Papers by Author: Julien Soro

Abstract: Consolidation of cements and geopolymers can be explained by the formation of alkali silicate or alumino-silicate gels formed in situ during materials setting. To control such a system, a study concerning the use of sodium silicate gel as binder was initiated to manufacture consolidated materials with different size distribution of silica. The gels used as precursor of binder were synthesised by acidifying with hydrochloric acid, a concentrated sodium silicate. Consolidated materials were obtained by mixing the previous solution before gelation with granular materials (fine silica powder and sands). The existence domain of consolidated materials depends on the size distribution of sand. Consolidation of material is strong when the amount of silica is high. This result suggests a dissolution / precipitation reaction between gel and silica. Therefore, consolidation could be explained by the dissolution of small particles of silica and their precipitation into the grain boundary of sand. Mechanical properties are closed to those of cement materials.

Abstract: Progress of fuse technology to reduce cost and to protect environment requires the understanding of physicochemical phenomena that govern the consolidation of the sand with alkaline silicate solution. In this context, this work concerns the agglomeration behaviours of sand with alkaline silicate solution. The effects of sand particles size and concentration of solutions are investigated at various temperatures. The main objective is to understand the interactions between sand and this alkaline solution during the impregnation of sand with sodium silicate solution and the drying leading to the consolidated materials. Various investigations were performed, thermogravimetrical and differential thermal analysis (TG/DTA), gravimetric analysis of wet sample, scanning electron microscopy (SEM) and compressive strength test on dry samples. The results show that agglomeration is affected by silica grains size distribution and temperature. Bonds strength between the grains increase with decreasing grain size and increasing temperature.