Microstructure, geotechnical and mechanical characteristics of quicklime-lateritic gravels mixtures used in road construction

Microstructure of quicklime-lateritic gravels mixes, containing up to 8 wt.% quicklime, was investigated by using X-ray diffraction, infrared spectrometry, differential thermal analysis, scanning electron microscopy and energy dispersive spectrometry. Geotechnical and mechanical properties of the mixtures were also measured. Quicklime additions resulted of reduction of clayey fraction, plasticity index, methylene blue value and maximum dry density and the increasing of optimum moisture content. The results showed also that quicklime admixtures resulted in the formation of calcium silicate hydrate type I (C-S-H (I)), portlandite and calcite. This CSH (I) was formed through the pozzolanic reaction between a part of the kaolinite and hydrated lime in the basic medium. Moreover, C-S-H (I) marked crystallization with curing time and observed for the quicklime amounts (<= 3 wt.%), contributed to the improvement of mechanical properties. These lime modified lateritic gravels are convenient for base course in road geotechnical applications. (C) 2011 Elsevier Ltd. All rights reserved.