Efficacy of pond ash (PA) combined with ground granulated blast furnace slag (GGBFS) in producing cement-less mortar

Abstract

In this research, an attempt has been made to produce cementless construction materials utilizing industrial wastes, e.g., pond ash (PA) and ground granulated blast furnace slag (GGBFS) as binder materials, followed by alkali activation using a mixture of sodium hydroxide (NaOH) and sodium metasilicate (Na2SiO3) solution. In this study, two types of samples, i.e., alkali-activated paste (AAP) and alkali-activated mortar (AAM) were prepared. The AAP samples were prepared to evaluate the setting times, hydration behavior (by monitoring hydration temperature as the function of time), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Analyzing the results, it is revealed that AAP samples sets within the standard time range (initial and final setting times are 55 and 105 min, respectively). The compressive strength analysis of the AAM sample (prepared using the same binder composition with a binder to fine aggregate ratio = 1: 3) is measured to be ∼12 MPa after 28 days of ambient curing. The setting and the hardening ability of AAP and AAM samples appear to be due to the pozzolanic reaction of PA and GGBFS with alkali activators, which is verified by the formation of hydrated products as demonstrated by the FTIR, XRD, and SEM analysis. Finally, a comparative study has been done to assess the reduction of CO2 emission for the use of PA-GGBFS binary mixture in the construction sector replacing the cement.