New geopolymer preparation methods and its application by recycle of double-waste: ground granulated blast furnace slag and fly ash

This article mainly studies new geopolymer preparation methods by recycle of double waste:ground granulated blast furnace slag (GGBFS) and fly ash as geopolymer precursor, through different mass ratio of GGBFS and fly ash, to prepare geopolymers by alkali activation, the samples is cured at ambient temperature and the mechanical test is carried out together with the analysis of XRD, SEM and EDS to research the mechanism of strengthening and geopolymerisation. After analysis we find that the sample prepared by 30% mass ratio of GGBFS have good initial strength and short setting time, as well as best mechanical performance, which is attributed to moderate Ca2+ introduction accelerates the speed of geopolymerisation and the reactants of N-A-S-H gel, C-A-S-H gel and hydrated C-S-H help to bridge the gaps between the different hydrated phases, unreacted particles and matrix, result in a homogeneous and compacted geopolymeric sample. When GGBFS mass ratio above 50%, the mechanical of samples is deteriorated due to too much hydrated calcium containing compounds are formed and covered on the unreacted GGBFS particles surface to block further geopolymerisation. The acid attack test and water resistance test are carried out to analysis the durability between 30% GGBFS introduced geopolymer and ordinary Portland cement (OPC). In additional, a field application in case of 30% GGBFS introduced geopolymer grouting repair material indicated desirable construction based on visual observation and ground-penetration radar scanning.