Use of CRT funnel glass in concrete blocks prepared with different aggregate-to-cement ratios

Managing huge quantities of cathode ray tube (CRT) glass waste has attracted much research interest since the last decade. A recycling process has been developed by The Hong Kong Polytechnic University, to turn hazardous CRT waste glass into valuable resources (e.g. treated funnel glass (TFG)). However, finding a beneficial use for the recycled TFG remains an issue for the local waste management industry. In this study, the use of TFG to replace recycled fine concrete aggregates in concrete blocks prepared with different aggregate-to-cement (A/C) ratios was investigated. The experimental results show that the impermeable nature of TFG made concrete blocks more resistant to water penetration and have lower drying shrinkage. The use of TFG also increased the block density and improved the X-ray radiation–shielding performance. All the blocks demonstrated acceptable compressive strength and alkali-silica reaction behaviour, and a lower A/C ratio could maintain a better alkaline environment and stronger cement matrix structure to stabilize and solidify the TFG in the blocks to prevent lead leaching. On the basis of the findings, the authors concluded that it is feasible to utilize high per cent of TFG in concrete blocks if a proper A/C ratio and appropriate casting method are used.