Investigation on the performance of bond strength between pavement layers has gain serious attention from researchers worldwide. Typical methods to prepare the double layered testing specimen at laboratory scale is to follow the Marshall procedure or to perform coring on constructed field scale test lanes. For specimen prepared with Marshall procedure, binder course loose mix is compacted at double faces first prior to the application of wearing course loose mix in the compaction mould and perform the compaction of the loose wearing course later. This paper focused on the specimen prepared using Marshall procedure where the upper wearing course is subjected to single face compaction. The feasibility of single face compaction is investigated and the relevant amount of compaction blows is determined to achieve sufficient thickness and degree of compaction. Aggregate is proportioned to achieve a target thickness of 35, 50 and 65mm, at an allowable limit of ±1 mm. For the tested mix incorporating dense graded, open graded and gap graded mix, each mix managed to achieve the required degree of compaction at satisfactory thickness with respective compaction blows.
Quality of bond between layers of asphaltic concrete course is a key element to ensure the performance of a modern asphalt pavement. A proper interlayer bond ensures the structural integrity of the pavement and prevents possible distresses from occurring within the designed service life. In Malaysia, delamination is a common distress related to insufficient degree of adhesion though slippage failure can be occasionally encountered. Generally, bond development is closely related to the design factors and construction factors. This paper however focused on the construction factors only, hoping to provide some useful information which might be overlooked by the contractors during construction but is of extreme important especially in enhancing the bond development in the asphalt layers. The construction factors in particular interest discussed in this paper include curing time of asphalt emulsion, surface condition of a pavement and technology and quality of workmanship and construction. It is important to note that both design factors and construction factors are inter-related in optimizing the degree of adhesion. Thus, all factors need to be carefully identified and fulfilled in order to maximize the bond strength between pavement surfacing layers for a better quality and longer service life of pavement in Malaysia.