Soil-Cement Pavement Layer Compaction with Time: Microstructural and Physicochemical Assessment

A literature review reveals timing of soil-cement construction activities, while considered for decades, is an opportunity for improvement. Companion work recommended changes to AASHTO T134 Standard Method of Test for Moisture-Density Relations of Soil-Cement Mixtures and the objective of this paper is to supplement those efforts by performing physicochemical and microstructural testing on the same mixtures to further evaluate timing implications of soil-cement compaction sequences. Some soil-cement combinations lose meaningful density when compaction is delayed (even within what would often be considered acceptable time windows), while others do not. Generally speaking, this paper showed that soil with low cation exchange capacity, low-aluminum levels, low-clay content, and high-silicon content were least susceptible to compaction delay. The paper also showed that the recommended changes to AASHTO T134 that are based on Proctor testing were more likely to be effective than physiochemical or microstructural testing for capturing compaction delay.