High performance cementless composites from alkali activated GGBFS

Abstract

Some of the thermally activated minerals and pozzolans were generally preferred in the production of geopolymer and/or alkali-activated composites as unary, binary, and ternary mixtures. The general trend is to use Ground Granulated Blast Furnace Slag (GGBFS) as binary or ternary mixes in the production of alkali-activated composites. However, GGBFSs have preferred the only binder in this study. Alkali-Activated Concrete (AAC) specimens were produced by using sodium hydroxide and sodium silicate aqueous solutions in three different molarity values (8, 10, and 12 M) for the formation of activation. For each mixture, three different activation temperatures, 25 °C (ambient temperature), 60 °C and 90 °C for 18 h, were applied. After this process, the specimens were kept under laboratory conditions (25 ± 2.5 °C) for 90 days to gain strength. Then capillary water absorption, density, Dynamic Modulus of Elasticity (DMoE), compressive strength, splitting tensile strength, and abrasion resistance tests were performed on the specimens. Furthermore, microstructure analyses were performed on the selected specimens. In the conclusion, AAC production was able to achieve using 100% GGBFS. High strength cementless concretes with a compressive strength of 82.32 MPa could be obtained by using GGBFS, which is a waste material. Besides, AAC with an abrasion value of 3.86% by weight was obtained in the specimen coded M12T60.