Suitability of Laboratory Compaction Procedure for Secondary Materials

Abstract

The present study evaluates the suitability of the modified proctor test (MPT) using single and multiple batch compactions for two types of secondary materials: reclaimed municipal solid waste (RMSW) and MSW incinerated bottom ash (IBA). In the single batch (SB) technique, the same sample is re-compacted for each successive moisture increment, whereas in the multiple batch (MB) technique, a fresh sample is used for each moisture content. The composition and grain size analysis have substantiated the compaction results of the materials in concern. The maximum dry density values for RMSW were observed to be identical in both SB (1.70-1.74 gm/cc) and MB (1.71-1.75 gm/cc) compaction, indicating no effect of the compaction technique on RMSW. In contrast, SB (1.74-1.80 gm/cc) overestimates the compaction characteristics of IBA compared to MB (1.65-1.69 gm/cc). IBA experiences higher particle crushing in SB compaction, leading to an increase in fines content in each successive compaction phase, resulting in an inaccurate estimation of compaction parameters. Weak constituents like glass and sintered material make the coarse fraction of IBA susceptible to higher particle crushing than RMSW, which was also evident from the aggregate impact test. It is recommended to use the SB compaction for estimating compaction characteristics of RMSW, whereas MB compaction is appropriate for IBA. This study is essential to ensure appropriate field compaction control for using secondary materials in embankments and pavements.