Updating Bituminous Stabilized Materials Guidelines Mix Design Report Phase II
Moisture Sensitivity: Part II (Validation) - Asphalt Academy
Moisture Sensitivity: Part II (Validation) - Asphalt Academy
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findings of the moisture damage that observed through MIST conditioning. The setting for<br />
loading pulse duration and pressure of the MIST apparatus was influenced by the load duration<br />
and stresses of the wheel loads applied to the materials by the MMLS3 APT device. Therefore, a<br />
rational analysis should be possible.<br />
1.3 MMLS3 Accelerated Pavement Testing device<br />
The scaled testing of pavement structures and surfacing is becoming a standard in the industry.<br />
This is due to the advantages associated with evaluating and grading of the asphalt mixes<br />
proceeding to construction, (Walubita et al., 2002). The development of the Model Mobile Load<br />
Simulator Mk3 (MMLS3) contributes significantly to Accelerated Pavement Testing (APT)<br />
method. The performance prediction of a pavement tested for rutting, fatigue, and susceptibility<br />
to moisture damage is possible. All of these failure mechanisms can be evaluated in the field i.e.<br />
under full-scaled conditions or in a laboratory under controlled conditions. In the laboratory, all<br />
the variables that have an influence on the properties of the pavement materials can be<br />
controlled during MMLS3 testing. The need for the development of standardised test protocols<br />
for testing BSMs with the MMLS3 arises to make certain that the result that produced is<br />
reasonable and comparable. A standardised testing platform ensures uniformity in results and<br />
increases the confidence in the results.<br />
The MMLS3 consists of four axles and each axle has a 300mm diameter inflatable pneumatic<br />
wheel on it that circulates in a vertical closed loop. The wheels are supported in bogies that<br />
linked by a continuous chain. The wheels are powered by an electric motor that drives a drum,<br />
which draws the wheels over the testing bed. The MMLS3 can also apply lateral displacement<br />
(wander) of plus or minus 80mm around the central axis.<br />
The four wheels are loaded by means of a swing-arm and a spring. The four wheels exert the<br />
load on specimens underneath the MMLS3. The speed of the wheels controlled at maximum of<br />
2.5m/s, which is equal to 7200 wheel loads per hour. The testing conditions are controlled, and<br />
it is possibility to do tests at temperatures within a range of 0ºC to 60ºC. Figure J.1 provides an<br />
illustration of the MMLS3 test set-up.<br />
Figure J.1: MMLS3 in testing mode<br />
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