A study on the Durability and Hydration of Geo-polymer Concrete with Slag,Fly Ash, Polysilicon Sludge

Abstract

Geopolymer concrete has been proposed as an alternative to reduce the amount of carbon dioxide emitted during cement production and as a way to recycle industrial byproducts. In the case of geopolymer concrete, the use of an alkaline activator is essential and studies have been carried out to supplement this. Polysilicon sludge is emerging as a new SCM material due to the large supply and demand of abundant CaO, Na and Cl ions. However, physical and chemical evaluations of polysilicon sludge have rarely been performed. Thus, the physical and chemical properties were evaluated using the mix deisgn method in order to experiment the applications of polysilicon sludge. KOH, NaOH, and Na2SiO3 alkali activators were selected as the basic process, and the mortar strength development according to the incorporation amount of polysilicon sludge was studied. According to the amount of polysilicon sludge mixed, the strength of mortar showed the highest compressive strength at 10 ~ 20% admixture. Therefore, the mix design of the geo-polymer concrete was determined according to the result of the mortar experiment. The penetration depth of chlorine ions decreased by 12 ~ 20% depending on the amount of polysilicon sludge mixed, and hydration products were confirmed using SEM & EDS, XRD, TGA-DSC and FT-IT analysis. In addition, TGA-DSC analysis of the fabricated samples revealed three abrupt weight reduction periods with an increase in temperatures. Also, the rate of reduction for each section was 48%, 60%, and 24% of the total weight. In this study, the intensities were determined through the determination of the amount of the admixture, but the intensity of some samples was relatively small for the mixing ratio of 20%. Therefore in order to verify the changes in the properties of concrete through physical and chemical analysis, various studies are needed.