Updating Bituminous Stabilized Materials Guidelines Mix Design Report Phase II

- No sign of significant initial densification occurred on BSMs. However, cohesion loss or
stiffness reduction of the trafficked materials increases as number of load application
increases.
- The level of disintegration and ravelling on BSMs under wet trafficking, shows that
cohesion loss and stiffness reduction develop progressively. The failure mechanism of
BSMs is that severe reduction of cohesion or stiffness occurs, before exponential loss of
materials occurred.
- Sample preparation need care to ensure smoothness of the test surface. Briquettes that
spalled during cutting show an early disintegration on wet trafficking.
- The performance of BMSs exposed to moisture during trafficking shows significant
differences. The long cured BSM-emulsion proves to be moisture resistant, than BSMs
with laboratory accelerated curing.
- The influence of the addition of the active filler in BSMs is vital for the improvement in
moisture susceptibility. The results indicate that BSMs with addition of 1% cement is
more moisture resistant compared to BSMs with addition of Lime or no active filler.
However interesting results on the addition of 1% lime is that, the BSMs endure moisture
resistant to a certain saturation level up to 80%, thereafter exponential disintegration
occurred.
4.3 Testing Temperature
- The MMLS3 wet trafficking and ITS tests were conducted at controlled 25 o C. It is obvious
that the field temperature on BSMs varies significantly, however in South Africa moisture
related damage occurred during rainfall period. During that period air temperature, do
not exceed 30 o C. Therefore, BSM-layer being a base or subbase its temperature will not
excess 25 0 C.
4.4 ITS test results
- The comparison of the ITS Values in all BSMs show no significant difference, with
exception of BSM-emulsion made of quartzites and no active filler. This indicates that ITS
test is not particular sensitive to moisture effect.
- From the analysis, long term cured BSM-Mixes proved to be highly moisture resistant
compared to laboratory accelerated cured BSM-mixes. However the ITS results show
insignificant difference between these BSMs. The lack of reliability and repeatability of
the ITS test for use in ranking BSMs in terms of moisture susceptibility, should preclude
its use for important applications of BSMs.
- Ravelling-depth of 4mm under the MMLS3 wet trafficking appears to be critical. It is
appropriate to extend testing beyond 4mm for better screening the BSMs.
33