Study of mechanical and microscopic properties using hybridized waste glass and manufactured sand in cement mortar

Abstract

The production of waste glass in China was more than 20 million tonnes, but the current recycling rate was only around 30%. How to recycle this glass was a problem that urgently needed to be solved. This study used green glass and TFT-LCD glass to replace manufactured sand in 20%, 40%, 60% and 80%. Different proportions of mixed sand were composed to prepare cement-based specimens to investigate the effect of varying waste glass on the strength and pore structure of the cement-based materials through the mechanical test, porosity and water absorption test, resistivity test, mercury intrusion porosimetry. Finally, the hydration products generated in the interfacial transition zone were observed through scanning electron microscopy (SEM) to explain the mechanism of the action of waste glass on cement-based materials containing manufactured sands. The test results showed that adding the two types of glass sands reduced the flowability of the cement-based materials while adversely affecting the flexural strength of the cement-based materials. The compressive strength reached the optimum at 20% substitution, higher than the compressive strength of river sand and manufactured sand groups. From the SEM observations, the specimen mixed with 20% glass sand generated more types of hydration products than the manufactured sand group at three days and optimized the pore structures. At 28 days, the compressive strength of GG20 specimens was 8% higher than that of the RS group. Therefore, the replacement amount of GG up to 20% had optimum admixture.