Updating Bituminous Stabilized Materials Guidelines Mix Design Report Phase II

4.3 Saturation Level
The moisture ingress (saturation level) in the BSMs depends on in particle interlock, particle
type, binder content, and additions of active filler. The mixes with high void contents shows
higher erosion due to high void pore pressure developed during wet trafficking. Figure 20 and
21 above exhibit that behaviour. Further observations on the results Figure 20 and 21 are that
the BSM-emulsion with Hornfels-RAP plus 1% lime proves to be relative resistant to moisture
damage up to a certain degree of saturation e.g. 80%. Thereafter severe cohesion loss and
reduction of stiffness occurs resulted to exponential disintegration. Similar behaviour of BSMs
with other aggregates plus 1% lime occurred on correlation test with MIST device testing
system. MIST test results presented in separate report included in Task 9.
4.4 Testing temperature
The testing temperature on this study was 25 o C, however field temperature in BSMs can vary
significantly. The effect of wet heated testing might result in a significant damaging effect in
terms of cohesion loss and stiffness reduction. However, moisture ingress and related damage in
South Africa will take place during rainfall period, where the air temperature does not exceed
30 o C. Therefore, as BSMs used in base or subbase layer temperature will not exceed 25 0 C.
During MMLS3 wet trafficking, the test temperature was controlled at 25 o C using thermocouples
attached to the briquette at Position 3 and 6 of the briquette layout. The thermocouple reading
was monitored intermittently during trafficking period.
4.5 ITS Testing
After the MMLS3 tests, further conclusive evidence of the materials distress due wet trafficking
could be observed upon removal of the trafficked briquettes and testing. The removal of
briquettes included precaution to avoid further damage. Thereafter, ITS test was carried out to
investigate the extent of distress on the BMSs due to wet trafficking performed. The
quantification of the reduction of tensile strength was measured from the wet (trafficked) and
dry (trafficked) briquettes. The Indirect Tensile Tests (ITS) was performed at the respective
number of briquette recovered from MMLS3 test. At least three (3) specimens from every type
of mix were tested. All ITS tests were performed at 25 0 C temperature. The ITS tests were done
at controlled displacement with applied rate of 50.8mm/min. The results of the ITS tests are
summarised in Table J.7, Table J.8 and Table 13Table 14.
Tensile Strength Retained (TSR) after wet and dry MMLS3 trafficking can be calculated as a Ratio
of average wet ITS over average dry ITS. The results of TSR presented in Table 15 above.
27