Crystallization‐induced stabilization of foam glass aggregates for heat‐insulating concrete

Abstract

Resistance of the porous glass‐based aggregates to alkali‐silicate reaction (ASR) was the focus of this study. ASR was studied in mixtures of aggregates with water alkali solutions simulating alkali media of row concrete. Granular foam glass with homogeneous glass in the pore walls is ASR‐active, which leads to the leaching of glass and to the formation of hydrated Na‐silicate gel, Ca‐silicate, and aluminosilicate on the aggregate surfaces. Mitigation of ASR‐activity in granular foam glass was achieved by thermo‐induced crystallization (850‐900ºC) of micro‐ and nanoscale crystals (Na4CaSi3O9 and/or Na2Ca3Si6O16) in the pore walls with the formation of granular glass‐ceramic foams. The main characterization methods were scanning electron microscopy, x‐ray powder diffraction analysis, x‐ray fluorescence, atomic emission spectrometry, and pH analysis.