Effects and mechanisms of slag reinforced coal gangue geopolymers

This paper uses alkali activators with the modulus of 1.30 to prepare coal gangue geopolymers, thereby studying the reinforcement effects of slag content on coal gangue geopolymers. Besides, XRD, TG-DTG, and SEM are introduced to analyze changes in the microstructure and further explore the change mechanisms. The experimental results show that the compressive strength of coal gangue geopolymers increases with the increase in slag content. Compared to the P.O 42.5 pure cement paste, coal gangue geopolymers can obtain higher early strength. Besides, the 28d compressive strength of coal gangue geopolymers is greater than P.O 42.5 pure cement specimens when the slag content is 20%. The geopolymer products of slag-containing coal gangue geopolymers are C-(A)-S-H and N-A-S-H gels. The two kinds of gels, which are highly compatible, jointly constitute the network-like disordered structure of polymers. The XRD, TG-DTG and SEM results are consistent with the strength analysis results.