RUT MIX CHALLENGE GAUTRANS RPF 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

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

EAST RAND

Performance requirements Test type utilized Criteria setPerformance Value Mix 1Mix 2 Mix 1: WC for highly trafficked roads Mix 2: WC for highly trafficked intersection QuartziteDoleriteQuartziteDolerite Deformation resistance  MMLS on briquettes at 50°C wet [on cores] (mm) <1.8<  Average deformation per cycle in – range of DCT (  ) <0.4<  Gyratory voids at 300 repetition (on a 5% Marshall VIM’s setting) >2.7> Durability  Mod Lottman >80% Fatigue  4 Pt beam fatigue (at 200 micron strain) : Reps to failure >2 million To be tested3.179 m  ITS (kPa) > 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

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