POTENTIAL USE OF GLASS WASTE POWDER AS A CEMENT REPLACEMENT IN CEMENT-BASED MORTAR

In Indonesia, glass is the 7^th largest waste contributor with difficult-to-decompose properties. In 2021, glass waste reached more than nine million tons and it is predicted to increase as it is becoming more popular every year. The major chemical composition of glass is silica and when the glass is milled down to smaller size particles (i.e., micro-size), it is expected to react with cement hydrates and promote the pozzolanic reaction to form secondary C-S-H. The use of glass waste as a substitute for cement as supplementary cementitious materials (SCM) is an important step that can lead to the production of more sustainable and energy-efficient cement-based construction. This research focused on investigating the effect of using glass waste powder consisting of clear, green, and brown colors as cement replacement in cementbased mortar. Physical and chemical properties of raw material (including X-ray fluorescence, scanning electron microscope, loss on ignition, and particle size analysis) are evaluated before the glass waste is cast into mortar. The mixture proportion of cement and glass powder is calculated based on ASTM C-311, which is 80% and 20% by weight, respectively. In this study, the cement-glass powder-based mortars are fabricated by casting into cube molds of 50x50x50 mm. According to the results of the compressive strength on the 56^th day, brown and clear glass powder had values of 23,62 MPa and 23,15 MPa, respectively. It indicated that a 20% cement replacement with clear and brown glass powder had the potential to be used as SCM.