Understanding the strengthening of a lateritic “geomimetic” material

Abstract

The present work aimed to investigate the interactions that control the strengthening of “geomimetic” materials. The raw lateritic clay used mainly contained kaolinite, goethite, quartz and hematite. The processing involved a 24h-reaction with fulvic acid followed by neutralization with lime or with NaOH prior to the curing at 60°C for 18days under water saturated atmosphere. The compressive strength and thermal conductivity after consolidation were respectively 0.7MPa and 0.19Wm−1K−1 for lime-based products, and 0.78MPa and 0.3Wm−1K−1 for soda-based products. The latter exhibited low durability in water. Such differences could be related to the high degradation of kaolinite particles when using NaOH, leading to the formation of sodalite, cancrinite and nontronite, which phases did not act as binder. Cementitious CAH and CSH phases were obtained when using lime. Rheological measurements performed on lime-based samples indicated that a shear-thinning behavior prevails up to the 7th day of curing. Above this period, the samples reached a determinant step whereby a solid-like behavior became predominant. The occurrence of binding precursors during the first 7days of curing conducted to a progressive increase of the yield stress and consistency from 1 to 53Pa and from 0.2 to 2.3Pas, respectively.