Development of green ternary-blended-geopolymers for multifunctional engineering applications

Abstract

Many industrial-wastes/clays, such as ground granulated blast-furnace slag (GGBFS), fly ash (FA), cement kiln dust (CDK), and metakaolin (MK), are employed in developing geopolymeric materials used in the construction sector. Accordingly, this work aims to find a green approach to benefit from the synergistic impacts of the precursors in developing ternary-blended geopolymers (TBGs; GGBFS/FA/CKD and GGBFS/MK/CKD) having multifunctional engineering applications. Five mixes were prepared: the control specimen (100 % GGBFS, S0) and the others contained different portions from GGBFS, FA, MK, and CKD. All mixes were cured in high humidity for up to 28-days. The impact of the TBGs’ mix-design on the fresh properties (workability and setting time), compressive-strength, pore-structure parameters, firing resistivity (200–900 °C), high dose gamma-radiation withstanding (1000–3000 kGy), and anti-microbial activity (against Aspergillus-oryzae, Aspergillus-fumigatus, Bacillus-Cereus and Salmonella-typhi) were investigated. Moreover, the phase composition (X-ray diffraction (XRD) and thermogravimetric analysis (TGA/DTG)) and microstructure (scanning electron microscope (SEM/EDX)) were studied. The obtained results demonstrated that CKD greatly impacts the lowering of workability and shortening of setting time due to high fineness/alkali-content in contrast with FA and MK. The obtained strength values by TBGs after 28-days ranged from 46.3 to 52.2 MPa. TBGs have significant strength retention and resistance to higher temperatures and higher doses of gamma-radiation compared to control due to the formation of highly-stable zeolitic phases. The S0 specimens cannot inhibit the growth of Salmonella-typhi in variance with TBGs that inhibit the growth of all micro-organisms owing to the presence of Fe2O3 and TiO2 in the matrix.