Assessment of the compressive strength of recycled waste LCD glass concrete using the ultrasonic pulse velocity

This study uses a fixed weight ratio of 7:2:1 of cement, fly ash and slag powder as binder material and uses waste liquid crystal display (LCD) glass sand through a No. 4 sieve to replace 0%, 10%, 20% and 30% of the fine aggregate using the volumetric method, combined with water-binder ratios (w/b) of 0.28, 0.32 and 0.36 for a series of tests to determine the compressive strength and ultrasonic pulse velocity (UPV) of self-consolidating glass concrete (SCGC). The test results show that the compressive strength and UPV increase with age but decrease as the water-binder ratio increases. The compressive strength and UPV present a nonlinearly increasing relation curve, the water-binder ratio influences the curve insignificantly, and there is a right shift as the waste glass replacement increases. Therefore, the UPV of SCGC increases with the waste glass replacement G value, but the compressive strength decreases as the G value increases. In addition, this study uses the exponential function as a basis, combined with the compressive strength and UPV characteristics of waste LCD glass concrete; by considering the w/b, waste glass replacement G and UPV variables, the compressive strength prediction model is deduced. The analysis results show that the mean absolute percentage error (MAPE) value for the compressive strength test result and the assay value of SCGC is 6.45-7.97%; compared with the MAPE value, which is 8.61-12.51%, as obtained by linear function regression, the analysis result accuracy is increased by 25.1-36.3%. In the same way, the MAPE value of the WGCLSM (waste glass controlled low strength material) is 8.15-11.24%; compared with the MAPE value, which is 21.33-26.19%, as obtained by linear function regression, the accuracy is increased by 51.2-62.2%. Furthermore, the MAPE value obtained by a compressive strength prediction analysis of HPGC (high-performance recycled liquid crystal glass concrete) is 7.18-8.65%. Therefore, this study builds an analytical model that uses UPV to evaluate the compressive strength; its forecast accuracy is good, and it is applicable to waste LCD glass concrete for different functional requirements. It is very helpful for the safety assessment analysis of concrete structures with similar mix proportions and nondestructive testing UPV.