J. (2020). Asphalt Pavement Industry Survey on Recycled Materials and Warm-mix Asphalt Usage: 2019. Information Series 138 (9th

edition). Federal Highway Administration, Washington, DC.

Questions?