A study of the effects of LCD glass sand on the properties of concrete

In order to study the recycling of discarded liquid crystal display (LCD) glass into concrete (LCDGC), a portion of the usual river sand was replaced by sand prepared from discarded LCD glass. Three different mix designs were regulated by the ACI method (fc28 = 21, 28, and 35 MPa) with 0%, 20%, 40%, 60%, and 80% LCD glass sand replacements investigated; their engineering properties were determined. Test results revealed that, when compared to the design slump of 15 cm, the 20% glass sand concrete for the three different mix designs kept good slump and slump flow. Furthermore, a slump loss ranging from 7 to 11 cm was observed for specimens with 60% and 80% glass sand replacement for the design strengths of 28 and 35 MPa. The compressive strengths of the concrete with glass sand replacement were higher than the design strengths. Moreover, the durability of the concrete with 20% glass sand replacement was better than that of the control group. Surface resistivity for specimens with different amounts of LCD glass sand replacement was also higher than that in the control group for mid to long curing ages. The sulfate attack in concrete with different amounts of glass sand replacement caused less weight loss than in the control group. Moderate chloride ion penetration was observed for glass sand concrete. Furthermore, the measured ultrasonic pulse velocities for LCD glass sand concrete specimens were higher than 4100 m/s, which qualified these specimens as good concrete. OM and SEM indicate that the dense C–S–H gel hydrate was produced at the interface between the glass sand and cement paste. The test results indicate that the addition of 20% LCD glass sand to concrete satisfies the slump requirements and improves the strength and durability of concrete. This suggests that LCD glass sand can potentially be used as a recycled material in concrete applications.