Potential use of spherical glass sourced from cathode ray tube funnel glass for the application as coarse aggregate in concrete

Abstract

Managing discarded waste cathode ray tube (CRT) funnels glass has become a major concern worldwide because it has toxic effects on the environment and human health if the hazardous lead leached to the surroundings. The common way of recycling this waste is by crushing it, where it was used as an alternative fine aggregate for concrete production. But the crushing technique has led to the formation of micro-cracks in the funnel glass products, causing to high lead leaching rate. On the other hand, recycling the CRT funnel glass waste through melting and annealing operations in producing the spherical CRT glass (GS) has proven will not danger the environment due to the leaching of lead. Therefore, this paper explored the feasibility of using GS as partial (20%, 50%) and full replacements (100%) of natural coarse aggregates in concrete. The workability, density, compressive strength, and splitting tensile strength were investigated. Given the importance of materials and exposure, the influence of silica fume content and CRT concrete strength subjected to high temperature were evaluated. Overall, the inclusion of GS increased the workability and decreased the density, but reduced the compressive and tensile strength. The use of GS as coarse aggregates should be limited to below 50% due to its negative impacts on the strength aspects have become obvious. However, the results show that the CRT concrete made with 20% GS and 10% silica fume have comparable properties with the control, 52 MPa where only 7% lower than control concrete. The addition of silica fume able to counteract the negative effect of GS.