ABSTRACT
For best mechanical performance, loose mixture of asphalt concrete needs to be compacted. The achievable density of mixture depends on several variables including aggregate properties (source, type, texture, shape and gradation), binder properties (grade, content) and process (compaction temperature, compaction method, compaction energy). Among all the impact compaction methods, Marshall Mix Design is more widely used. During the impact method of compaction, aggregate particles may disintegrate due to the impact load, and abrasion. This disintegration may affect the aggregate gradation and volumetric properties of mixtures. In this work the effect of impact compaction in aggregate degradation and subsequent volumetrics using is presented. The four different mixtures using two binders (neat binder-VG 30, modified binder-PMB 70) and two aggregate gradations were designed using Marshall mixture design. These mixtures were compacted using 4 inch and 6 inch diameter Marshall moluds using standard and modified Marshall compactor for different levels of compaction. The aggregates from the compacted specimens were recovered and changes in aggregate gradation were examined. The statistical analysis indicates that the compaction level, aggregate type and size of mould affect the degradation of aggregates and mixture volumetrics significantly.
