Feasibility of producing geopolymer binder based on a brick clay mixture

A brick clay mixture from a company localized in the north west of France is used for this study. The feasibility of producing geopolymer materials from a clay mixture was investigated. The final aim is to find a new application for this aluminosilicate material. One metakaolin (for a reference), the brick clay mixture, and the clay mixture calcined at two temperatures were compared after reaction with each of three alkaline solutions with different reactivity (the reactivity of each is defined). Physical, chemical, structural (FTIR and XRD) and thermal characterization (DTA) were first performed on the raw materials. Then, the structural evolution of the formed geopolymers was investigated using FTIR spectroscopy and XRD. Thus, this study demonstrates the feasibility of producing consolidated materials from a calcined brick clay (containing calcium oxides), which exhibits higher reactivity than brick clay. Plus, from a mixture of 25 wt% of less reactive materials such as ground brick clay and 75 wt% of reactive materials, it is possible to obtain geopolymer materials. FTIR study reveals the presence of a Ca2+ release phenomena, with a simultaneous polycondensation reaction for products based on calcined brick clay, which is different according to the silicate solution. Moreover, a link between [M++M2+] and the different networks formed in the samples based on calcined clay was found. Indeed, it appears that the concentration within the range 10.5-14 mol/l favors the geopolymer network formation.