The Improvement of the Pozzolanic Properties of Recycled Glass during the Production of Blended Portland Cements

Abstract

The replacement of primary raw materials in cement production is a relevant topic today. One potentially usable raw material is recycled glass. The disadvantage of glass is its tendency towards aggregation. Due to this phenomenon fine glass incement composites work only physically and mechanically as filler rather than as an active pozzolan. The possibilities of improving the pozzolanic properties of recycled glass by means of new milling techniques were examined in this paper. Next to the pozzolanic activity of recycled glass, the advancement of the hydration process of the binder and the effect on the physical and mechanical properties were also monitored. A combination of a ball mill and a nontraditional high-speed pin mill DESI 11 was selected for sample preparation. Portland clinker and recycled glass mixed at a ratio of 80: 20wt. % were used for the preparation of the blended cement. The pozzolanic activity of the pure recycled glass was evaluated using a modified Chapelle test. The hydration process of glass grains in the cement composite was observed using an SEM with an EDX probe. The effect of the grinding technology on the cement rheology and on the compressive and flexural strength was also assessed. The results of the experiment show that the improvement of the pozzolanic properties of recycled glass by using it as the basis of blended cement is possible. The synergistic effect of the co-grinding of the components was observed. The glass particles were better distributed in the composite and could react with Portland cement hydration products. It positively influenced the values of the material's physical and mechanical parameters.