Valorization of hazardous glass wastes via geopolymer production utilized in gamma ray shielding applications: A comparative study with Portland cement

Abstract

The main goal of this study is to fabricate low cost green binding material produced from the safe recycling of soda-lime glass waste (SLG), hazardous lead-rich glass waste (LRG) and slag (GGBFS). A comparative study was performed between OPC paste and five geopolymer pastes; alkali-activated slag (AAS), AAS-30%SLG, AAS-25%SLG-5%LRG, AAS-20%SLG-10%LRG and AAS-15%SLG-15%LRG. Low concentration of NaOH solution was used to fabricate geopolymer pastes. OPC paste has been cured under tap water while geopolymer pastes treated under high humidity up to 28 days. The compressive strength for six hardened pastes was measured at different curing times (1, 3, 14 and 28 days). Moreover, chemically combined water %, bulk density, total porosity % and water absorption % were measured at 28 days of curing. Linear attenuation coefficient (μ), half-value layer (HVL), mean free path (MFP), and transmission fraction (TF) were also determined as gamma ray attenuation parameters. Various techniques have been utilized to identify the formed hydrates/gels such as XRD, TGA/DTGA and SEM/EDX. It was found that, the geopolymer pastes, prepared at room temperature, have lower compression strength than the corresponding OPC pastes at all ages of curing. However; they have acceptable attenuation capacity, as compared with OPC, at different intensities of gamma rays (0.66, 1.17 and 1.33 MeV). It was found that, the linear attenuation coefficients of AAS and AAS-20%SLG-10% LRG hardened pastes increased by 10.7 and 9.6%, respectively than the corresponding value of OPC paste at 0.66 MeV. To achieve the same mechanical efficacy, all geopolymer pastes after 28-day of curing were thermally activated by heating up to 250 °C. From economic and environmental points of view, the production of these geopolymers minimized the energy consumption and CO2 emissions by 60 and 90%, respectively as compared with OPC.