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WARM MIX ASPHALTFlexural Stiffness & Fatigue Performance Kim Jenkins Alex Mbaraga, Johann van den Heever, Stephan van der WaltSANRAL CHAIR in Pavement Engineering Stellenbosch University5th September 2011

1ACKNOWLEDGEMENT

National Asphalt

South African Roads FederationSARF

WMA in KwaZulu NatalIntroductionWMA TechnologiesMix CompositionsRecycled Asphalt ContentLaboratory ProcedureLaboratory Results CompactionLaboratory Results Flexural Stiffness Laboratory Results FatigueLaboratory Results Visco-elastic IndicationConclusions and Recommendations

OUTLINE

5Trends Europe (& South Africa?)Growing health, safety and environmental awareness of the general public and industry (yes, to lesser degree)Significant efforts to save non-renewable fossil fuels and aggregates, conserve energy and reduce emissions and exposures (yes, to much lesser degree)Advances in technology, coupled with growing environmental concerns, have led to research into more environmentally friendly production processes (yes)Acknowledge: Martin van de Ven (TU Delft)6Europe versus SAEuropean Community strategy: sustainable construction techniquesEFCT: Environmentally Friendly Construction Technologies (WMA Interest Group in SA)But. In realistic competition: the benefits of the lower operating temperatures resulting in asphalt mixture quality and durability on the road must compete with the properties that can be obtained with Hot mix (WMAIG is trying to answer this question)7Road Agencies (EU vs SA)Most agencies are withdrawing from direct technical involvement (not entirely in SA)New contracts are making there impact (not yet)Agencies are strongly influenced by politicians (safety, noise reduction, health, individual rights, etc: what scores for a government to get elected again) (not quite the same in SA)Financial budget is (always) under pressure (same)

8Consequence of political decisions in EuropeLCA approach: search for Environmentally friendly materials satisfying LCA requirementsProducing asphalt mixtures at lower temperatures. Recycling at highest possible level: RAP can be a very important material in the decision between cold and hot/warm recycling (black gold) Perpetual pavements: (functional) performance forever. Durability is very important in LCA

INTRODUCTIONEvaluate Flexural Stiffness and Fatigue PerformanceFlexural Stiffness - Mix PropertyFatigue - Performance CriteriaTest - Pneumatic 4-Point Beam Apparatus

INTRODUCTION ContdWMA mix recipes plant produced Surface and Base MixesEquivalent HMA Mix as Control Mixes 2 Main WMA Technologies - Additive (Chemical and Organic ) and Foaming Process Technologies

10WMA TECHNOLOGIESAdditive Technology - RedisetTM WMX (Chemical Additive) and Sasobit (Organic Additive)Foaming Process NA Foam Tech

Binder Grades60/70 and 80/100ModifiersA-P1 (EVA) and A-E2(SBS)Mix Type 1:- EVA + RedisetTM WMX and EVA + NA Foam TechMix Type 2:- SBS and Sasobit -SasoflexMix Type 3:- Additive (Rediset or Sasobit) or foaming Technology but no EVA or SBS

MIX COMPOSITIONS

RECYCLED ASPHALT CONTENTSurface Mixes 10% RA20% RABase Mixes 10% RA 40% RA

Table 1 Summary of Mix TypesHMA Surface Mix Control Mixes (Type D Mix)WMA Surface Mix Plant & Field Trials (Type D Mix)WMATechnology10% RA 60/70 (Control 1)10% RA 60/70 RedisetTM WMXChemical Additive20% RA 80/100 A-P1 (EVA) (Control 2)20% RA 80/100 A-P1 (EVA and RedisetTM WMX)10% RA 60/70 (Control 1)10% RA 60/70 Foam TechFoaming Process10% RA 60/70 (Control 1)10% RA 60/70 SasobitOrganic Additive20% RA 80/100 A-E2 (SBS) (Control 3)20% RA 80/100 A-E2 (SBS and Sasobit) SasoflexHMA Base Mix Control Mix (Type B)WMA Base Mix Plant and Field Trials (Type B)WMTechnology10% RA 60/70 A-P1 (EVA) (Control 4)10% RA 60/70 A-P1 (EVA and RedisetTM WMX)Chemical Additive10% RA 60/70 A-P1 (EVA and Foam Tech)Foaming Process40% RA 80/100 A-P1 (EVA) (Control 5)40% RA 80/100 A-P1 (EVA and RedisetTM WMX)Chemical Additive10% RA 60/70 A-E2 (SBS) (Control 6)10% RA 60/70 A-E2 (SBS and Sasobit) Sasoflex Organic Additive 40% RA 80/100 A-E2 (SBS) (Control 7)40% RA 80/100 A-E2 (SBS and Sasobit) Sasoflex

