Production of Autoclaved Cementitious Composites Using Recycled Waste Glass

Abstract

One of the major negative environmental implications of economic growth and the advancement of information technology is the large quantity of electronic waste dumped in landfills. Cathode ray tubes (CRTs) from outdated televisions and computer monitors are a significant source of electrical waste. The CRT funnel primarily consists of silica, significant alkalis (Na<inf>2</inf>O-K<inf>2</inf>O), and heavy metals like barium-strontium, along with a substantial lead (Pb) content that may contaminate the soil. Owing to its heavy metal content, CRT is considered hazardous waste, and regulations require its glass to be recycled or repurposed instead of landfill disposal. The low pozzolanic activity of CRT silica suggests that its high content, when paired with an optimized particle size and specific curing conditions, can enhance the mechanical properties of cement-based products. Hydrothermal treatment has been found to speed up both the hydration of ordinary Portland cement (OPC) and the pozzolanic reactions. Since the main objective was to safely recycle large amounts of CRT, three mixes were proposed with 10%, 20%, and 30% OPC + 90%, 80%, and 70% CRT, respectively, and the effect of hydrothermal curing conditions on mechanical properties and durability of these blends was investigated. CRT-70, a blend containing 70% CRT glass waste, showed enhanced strength due to the formation of zeolitic phases and calcium silicate hydrate (CSH). These phases also provided CRT-70 with notable fire resistance, ensuring its structural stability under elevated temperatures. These results demonstrate the possibility of production of precast building products via high-volume recycling of hazardous CRT waste.