Foam glass from municipal waste as a lightweight aggregate for cement mortar

Municipal waste glass has long been a problem because of its difficulty in disposal. In Chiang-rai province alone, it was approximated that improperly treated glass waste amounts to 20,000 kg per annum. Foam glass is a porous insulating material which provides the advantage of low-thermal conductivity, low density and fire resistance. This research aimed to prepare foam insulating glass using waste glass collected from local municipality. The glass was first cleaned and then crushed using a hammer mill. Further grinding using ball milling technique was done until glass powder was obtained. With the use of proper amounts of foaming agent, calcium carbonate (CaCO₃), and binder, cassava gel, glass foams could be prepared at the temperature of 750 °C. Microstructure was observed using an optical microscope, while density was measured using water replacement. The obtained foam glass has a bulk density of 0.535 g/cm³ with approximated porosity of 77%. To observe ability as a lightweight aggregate, cement mortar with different amounts of glass foams was prepared. It was found that thermal conductivity linearly decreased while compressive strength increased when the amount of the foamed glass was increased. Compressive strength and thermal conductivity of the foam glass were estimated to be 2.43 MPa, of 0.23 W/m.K, making it a new economically promising lightweight aggregate for cement mortar.