Testing is still commencing for some of the mixes 14LABORATORY SPECIMENSManufacture of SpecimensCompaction Modified method (KZN)Sawing of Slabs Beams (SU)EvaluationBRD test

SUCM = ?15LABORATORY Compaction

Modified Compaction Method

LABORATORY Compaction2

ABCD

Table 2 Compact-ability of Mixes vs. Field Compaction LABORATORY RESULTS Compaction Modified SUCM @ 35 PassesType D: 20% RA 80/100 A-E2 (Sasobit and SBS) SasoflexA-E2 SasoflexThickness (mm)Rice Density(kg/m3)Core Bulk Density (kg/m3)Percentage of Rice (%)Slab 1732464237896.51 Slab 2772464237096.19Slab 3722464237696.43Average Compaction (%) (Void Content %)96.93 (3.1%)Field CompactionA-E2 SasoflexThickness (mm)Rice Density(kg/m3)Core Bulk Density (kg/m3)Compaction of Rice (%)Core 1542464233094.56Core 2742464235995.74Core 3602464235195.41Core 4752464236595.98Core 5702464236295.86Core 6602464235595.58Average Compaction (%) (Void Content)95.52 (4.5%)

Comparison between lab and field voids18LABORATORY RESULTS Compaction (2)Table 3 Compact-ability of SpecimensBeam NoMass in Air (g)Mass in water (g)Rice Density (kg/m3)BRD (kg/m3)Void Content (%)Type D: 10% RA 60/70 AP-1(EVA + RedisetTM WMX) (SLAB 2) at 35 Passes130121754247623923.4231401838247624102.7330041762247624162.4429901751247624132.5Type D: 10% RA 60/70 AE-2 (SBS + Sasobit) Sasoflex ( Slab 1) at 35 Passes130231749247123714.0230131751247123853.5330451766247123783.8430741779247123734.0Type D: 20% RA 80/100 AE-2 (SBS and Sasobit) Sasoflex (Slab 1) at 35 Passes130631765247023534.7231471832247023883.3330571783247023943.1430071739247023664.2Type B: 10% RA 60/70 AE-2 (SBS and Sasobit) Sasoflex (Slab 2) at 35 Passes131461827248923734.7230791800248924053.4330301767248923943.8429491719248923933.9Type B: 40% RA 80/100 AP-1 (EVA and RedisetTM WMX) (Slab 3) at 35 Passes129591713250023555.8230491776250023784.9330501770250023774.9431241816250023784.9

Void content Ranges from 2.4% to 5.8% for 35 Passes Temperatures at time of compaction??

191. Flexural Stiffness TestSinusoidal Constant Strain for 300 cyclesStrain regime - 300Temperature Sweeps - 50C to 25 0C (Interval of 50C )Frequencies 0.5Hz, 1Hz, 2Hz,5Hz & 10HzThus, Isotherms Development of Master Curve at Reference Temperature 20 0C

LABORATORY TESTING

300 microstrain yielded N = 2million for fatigue, so it was selected for Master Curves20LABORATORY Flexural StiffnessDevelopment of the Flexural Stiffness Master Curve

Reference Temperature of 20 C. Arhennius equiation includes R (Univ Gas Constant) and Ra (Activation Energy)212. Fatigue TestSinusoidal Constant Strain for a maximum of 3.5million cyclesFrequency 10HzTest Temperature - 50C 3 Selected Strain regimes from Low, High and 300Test begun at a strain of 300Development of the Log Nf vs. Log

LABORATORY TESTING

Low is 180 to 220 microstrain. High is >380 microstrain. The 300 microstrain falls between low and medium22Graph 1 Type D 10% RA 60/70 Surfacing MixesLABORATORY RESULTS Flexural Stiffness

A Combination of plant and final trial mixes 2. Control compared similar for both cases 3. Plant versus field trials, sometimes better, sometimes worse 4. Some testing incomplete23LABORATORY RESULTS Flexural StiffnessGraph 2 Type D 20% RA 80/100 Surfacing Mixes

