Utilization of glass shards from municipal solid waste in aluminium-based ultra-lightweight concrete

Abstract

• Glass powder react with portlandite and form an additional amount of low basicity CSH. • Glass powder increase dissolution of clinker mineral. • Glass shards from municipal solid waste can replace up to 30% of Portland cement. • Cleaned glass shards can be utilized in most types of concrete. • Glass shards without cleaning process can be utilized in aluminium-based ultra-lightweight concrete. The research proposed a method on how to prepare glass shards from municipal solid waste and utilize it in aluminium-based ultra-lightweight concrete (density ≤800 kg/m 3 ). In the research glass from municipal solid waste is prepared in two different ways: 1) washed under running water, dried, and milled in a ball mill (referred to as washed waste glass powder); 2) milled in a ball mill without washing (referred to as unwashed waste glass powder). In the research, Portland cement 42.5 R was used as the binder, aluminium powder was used as a foaming agent, β-calcium sulphate hemihydrate was used as early-strength agent, and sodium hydroxide was used as neutralizer of organic and other impurities. The aluminium powder showed good synergy with elemental aluminium found in unwashed waste glass powder. Sodium hydroxide also increases the dissolution of elemental aluminium. Additionally, polypropylene fibres were used to increase the integrity of hardened concrete structure. The main aim of the research is to utilize glass shards from municipal waste in ultra-lightweight concrete. The experiment was performed with and without CO 2 curing. The research revealed that it is possible to replace up to 30 % of Portland cement with waste glass powder without a decrease in compressive strength and to create ULWC with the density of ∼600 kg/m 3 , compressive strength of 3–6 MPa, and total porosity of ∼50 %–60 %. Experimental results confirmed that waste glass from municipal waste has pozzolanic and cementing properties, and therefore can replace some portion of Portland cement. The research is in line with the EU waste policy, which motivates extracting valuable resources from the dumpsite, converting them to beneficial raw materials, and thus reducing global CO 2 emissions. The proposed method is suitable to create ultra-lightweight concrete, which is a cheaper alternative for autoclaved aerated concrete.