Evaluation of Structural Performance of Concrete with Ambient-Cured Alkali-Activated Binders

Enormous global CO2 emissions associated with cement production necessitates the use of sustainable cementitious alternatives. Alkali-activated binder (AAB) which utilizes industrial wastes as precursors is a promising substitute for cement. To promote the practical use of AAB concrete, this paper presents an investigation on the mechanical and microstructural properties of ambient-cured AAB concrete. Fly ash/slag ratio is varied and the optimum mix is proposed based on compressive strength test results. Pull-out test is performed to evaluate the bond strength of ambient-cured reinforced AAB concrete. The specimen-level tests are supplemented with results from X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) along with energy-dispersive spectroscopic (EDS) analysis of the AAB paste samples. This is done to corroborate the microstructural characteristics with the mechanical properties at specimen-level. Fly ash: slag ratio of 70:30 is recommended as the optimum proportion considering both strength and economical aspects. Incorporation of slag results in the formation of the additional reaction products, refining the pore structure and enhancing strength. The AAB mix with fly ash: slag ratio of 50:50 exhibits the highest compressive strength and bond strength.