Updating Bituminous Stabilized Materials Guidelines Mix Design Report Phase II

4. ANALYSIS AND DISCUSSION OF RESULTS
The objective of this section is to provide an overview on the findings of MMLS3 testing and
subsequent ITS testing on wet and dry trafficked BSMs. The results obtained in APT device
(MMLS3) and ITS used to establish possible correlation or trend between MMLS3 and MIST
device testing system. The relationships between these devices also provide an insight of
moisture related damage on different BSMs. Through the results, screening of the different
BSMs in terms of moisture susceptibility defined.
In an attempt to observe the performance of proposed MMLS3 test set-up for the BSMs, the
initial study tests conducted with different test variables. These variables include 680kPa tyre
pressure, 1.2kN wheel load, and 7200wheel per hour, with installation of vinite layer at the top
of briquettes. The additional tests however, were carried out at new testing variables to
correlate with the variables predetermined for the MIST device. The new variables were 420kPa,
1.8kN, and speed of 7200wheel per hour. The combination of new variables allowed acceptable
number load application of MMLS3 trafficking and correlation with MIST device testing system
on BSMs.
The study of different factors related to moisture damage on the BSMs was investigated. These
factors described in subsequent subsections.
4.1 Load application on BSMs
The impact of moisture on pavement performance differs depending on the type of pavement,
loading condition, temperature, and degree of saturation. A BSM in pavement layer is used as
base or subbase, in order to enable load distribution in the structure. The interaction of the
surface traffic and pore pressure developed in BSMs due to ingress of water is complex. In this
study, the MMLS3 test variables were scaled down to correlate with MIST device. Due to
reduction of tyre pressure and wheel load, the installation of vinite or rubber mat layer used to
ensure the pore pressure effect not reduced in the BSMs during trafficking. The installation of
vinite or rubber mat does not simulate field conditions, but merely minimises direct abrasion of
the wheels on the BSM-layer and help screening BSMs in terms of moisture related damage.
As outlined above, different BMSs were investigated during MMLS3 and MIST testing in the
laboratory. Figure J.17 present a comparison of BSMs performance on load application to failure
in wet condition, at 25 o C, 420kPa, 1.8kN, and speed of 7200wheel per hour.
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