Engineering Properties and Leaching of Heavy Metals on Self-leveling Mortars Mixed with Waste Printed Circuit Boards as Fine Aggregate Replacement
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Abstract
Currently, end-of-life electrical and electronic equipment is the fastest-growing environmental waste problem, with Waste Printed Circuit Boards (WPCBs) being especially difficult to dispose of. As a result, the non-metallic parts of WPCBs were used as physical process recycling waste in the production of self-leveling mortars in this study. WPCBs were used as a fine aggregate replacement in mortars in a mixed proportion of 2.5–20% by weight. WPCB physical properties, mortar fresh and hardened properties, insulating mortar properties, X-ray analysis, and heavy metal leaching were investigated. Results showed that WPCB's grading characteristics were close to those of fine aggregates, while their specific gravity and density were lower than those of fine aggregates. Self-leveling mortars tended to increase water demand and setting time as the percentage replacement of fine aggregates increased, while density and compressive strength tended to decrease. Self-leveling mortars had better insulating properties. As for heavy metal leaching, the amount of heavy metal mixed in the electronic circuit board was within the specified standard. To consider the use of leveling mortars, the optimum amount for mixing WPCBs should not exceed 15% for underlayment or 7.5% for overlayment work.
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