Plant and field trial mixes. Control mixes always lower than both WMA plant and field trials. Plant mixes always higher than field trials (Elastomer and Plastomer)24LABORATORY RESULTS Flexural StiffnessGraph 3 Type B 10% RA 60/70 Base Mixes

SBS WMA better than HMA. 2. EVA HMA better than WMA. 3. EVA + Foam similar to EVA + Rediset 25LABORATORY RESULTS Flexural StiffnessGraph 4 Type B 40% RA 80/100 Base Mixes1. SBS HMA slightly better than WMA, but comparable. 2. EVA HMA better than WMA26LABORATORY RESULTS Flexural StiffnessGraph 5 Type D Surfacing Mixes Additive Technology

Sasobit WMA > Rediset WMA for 10% RA and 60/70SBS+Sasobit WMA = EVA + Rediset WMA for 20% and 80/10027LABORATORY RESULTS Flexural StiffnessGraph 6 Type B Base Mixes Technologies and Modifiers

NB: SLOPE!!SBS + Sasobit > EVA (Rediset or Foamtech) BUT check lower frequencies NB INTERPRETATIONNotice the EVA and Foam Tech as well as EVA and Rediset 28LABORATORY RESULTS FatigueGraph 7 Type D 10% RA 60/70 Surfacing Mixes

HMA > Sasobit, Rediset and Foamtech for Plant and Final trials29LABORATORY RESULTS FatigueGraph 8 Type D 20% RA 80/100 Surfacing Mixes

HMA > WMA Sasoflex (plant) > Saoflex (final). WMA EVA+Rediset (plant) > (final) > HMA30Graph 9 Type B 10% & 40% RA 60/70 Base MixesLABORATORY RESULTS Fatigue

All SBS: HMA (10% ) > HMA (40% RA) > WMA (10% and 40% RA)31Graph 10 Type B 40% RA 80/100 Base MixesLABORATORY RESULTS Fatigue

No control for Type B 40% RA 80/100 A-P1 (EVA) Testing underway. HMA (SBS) > WMA (EVA) > WMA (SBS)32LABORATORY RESULTS Visco-elasticGraph 11 Type D 10% RA 60/70 Surfacing Mixes (Freq. 10Hz)

How elastic are WMA mixes compared to the HMA mixes Visco-elastic indication amongst the Technologies 33LABORATORY RESULTS Visco-elasticGraph 12 Type D 20% RA 80/100 Surfacing Mixes (Freq. 10Hz)

Incorporation of the modifier more elastic than unmodified mixes even with lower RA content 34Surfacing (no SBS or EVA) with 10% RA 60/70 for plant versus final trial mixes no consistent trend, sometimes higher, sometimes lower(Control) HMA = WMASasobit > Rediset for WMASurfacing (SBS or EVA) with 20% RA 80/100 Plant > final field trial mixes for both SBS and EVASasoflex WMA = EVA + RedisetBases with 10% RA 60/70 SBS WMA > HMAEVA HMA > WMAEVA + Foam similar to EVA + Rediset Bases with 40% RA 80/100 + EXP1655 SBS HMA slightly > WMA (Sasobit)EVA HMA > WMA (+ Rediset) CONCLUSIONS Flexural stiffness

CONCLUSIONS Additives and ElasticityElastomer and Plastomer, Flexural StiffnessFor SBS the WMA generally >or= Control (HMA)For EVA the WMA generally < Control (HMA)Visco-elastic Behaviour Surfacing 10% RA 60/70Elastic HMA WMA ViscousElastic - Sasobit Foamtech Rediset - ViscousBehaviour Surfacing 20% RA 80/100 + SBS or EVA EVA = SBS with variability

Surfacing 10% RA 60/70HMA > WMA (plant& final)For WMA overall Foamtech > Sasobit > RedisetSurfacing 20% RA 80/100HMA > WMA Sasoflex (plant) > Sasoflex (final)WMA EVA+Rediset (plant) > (final) > HMABase 60/70 + SBS (all)HMA (10% ) > HMA (40% RA) > WMA (10% and 40% RA)Base 40% RA 80/100 + SBS or EVAHMA (SBS) > WMA (EVA) > WMA (SBS)

CONCLUSIONS Fatigue

Laboratory and full scale trial??Further analysis - WMA technology vs. Rheologyi.e. lubrication vs. technology, cohesive and adhesive Local materials and WMA technologies RECOMMENDATIONS