Quantifying the accuracy of roller segmented compactor in simulating field compaction

Laboratory simulation of field compaction is essential to accurately predict pavement performance. Several studies have shown that in the laboratory, roller compaction better simulates field compaction than the traditional compaction methods such as impact and gyratory compaction. This study aims to quantify the simulation of field compaction in the laboratory using a roller segmented compactor (slab compactor) based on density and Indirect Tensile Strength ratio (ITSR) tests for a Dutch AC11_surf mixture. Using a reverse order approach, the field compaction of this mixture was first monitored on a local construction site. Asphalt mix temperature and energy input (from the roller) were identified as the critical factors affecting compaction. Hence the core temperature of the asphalt mixture, number of roller passes, type of roller pass (static or dynamic), type of roller and the field density after each pass were recorded at various locations. Almost simultaneously, the field compaction strategies were adapted and simulated in the laboratory using the slab compactor with the asphalt mixture being sourced from the same batch at the asphalt plant. Cored samples were obtained from the field and the laboratory; their densities measured and ITSR tests performed. The results of the field and the laboratory compaction comparison based on density, ITSR and ITS values, shows using a slab compactor results in 3% higher density and 13% higher ITSR values on an average. This shows that using a slab compactor enhances the properties of the mixture compared to what can be found in the field. Hence, when using a slab compactor for predicting pavement performance these magnitudes of variation must be considered. In addition, the test results of samples from the slab compactor were then compared using the Analysis of Variance (ANOVA) to substantiate the influence of temperature and energy input. The variation of these two parameters were found to have significant impact on the density and ITSR results of the samples from slab compactor.