Evaluation of a Laboratory Asphalt Rotary Compactor
Several studies have shown that Marshall Compactor, California Kneading Compactor and Gyratory Compactor, the most conventional compactors, are not able to produce laboratory specimens that can truly represent the mixtures compacted in the field. However gyratory compactor fairly gives good simul...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English |
| Published: |
2009
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| Online Access: | http://psasir.upm.edu.my/id/eprint/7362/1/FK_2009_51a.pdf http://psasir.upm.edu.my/id/eprint/7362/ |
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| Summary: | Several studies have shown that Marshall Compactor, California Kneading
Compactor and Gyratory Compactor, the most conventional compactors, are not able
to produce laboratory specimens that can truly represent the mixtures compacted in
the field. However gyratory compactor fairly gives good simulation of the field roller
compactor but no universally approved laboratory compactor has been developed to
compact slabs for the wheel tracking and fatigue test. Compacting and preparing
more than one sample at the same time is another matter of concern which these
conventional compactors cannot achieve. Hence, a suitable laboratory compaction
procedure is inevitable. Rotary compactor, a laboratory roller compactor was
developed by researches from Universiti Putra Malaysia (UPM). This study was
conducted to evaluate the performance of rotary compactor as a laboratory asphalt
compactor and incorporated three objectives: to establish a laboratory protocol
including procedures and standards for using the UPM rotary compactor, to evaluate
the consistency of SMA slabs in terms of thickness and frictional resistance
properties, and to validate the use of UPM rotary compactor in achieving the SMA mixtures’ requirements for bulk specific gravity, voids, Marshall stability and flow,
resilient modulus and resistance to degradation. To compact a rotary slab to the
desired thickness of 65 mm and 4% air voids, the applied pressure was recommended
to start from 0 bar (as pre compaction) and stop at 1.5 bar with intervals of 0.25 bar.
For each value of applied pressure, 6 number of passes (rotations) were needed (3
passes per each direction). The speed of rotation was recommended to be fixed on 10
Hz (3.29 RPM). Based on checking 315 points of three slabs to measure the
thickness and the statistical analysis of these three slabs, the overall thickness of the
slabs was almost uniform along the slabs. According to analyzing the performance of
132 core specimens it was concluded that rotary compactor was able to produce slabs
with uniformly distributed properties such as volumetric properties, Marshall
stability, flow and resilient modulus. Finally a degradation study was carried out to
check and evaluate whether the aggregate structure was changed during the mixing
and compacting. It was found that two aggregate fractions (12.7 mm and 9.5 mm)
were affected and crushed during mixing and compacting procedures. To compensate
the observed loss percentages a value called weight factor was introduced to provide
the loss of materials. |
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