Structural performance of asphalt blocks pavement as related to thickness, binder types, and joint width

Abstract

Asphalt block pavement is an innovative alternative to asphalt pavements. This study investigated the performance of asphalt paving blocks with a number of variables: block thickness, bitumen types and joint width between blocks. The effect of dynamic and static loads and their transfer from one block to another on the behaviour of asphalt block pavements were studied. Asphalt blocks were laid on sand bedding, but direct laying on a base course was also investigated. The experiments conducted in the laboratory were push-in test, pull-out test, and accelerated trafficking test. Two types of bitumen were used as binder to produce asphalt blocks: normal bitumen (60/70) and modified bitumen (PG 76) and different block thicknesses: 70 mm, 80 mm, and 90 mm. Asphalt blocks were laid in stretcher bond with various joint widths: no joint spacing, 2 mm, and 3 mm. The instruments of the push-in test and pull-out test were constructed within a steel box of 1.0 metre square; the push-in vertical load was increased from 0 to 30 kN on the samples of asphalt blocks. The accelerated trafficking loading test was conducted in a steel platform of 1.0 m × 5.0 m, the loaded wheel was moved over the pavement model and the deflection was taken at specific intervals. The results indicate that asphalt blocks have a great performance after being exposed to static load and dynamic load. The study shows that placing asphalt blocks directly on the base course resulted in uneven surface; therefore the bedding sand layer is a necessary component in the structure of asphalt block pavements. From the statistical results, the thickness of the block has insignificant impact on the structural performance. However, there is a trend that a change in block thickness from 70 to 90 mm decreases the deflection and displacement of asphalt block pavement which could be due to a greater frictional area and load transfer, thus increase the response of the pavement. The results also show the type of bitumen used in this study has insignificant impact on the structural performance. However, it has an impact on the compressive strength and density of the block. The finding reveals that placing blocks with no joint spacing is found to yield the best performance.