Physico-mechanical and durability properties of new eco-material based on blast furnace slag activated by Moroccan diatomite gel

Natural diatomite, an amorphous siliceous rock, was used as a source of silica for the synthesis of a silicate gel to replace commercial sodium silicate gel in the synthesis of geopolymers from blast furnace slag at room temperature. Nine diatomite gels were synthesized by varying the diatomite content in the gel by 0, 10, and 15% and the NaOH molarity by 6 M, 8 M, and 10 M. The chemico-mineralogical and microstructural characterization results of the elaborated geopolymers showed that the blast furnace slag activation by diatomite gel under optimal conditions (8 M NaOH molarity and 10% diatomite) leads to a good dissolution and polycondensation of the precursor by forming amorphous gels of C-A-S–H type, as well as the mineral phase hydrotalcite, which are the same geopolymerization products detected in the case of the use of conventional silicate gel, and consequently, the obtaining of a geopolymer with interesting physical–mechanical characteristics: compressive strength of 42 MPa, density of 1. 61 g/cm 3 , ultrasonic pulse velocity of 3855 m/s. Thus, this new approach used in this work proved to be successful in reducing the cost and environmental impact of geopolymers.