Impact of compaction method on mechanical characteristics of unbound granular recycled materials

Laboratory testing methods are constantly being developed to simulate true field conditions in controlled laboratory environment. The aim of laboratory testing methods is to reproduce specimens which accurately replicate field performance in terms of mechanical behaviour of pavement materials under applied loads. Compaction is the most common soil stabilisation technique in ground improvement and pavement construction works. Among the available laboratory compaction methods, the impact method followed by the static method are the most commonly used procedures. Since the nature and approach of these two compaction methods are fundamentally different, an investigation on the effect of using these techniques on the mechanical performance of pavement materials prepared by each of these methods is essential, so as to better understand both these compaction methods. In this regard, two types of recycled construction and demolition (C&D) materials suitable for pavement applications, namely crushed brick (CB) and recycled concrete aggregate (RCA) were selected. Laboratory specimens were prepared using the above-mentioned procedures. Different aspects of geotechnical characteristics of the specimens, including aggregate breakage, changes in soil–water characteristics, stiffness, and resilient characteristics, were investigated. The outcomes of this research indicate that the influence of method of compaction must be considered when interpreting the laboratory test results for field design purposes.