Experimental investigation on compaction properties of sandy soils

In this research, an effort has been made to develop a correlation between standard and modified proctor compaction test parameters, i.e., maximum dry unit weight (gamma dmax) and optimum moisture content (OMC) of sandy soils. Standard and modified proctor along with classification tests were carried out on hundred and twenty sandy soil samples with different grain size distributions. Based on the test results, the soil samples were classified into various groups of medium to fine sand with non-plastic fines up to 45%. Regression analyses were performed on the experimental data and correlations were proposed to express modified Proctor parameters (gamma dmod and OMC mod) in term of standard Proctor test parameters (gamma dstd and OMC std). The validation of the proposed predictive correlations was done by using test results of another set of sandy soil samples not used in the development of the correlations. The results of the analyses showed that variation between experimental and predicted values of gamma dmod is within +- 4 % confidence interval and that of OMC mod is within +- 2.0 %. Further, based on the test results, an effort has been made to investigate the effect of fines (finer than 75 mu m) on compaction characteristics. It was observed that gamma dmax both in case of standard and modified proctor increases with increase in fines content up to 35% and beyond that it decreases. However, the value of OMC in both the cases decreases with increase in fine content. The correlations proposed in this paper may be very useful during the project preliminary/ pre-feasibility stages in the field of Geotechnical Engineering. (author)