Predicting Compaction Characteristics of Fine-Grained Soils in Terms of Atterberg Limits

Abstract

This study presents a set of regression models for predicting maximum dry unit weight $({\gamma _{{\text{dmax}}}})$ and optimum moisture content (OMC) of fine-grained soils in terms of their consistency limits. The empirical models were developed by performing experimental investigation on forty (40) natural fine-grained soils, encompassing a wide range of liquid limit (LL) and plastic limit (PL). The compaction characteristics were determined by conducting IS light compaction test (standard Proctor equivalent in Indian standards). Observation shows that ${\gamma _{{\text{dmax}}}}$ linearly decreases and in contrast, OMC increases in the same fashion with increase in LL or PL. However, in terms of regression coefficient, LL exhibits a superior correlation with ${\gamma _{{\text{dmax}}}}$ and OMC than PL does. The observed variation trend of compaction characteristics with LL and PL is affirmed by a few previous studies in the domain. A set of two independent models are finally developed for predicting ${\gamma _{{\text{dmax}}}}$ and OMC of soils taking both LL and PL into account. Reasonably good regression coefficients are obtained in case of both the models (R ² = 0.90 in case of ${\gamma _{{\text{dmax}}}}$ and R ² = 0.86 in case of OMC model). The models are validated by predicting ${\gamma _{{\text{dmax}}}}$ and OMC and comparing with actually measured values in a published study as well as present study. The root-mean-square error (RMSE) in case of ${\gamma _{{\text{dmax}}}}$ prediction is 2.1% against the measured values of present study and 7.4–7.5% against measured values in literature. The RMSE involved in case of OMC prediction model is 7% against present values and 17.5–28.2% against measured values in literature.