Potential reuse of recovered nonmetallic printed circuit board waste as sand replacement in construction materials

Abstract

The study analyzed the treatment of nonmetallic printed circuit board (PCBs) by adding them into mortar cement and cement brick as sand replacement. This study aims to propose methods for reuse of nonmetallic PCBs waste. The leachability of raw nonmetallic PCBs was tested by performing crushed block leachability test (CBL). This test was conducted to determine the suitability of nonmetallic PCBs as a nontoxic material in terms of environmental. Mortar cement and cement brick specimens with nonmetallic PCBs ranging from 0% to 40% and 0% to 50% by weight of sand were prepared. The effectiveness of the treatment was evaluated by performing compressive strength as well as flexural strength, water absorption and whole block leaching (WBL) tests on the treated nonmetallic printed circuit board. The durability of mortar added 10% nonmetallic PCBs waste was also examined through acidic conditioning tests. The results indicated that the leaching of selected heavy metal ions from the cement matrix and raw nonmetallic PCBs are within the standard limits set by Department of Environment Malaysia (DOE). The analysis from TCLP test showed that almost all of concentration of metal ions detected in the CBL test (without treatment) was higher than the concentration of ion in WBL test (treatment). The compressive strength and flexural strength of the mortar added with nonmetallic PCBs was generally lower in the range of 10.1 N/mm2 to 31.9 N/mm2 for compressive strength and 3.5 N/mm2 to 7.7 N/mm2 for flexural strength than the control samples which is 33.5 N/mm2 and 8.0 N/mm2. The amount of nonmetallic PCBs to replace sand for optimum strength of mortar was about 28% with 95% confident level of ANOVA, and for brick the optimum proportion of nonmetallic PCBs is not more than 30%. From durability tests, weight and compressive strength both of mortars was decrease after soaking in acid solution. The total weight and compressive strength change is about 1.11% and 11.11% for mortar added with nonmetallic PCBs while 0.94% and 13.29% for control mortar. As a conclusion, the study shows that nonmetallic PCBs can be reused in profitable and environmentally friendly ways and has broad application prospects.