Use of reservoir clays sediments as raw materials for geopolymer binders

Geopolymers represent an emerging class of materials synthesized by alkaline activation of reactive silico-aluminate precursors such as metakaolin and coal fly ashes. These precursors, often amorphous, can be dissolved in a strongly alkaline medium. A polycondensation reaction follows that yields a stable geopolymeric network. Among low cost or readily available raw materials, reservoir clay sediments are of interest. These materials come from periodical dredging of artificial lakes. In fact, the mean lifetime of artificial lakes is greatly shortened by the accumulation of sediments coming from the rivers feeding into them. Thus, periodical sediment removal is necessary in order to keep a satisfactory level of functionality. Removal and relocation of sediments causes several economic and environmental problems. This investigation focuses on the suitability of clay sediments as raw matter for geopolymer synthesis. The sediments were preliminarily characterized by XRD, thermal analysis and FT-IR. Then, as-received or calcined sediments were mixed with NaOH solution and the obtained geopolymer was studied in terms of phase composition and strength performance.