Use of fine glass as ASR inhibitor in glass aggregate mortars

Demand for recycled glass has considerably decreased in recent years, particularly for mixed glass. Glass is cheaper to store than to recycle, as conditioners require expenses for the recycling process. In order to provide a sustainable solution to glass storage, a potential and incentive way would be to reuse this type of glass in concretes. Depending on the size of the glass particles used in concrete, two antagonistic behaviours can be observed: alkali–silica reaction, which involves negative effects, and pozzolanic reaction, improving the properties of concrete. The work undertaken here dealt with the use of fine particles of glass and glass aggregates in mortars, either separately or combined. Two parameters based on standardised tests were studied: pozzolanic assessment by mechanical tests on mortar samples and alkali-reactive aggregate characteristics and fines inhibitor evaluations by monitoring of dimensional changes. It is shown that there is no need to use glass in the form of fines since no swelling due to alkali–silica reaction is recorded when the diameter of the glass grains is less than 1 mm. Besides, fine glass powders having specific surface areas ranging from 180 to 540 m2/kg reduce the expansions of mortars subjected to alkali–silica reaction (especially when glass aggregates of diameters larger than 1 mm are used).