Waste glass as a precursor in alkaline activation: Chemical process and hydration products

This paper discusses the results of alkali-activating waste glass in pursuit of a new type of alkali activated materials (AAMs). Waste glass pastes were prepared with different alkaline activators (NaOH, NaOH/ Na2CO3, sodium silicate hydrate and KOH) with different concentrations and cured for 20 h at 85 C and at 99% or 6.5% relative humidity to assess the effect of these variables on paste mechanical strength and microstructure. Compressive strength performance was better at the higher alkaline concentrations and when the pastes were cured at low relative humidity (6.5%), which induced low porosity (MIP) and high specific surface (BET). Irrespective of the type of activator or curing process, the main reaction product was a Si-high, Al-low gel. As a raw material for alkaline cement manufacture, waste glass delivered compact, high-strength cementitious skeletons.This research was funded by the Ministry of Economy and Competitiveness under projects BIA2010-15516 and BIA2013-47876-C2-1-P and the Spanish National Research Council under project PIE201460E06. The authors wish to thank Eduardo Torroja Institute for Construction Science technicians Alfredo Gil, Francisco Morales and Patricia Rivilla for their assistance with the laboratory trials