Evaluation of the combined effects of long term aging and moisture damage on asphalt mixture incorporating cubical aggregates and zycotherm
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Date
2018-06
Authors
Tan, Shin Ru
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Abstract
Warm mix asphalt (WMA) is a sustainable technology developed to lower the
mixing and compaction temperatures but can be prepared using conventional asphalt
plant and paving machineries. In terms of environmental and sustainability aspects,
WMA can effectively reduce greenhouse gas emissions. Due to its lower production
temperature, WMA is more prone to moisture damage due to incomplete drying of
aggregate thus results in trapped moisture. Excessive intrusion of moisture into the
asphalt pavement would deteriorate the pavement quality and have adverse impact on
asphalt pavement. A warm compaction additive from India named Zycotherm was
added to produce WMA and its effectiveness as an anti-stripping agent was
investigated. To simulate the actual condition on site, the asphalt mixtures were
subjected to simultaneously long term aging and moisture damage. The performance of
WMA and HMA were evaluated in terms of compactability, workability, tensile and
shear strengths. From the investigation, WMA can be more easily compacted and more
workable compared to HMA. WMA exhibited better moisture resistance after subjected
to moisture conditioning. The utilization of cubical aggregates in asphalt mixture
showed better performance in terms of tensile and shear stresses. From image analysis,
WMA incorporating cubical aggregates demonstrated lower percentage adhesive
failure which proved the effectiveness of Zycotherm. The formation of fractured
aggregates was primarily due to the aggregate shape instead of aggregate orientation.
This is because most of the broken aggregates were elongated or flaky normal
aggregates that breaks easily along their weak plane when subjected to applied loads.
Analysis on the aggregate gradation after compaction and performance tests proved that
cubical aggregates degraded less than normal aggregates.