Resistance and swelling of Tabriz marl soils stabilised using nano-silica and nano-alumina

Abstract

The effects of nano-silica (NS) and nano-alumina (NA) additions on problematic marl soil in Tabriz, Iran were investigated. Marl soils constitute the foundations for most projects in Tabriz. Due to water absorption, these soils are liable to volume change, leading to instability risks in the foundations. Various physical and chemical methods have been employed to stabilise these soils. In the present study, for the first time, reconstructed samples of Tabriz marl were stabilised with various percentages of NS and NA, which have fewer negative environmental effects compared with ordinary additives such as Portland cement or lime. Soil swelling behaviours were evaluated experimentally using tests for Atterberg limits, density, free swelling, swelling pressure, California bearing ratio (CBR) and direct shear. Field emission scanning electron microscopy and X-ray powder diffraction analyses were conducted at curing times of 1, 7 and 28 days. It was found that NA had a greater effect on reducing the swelling of stabilised samples than NS. However, NS had a greater effect on increasing the strength (CBR).