Influence of superplasticiser on cement-stabilised self-compacting earth

Abstract

Cement-stabilised self-compacting earth (CSCE) is a mixture of soil, water, stabiliser and chemical admixture, with sufficient fluidity to mould earth walls and structures without the need for mechanical densification. The application of the CSCE technology demands a better understanding of the influence of polycarboxylate-based superplasticiser in the mechanisms of particle dispersion, and the microstructure formation of the CSCE. Therefore, for two soil mixtures, sandy soil + cement + water + admixture and clayey soil + cement + water + admixture, the following tests were applied: calorimetry, thermogravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, compressive strength and water absorption capacity. The results demonstrated that the use of superplasticiser in the CSCE exhibits efficiency of fluidity, mobility, segregation control and exudation control in the mixture. Regardless of the soil type, the influence of the superplasticiser on the CSCE mixtures is more relevant to aspects such as the action of electrostatic dispersion of soil and water and of the particles that induce steric hindrance; also the adsorption reactions of admixture by clay minerals are discrete in the CSCE, resulting in a system with physicomechanical behaviour stabilised and compatible for earth-based construction through the use of superplasticiser in the range of 0·8–1·6 and minimum water/soil ratio with proximity to the liquid limit.