Restriction of Volume Change and Improvement of Strength Properties of Problematic Soils Using Nano-natural Additives

The objective of this paper is to investigate the effect of using nano-additives on some geotechnical properties of expansive soils. The investigated soils were quarried from three different sites in the south of Syria. The nano-additives were nano-natural pozzolana (NVS) and nano-lime (NL). NVS was added at three percentages, i.e., 0%, 1% and 2%, whereas NL was added at 0.6%. The examined geotechnical properties were Atterberg limits, swelling and shrinkage properties, unconfined compressive strength (UCS), California bearing ratio (CBR) and shear strength. From the test results, the positive effect of adding NVS to the original soil has been clearly seen. Plasticity index (PI) was reduced by more than 50% when 2% NVS was added. Further, all investigated properties have significantly been improved when NVS and NL were added together, i.e., UCS, CBR and shear strength characteristics increased to more than twice, 20-fold and about 50%, respectively, when compared with those of the original soil. Some relationships among the soil characteristics were also developed. Thus, one can predict, for instance, the CBR value from the knowledge of UCS' result, which is easy to be obtained. Advanced technics such as SEM and EDX were employed in the current study as well. The microstructural analysis revealed that cementitious compounds could be easily traced in all treated soil mixtures, particularly those containing both NVS and NL.