DIGEST 2006 - Sabita
DIGEST 2006 - Sabita
DIGEST 2006 - Sabita
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PRADO analysis. Large quantities<br />
of this mix have been placed at<br />
the ORTIA with no significant<br />
compaction problems; the<br />
compaction procedures were,<br />
however, thorough, with layer<br />
thickness at 40mm and above.<br />
(c) Verification with performance<br />
related properties (i.e.<br />
original mix specification)<br />
Various performance related<br />
properties were defined to ensure<br />
field performance requirements<br />
would be met. The results of the<br />
fine-tuned mixes to be used in the<br />
Gautrans Challenge are listed in<br />
Table 5.<br />
Field performance to date<br />
The dolerite alternative for the<br />
intersection mix (40/50 pen<br />
binder) was used in three airport<br />
pavement contracts over the past<br />
two to three years. Extracted field<br />
core values confirmed satisfactory<br />
field MMLS values at less than 1.6<br />
mm rutting, and conformance with<br />
all other performance criteria; field<br />
performance to date has been<br />
good, given the extremely<br />
aggressive taxiway traffic (i.e. 22<br />
ton wheel loading; 1 400 kPa tyre<br />
pressure).<br />
This design methodology and<br />
performance criteria were used on<br />
various projects in the Western<br />
Cape (N7 rehabilitation, M5<br />
Rehabilitation, Cape Town<br />
International Airport (CTIA) major<br />
taxiways rehabilitation, and in<br />
Gauteng area (various airport<br />
taxiway rehabilitation and roads<br />
projects). Assessment of these<br />
mixes, on all these pavements,<br />
indicated satisfactory performance<br />
Performance<br />
requirements<br />
Deformation<br />
resistance<br />
Test type and<br />
parameters<br />
used<br />
MMLS on<br />
briquettes at<br />
50 0 C dry (on<br />
cores) (mm)<br />
Average<br />
deformation per<br />
cycle in 2000 -<br />
3000 range of<br />
DCT (µ)<br />
Gyratory voids at<br />
300 repetitions<br />
(on a 5%<br />
Marshall VIMs<br />
volumetric<br />
setting<br />
Criteria set<br />
Mix 1 Mix 2 Mix 1: WC for<br />
highly trafficked<br />
roads<br />
Quartzite<br />
Performance value<br />
Mix 2: WC for<br />
highly trafficked<br />
intersection<br />
Dolerite Quartzite Dolerite<br />
80% 85 90 N/T 84<br />
Fatigue<br />
4 Pt beam<br />
fatigue (at 200<br />
micron strain):<br />
reps to failure<br />
>2 mil >2 mil To be<br />
tested<br />
To be<br />
tested<br />
4.3<br />
N/T 3.2<br />
million<br />
ITS (kPa) >1000 >1000 1 368 >1000 >1000 1222<br />
Table 5: Performance Simulation Properties (Criteria and test values obtained)<br />
109
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