| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 97 === The aim of this study is to investigate the feasibility of using wasted tiles to substitute for part of the fine aggregates and crushed tile-powder to replace cement as recycled cement mortar (RCM). Experiment specimens were made with two water binder ratios and several replacement levels of recycled aggregates. Compressive strength, ultrasonic pulse velocity (UPV), loss of ignition (LOI) and x-ray diffraction (XRD) analysis of mortars are carried out in this study. Properties of recycled mortar with waste ties subjected to elevated temperatures exposure are also discussed in the thesis.
Experiment result showed that the mortar with 25% recycled fine aggregate has the best performance in compressive strength with low water binder ratio and the mortars with 25% and 50% replacement approach the strength compared to the control group with high water binder ratio. The RCM with 20% and 10% recycled powder approach the strength of the control group. Mortar with more compressive strength has the faster UPV, more compact density and larger loss of ignition. The observation of XRD analysis showed that Pozzolanic reaction happened when the recycled cement mortar replaced waste tiles after 28 days. Due to the hydration of cement paste was still active at early time, exposure to high temperature will enhance hydration of recycled cement paste, resulting in increase in compressive strength in the order of 20-31%. On the long term effect, strength increasing in the order of 8-20% result from the curing hydration had reacted more completely. Reduction in compressive strength occurs shortly as recycled concretes subjected to elevated temperature below 440℃, and there is a notable reduction in strength when the elevated temperature is about 580℃-800℃. Experiment results also observed that the UPV is decreased due to cracks caused by high temperature effect. The development of LOI is decreased when exposure temperature is increased.
|
|---|
