Waste glass as binder in alkali activated slag–fly ash mortars

This paper illustrates the application of waste glass powder as part of the binder in slag-fly ash systems activated by NaOH and NaOH/Na2CO3 activators. To evaluate the reaction kinetics, reaction products, mechanical properties, and durability performance of glass powder modified alkali activated slag-fly ash systems, calorimetry test, X-ray diffraction, FTIR, strength test, drying shrinkage tests, and carbonation test were conducted. From the isothermal calorimeter results, glass powder shows a higher reactivity compared to fly ash but still lower than slag. The reaction products of glass power modified samples exhibit an enhancement of polymerization degree of Si-O-T, observed in FTIR. As a consequence, higher drying shrinkage exists in glass modified mortars. The mechanical performance of different samples is mostly controlled by the Ca/Si of dry mixtures and activator type. After the slag-fly ash binder system was modified by the waste glass, a significant enhancement of resistance to carbonation was identified, especially for NaOH/Na2CO3 activated mortars, which show an increase of 300% on the carbonation resistance ability compared to the reference sample. The Na/(Si+Al) ratio of dry mixtures exhibits a positive correlation with carbonation resistance.