RUT MIX CHALLENGE
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Transcript of RUT MIX CHALLENGE
RUT MIX CHALLENGE
GAUTRANSRPF NOVEMBER 2006
RUT MIX CHALLENGE
• The need arose from increased occurrence of premature failures
• As a result Client bodies want to move away from asphalt to concrete
• Better solution would be a properly designed asphalt that will be:– Rut resistant– Durable at low and high temperatures– “User Friendly” (Manufacturing & Placing)
RUT MIX CHALLENGE
• Role players in asphalt industry to develop 2 asphalt mix designs namely:– Rut resistant intersection mix– Every day highway mix
• Subsequently high modules asphalt included– Shell with low pen binder (French Technology)– Sasobit with 40/50 or Sasoflex (German & French Technology)
These mixes will then be paved on a freeway in Pretoria and tested for rutting, fatigue etc.
• Rules for mix design:– No modified binders (Rut mix & Highway mix)– Any grading (Not limited to Colto Spec.)– Mixes to be verified prior to paving of trials in Pretoria– Reference mix to be paved and tested prior to trials being paved
RUT MIX CHALLENGE
RUT MIX CHALLENGE
WEST RAND
Mix design process
– First plant trials completed– Intersection mix is promising (Performance testing indicates
good rut resistance)• Paving trial planned on R25
– Freeway mix needs refining• Further plant trials planned
RUT MIX CHALLENGE
RUT MIX CHALLENGE
EAST RAND
Performance requirements
Test type utilized
Criteria set Performance Value
Mix 1 Mix 2
Mix 1: WC for highly trafficked roads
Mix 2: WC for highly trafficked intersection
Quartzite Dolerite Quartzite Dolerite
Deformation resistance
MMLS on briquettes at 50°C wet [on cores] (mm)
<1.8 <1.6 1.74 1.4 1.2
Average deformation per cycle in 2 000 – 3 000 range of DCT ()
<0.4 <0.35 0.12 0.33
Gyratory voids at 300 repetition (on a 5% Marshall VIM’s setting)
>2.7 >3.0 2.8 3.2 4.3
Durability Mod Lottman >80% >80% 85 90 84
Fatigue
4 Pt beam fatigue (at 200 micron strain) : Reps to failure
>2 million >2 million To be tested 3.179 m
ITS (kPa) >1 000 >1 000 1368 1222
RUT MIX CHALLENGE
• Verification with Performance Properties
RUT MIX CHALLENGE
AKASIA ROAD SURFACING
Akasia Road Surfacing - Mix design process
– Design in process– Change of aggregate source (From Rooiberg to Granite from
Buffalo quarry Naboomspruit)– Mix type not finalized
RUT MIX CHALLENGE
RUT MIX CHALLENGE
BLACK TOP
NICO WILCOCKS
Mix design process
– TRH8 Coarse– Chrome Slag from Witbank
• High PSV
• Rough surface texture
• Good adhesion
• Varying surface area
• No swell problems
– Mix used successfully on N4 at Tollgate bypass
RUT MIX CHALLENGE
NICO WILCOCKS
RUT MIX CHALLENGE
HIGH MODULUS ASPHALT
(HiMA)
High Modulus Asphalt (HiMA)Mix design process
Sasobit– Soillab busy with mix designs similar to Hamburg International
Airport (40/50 Bitumen + 3% Sasobit)
Shell– Aggregate and bitumen samples sent to Shell Global Solutions
France (Low pen bitumen)
RUT MIX CHALLENGE
ACHIEVING VOLUMETRICS IN ASPHALT
BAILEY METH0D
IS NOT A SPECIFICATION!!!
• What is voids and VMA?
Bailey Method
Volume Voids (3% - 6%)
Volume Binder (10% - 17%)
Volume Aggregate (83% – 90%)
VMA