Two iron-rich clayey materials (L1 and L2, with the main difference being the level of iron accumulation) have been studied for their suitability as solid precursors for inorganic polymer composites. L1, with the lower iron content, was calcined at 700°C for 4 h and used as replacement, in the range of 15–35 wt%, for both raw laterites in the formulations of geopolymeric composites. The different mixtures were activated with a highly concentrated alkaline solution containing sodium hydroxide and sodium silicate. River sand with semi-crystalline structure was added to form semi-dry pastes which were pressed to appropriate shape. X-ray diffraction, Infrared spectroscopy, Scanning Electron Microscopy and Mercury Intrusion Porosimetry results demonstrated the effectiveness of the calcined fraction of L1 to act as nucleation sites and extend the geopolymerization to the matrix composites. A highly compact matrix with low porosity and good stability in water, together with a strength comparable to that of standard concretes was obtained allowing for conclusions to be made on the quality of laterites as promising solid precursor for sustainable, environmentally-friendly, and cost-efficient structural materials.

Lateritic soils are formed in the tropics through weathering processes that favor the formation of iron, aluminum, manganese and titanium oxides. These processes break down silicate minerals into clay minerals such as kaolinite and illite. Iron and aluminum oxides are prominent in lateritic soils, and with the seasonal fluctuation of the water table, these oxides result in the reddish-brown color that is seen in lateritic soils. These soils have served for a long time as major and sub-base materials for the construction of most highways and walls of residential houses in tropical and sub-tropical countries of the world. Civil engineering applications of these lateritic soils are continually being developed with the use of different types of stabilizers. The stabilized soil-based products are as such viewed as environmentally-friendly and low-cost energy materials for sustainable building applications. This work aims at presenting a global view of what has been done in the field of lateritic soil improvement for construction purposes in tropical countries such as Cameroon. This shall be discussed through the presentation of the structure, composition and properties of lateritic soils, the various ways of improving their properties for construction purposes, the properties of products obtained and other prospects.