The Effect of Heavy Metal on the Static and Dynamic Performances of Clay Sand

Abstract

Poisoning of soil and groundwater resources is among the current major environmental issues worldwide. One effective way to stop the spread of pollutants and improve soil’s capacity for adsorption is to use natural and inexpensive adsorbents. In this respect, the soil environment can be improved by the addition of zeolite and rice husk ash (RHA). This study examined the behavior of a sand mixture with 20% kaolinite or 20% bentonite in both uncontaminated and contaminated [with Pb(NO3)2] states. Two classes of clay minerals were considered: kaolinite and bentonite. The impact of the adsorbent on the strength performance of the contaminated soil was examined by removing 10% of the clay particles and replacing them with zeolite or RHA adsorbents. Triaxial dynamic and bender element tests were carried out to explore the dynamic behavior of contaminated soils and the liquefaction resistance of the samples polluted with Pb(NO3)2, respectively. The results show that by reducing the heavy metals concentration Pb(NO3)2, the ultimate strength of sand mix with 20% bentonite increased by 40%–50%. In addition, the ultimate strength increased in polluted and noncontaminated situations by adding zeolite or RHA to the soil. The results of triaxial dynamic tests demonstrated that liquefaction resistance was reduced by increasing the contamination concentrations in both the mixes without and with adsorbent. Furthermore, the initial/maximum shear modulus (G0/Gmax) decreased as the adsorbent content increased in both contaminated and noncontaminated states.