Effects Of Ageing On Mastics And Perforanmce Of Gap-Graded Asphalt Mixtures Subjected To Moisture Conditionings
Apart from realising and implementing sustainable approaches to construct asphalt pavement, a proper selection of materials is also crucial and can be a challenging task. The durability of asphalt pavements includes several aspects that can be related to the mechanical responses of materials, intera...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://eprints.usm.my/47430/1/Effects%20Of%20Ageing%20On%20Mastics%20And%20Perforanmce%20Of%20Gap-Graded%20Asphalt%20Mixtures%20Subjected%20To%20Moisture%20Conditionings.pdf |
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| Summary: | Apart from realising and implementing sustainable approaches to construct asphalt pavement, a proper selection of materials is also crucial and can be a challenging task. The durability of asphalt pavements includes several aspects that can be related to the mechanical responses of materials, interactions between structural layers, and the influence of non-load related mechanisms such as oxidation, moisture effect, and severe weather conditions. The main purpose of this study was to characterise and understand the effects of ageing on the performance of Gap Graded Asphalt Mix (GGAM) at a range of moisture conditions. To assess the performance of mixture in terms of fatigue cracking and rutting potential, the experimental works were divided into two phases. In the first phase, the effects of CaCO3 with OPC or TPOFA as additives on the rheological properties of bitumen penetration grade 60/70 at high and intermediate temperatures was measured using the Brookfield Rotational Viscometer and Dynamic Shear Rheometer. Then, the samples were prepared by using cubical shaped aggregate, bitumen penetration grade 60/70, and 6% calcium carbonate (CaCO3); with 2% Ordinary Portland Cement (OPC) or Treated Palm Oil Fuel Ash (TPOFA) as filler minerals and the performance of GGAM were measured from the Indirect Tensile Strength (ITS), Resilient Modulus (MR), Dynamic Creep (DCT), Hamburg Wheel Tracking (HWTT), Simple Performance Test (SPT), and Flexural Beam Fatigue test in the second phase. The fracture faces of the samples which were tested using ITS test were analysed using the 3D-image analysis technique. Statistical analysis employing the Analysis of Variance (ANOVA) was employed to analyse the results and to assist in characterising and understanding the material performance. The test results showed that all asphalt mastics exhibited a higher viscosity compared to the base binder. Although the addition of CaCO3+TPOFA increased the G*, it reduced the phase angle which is believed to be attributed to the enhancement of the stiffness and improved the rutting resistance of asphalt mastics. The results further demonstrated that the addition of CaCO3+TPOFA to the mixture had a significant effect on the properties of GGMA which led to the improvement of the mixture’s resistance against rutting and fatigue cracking. It was also found that the SPT and the wheel tracking test can capture the severity of rutting that is caused by the combination of densification and lateral flow deformation. The test results indicated that mixes containing CaCO3+TPOFA performed better and were less susceptible to permanent deformation. The aggregate skeleton within the gap-graded mixture played a crucial role as the main bearing body for the compressive forces. The fatigue resistance test results demonstrated that all samples exhibited good behaviour. It was observed that there was a slight reduction in the fatigue life of the aged specimens compared to the un-aged samples. On the other hand, the ITS and MR of long term ageing samples were higher than those of unaged samples due to the higher stiffness of the mix. |
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