On the Compaction Characteristics of Soil-Lime Mixtures

Aim of the present note is to contribute to the optimization of the mix-design procedure of lime treated soils with particular reference to compaction characteristics. Seven soils with different plasticity characteristics and clay fractions are included in the experimental program, different amounts of quicklime and hydrated lime were added to the soils by wet mixing and then Standard Proctor compaction was carried out at different water contents in order to study the effect of lime treatment on compaction characteristics. Microstructural investigation was developed by means of scanning electron microscope. A general decrease in the maximum dry unit weight was observed together with a flattening of the Proctor curve. Also optimum water content changes due to lime addition. A factor that takes into account these modifications was defined and compared for several mix designs. Good correlations (confirmed by Fisher’s statistical test) between this factor and clay fractions of the soil to be treated were derived for 5% hydrated lime added. In addition, useful directions were retrieved analysing experimental results for soils treated with different types of lime in different proportions. Results contribute to have a preliminary idea of the effective mix design parameters, knowing the soil to be treated, helping, in this way, in possibly reducing the number of tests in the design phase.