Effect of new mixing method of glass powder as cement replacement on mechanical behavior of concrete

Abstract

This study investigates the effects of using local wastes of Glass Powder (produced from crushing the glass waste) as replacement of cement in fresh and hardened concrete. Four percentages of Glass Powder (GP) were used: 0%, 10%, 20%, and 30%. Two mixing methods were used in the study. First, the conventional mixing method, where the glass powder was added with the cement and aggregates. Second, the glass powder was dissolved in water before adding it to cement and aggregates. The slump increased as the glass powder replacement increased in the concrete due to the presence of more free water in the structure, which leaded to have lower density and higher water absorption. As a result, the compressive strength of conventional mixes method decreased as the glass powder increased at early age. Later, after 90 days, the highest compressive strength was obtained for the 20% GP. The new mixing method showed higher compressive strength than the conventional mixing method. Using 10% GP in the new mixing method gave a significant increase, around 130% of the compressive strength of the control mix. This increase can be related to the hydrolysis of the glass powder into free ions of SiO2, CaO and Na2O in the water which formed more CSH. The relative index proves the rise of the glass powder reactivity as the amount of glass powder increases.