Variability in Construction of Cement-Treated Base Layers

Construction factors most correlated to specific mechanical properties of cement-treated base (CTB) layers were identified. Construction factors that exhibit comparatively high variability within individual construction sections of the two pavement reconstruction projects included in this study were determined. In addition, differences between construction sections tested in this research were evaluated. Researchers collected extensive field and laboratory data, which were analyzed using several statistical techniques. The results of this analysis suggest that reduced spatial variability is needed in reclaimed asphalt pavement (RAP) content, cement content, and time between mixing and compaction, which were all identified as important predictors of CTB strength in this study. For full-depth reclamation projects, milling plans should be used to achieve improved uniformity in RAP content, and inspection protocols for encouraging improved control of cement content during construction should be implemented to ensure high-quality work. Compaction should be performed as soon as possible after mixing to minimize the adverse effects of cement hydration on the ability to achieve maximum dry density in the field. Minimizing variability in construction of CTB layers will ultimately lead to higher-quality pavements that more consistently meet design expectations.