Study on lightweight aggregate from TFT-LCD waste glass and Basic Oxygen Furnace Slag for concrete
Date Issued
2014
Date
2014
Author(s)
Chen, Kuan-Chun
Abstract
In present study, lightweight aggregate (LWA) was produced by a mixture of thin-film transistor liquid-crystal display (TFT-LCD) waste glass, basic oxygen furnace (BOF) slag using a rotary kiln. The resulted lightweight aggregate was used to prepare lightweight concrete in different water to cement ratios. Compressive strength analyses at different curing ages were carried out to study the effects of W/C on compressive strength. In addition, to understand transformation of stress distribution in the lightweight concrete under compressive strength test at different curing ages, a linear regression analysis was performed to find out dividing strength. Finally, interaction between mortar and aggregate and its effect on compressive strength of concrete were identified by observing the interfacial transition zone (ITZ) of the microstructure.
The results indicate that compressive strength of the lightweight concrete were 26.95 MPa (W/C=0.7)、43.78 MPa (W/C=0.5) and 49.89 MPa (W/C=0.3) at 28 days. When the w/c ratio was 0.3, lightweight concrete reaches its ceiling strength which was 50 MPa. The strength of lightweight concrete depended on the structure of ITZ at a high W/C and early curing age. But the lightweight concrete strength may turn to depends on coarse aggregate strength because the strength of mortar and ITZ can increases with increasing curing ages and reducing W/C.
Concrete density primarily depended on the aggregate density. All of the investigated lightweight concrete densities in present work were below 1800 kg/m3. Both density and compressive strength met ASTM C330 (standard specification for lightweight aggregate for structural concrete). The dividing strength of the lightweight concrete is 48.79 MPa. According to the concept of dividing strength, the designed compressive strength of concrete should be smaller than its dividing strength. It ensures that the use of amounts of cement would be more economic. Structural efficiency factor of the lightweight concrete was higher than the normal weight concrete even though the w/c ratio was low.
According to above discussions, lightweight aggregate which was made of TFT-LCD waste glass and basic oxygen slag has good mechanical behavior. The good compressive strength of lightweight concrete gave it potential for application in structural lightweight aggregate. It would be a good structural lightweight aggregate when designed concrete strength was below 50 MPa.
Subjects
人造輕質骨材
輕質混凝土
結構效率因子
分界強度
界面過渡區
Type
thesis
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