The Use of Ground Glass as a Pozzolan

Abstract

The paper presents data on the durability of concrete produced using ground glass as a pozzolan. Various sources of glass were used including soda glass, e-glass and Pyrex glass. All the materials showed excellent pozzolanic activity when ground to pass 75-microns. The use of ground glass resulted in substantial reductions in permeability and chloride penetrability, and improved resistance to sulfate attack. Air-entrained concrete containing glass showed good freeze-thaw resistance. E-glass and borosilicate glass were effective in preventing deleterious expansion due to alkali-silica reaction (ASR). Bottle glass, which contains substantial amounts of alkali, was not efficacious with regards to ASR. The inclusion of bottle glass results in very substantial increases to the pore solution alkalinity and this can result in substantial increases in expansion in concrete containing reactive aggregate and low-alkali cement. It is shown that the accelerated mortar bar test is not suitable for evaluating the impact of high-alkali materials on ASR as the alkalis contributed by the cementing materials are released when the mortar bars are masked by the conditions of the test (first immersed in hot water and then in hot NaOH solution).