Papers by Author: Chao Wei Tang

Abstract: This paper reports the application of Taguchi optimization technique in determining process condition for synthetic lightweight aggregates by incorporating waste liquid crystal displays (LCD) glass with reservoir sediments. In the study the waste LCD glass cullet was used as an additive. It was incorporated with reservoir sediments to produce lightweight aggregates. Taguchi method with an L₁₆(4⁵) orthogonal array and five controllable 4-level factors (i.e., cullet content, preheat temperature, preheat time, sintering temperature, and sintering time) was adopted. Then, in order to optimize the selected parameters, the analysis of variance method was used to explore the effects of the experimental factors on the performances (particle density and water absorption) of the produced lightweight aggregates. The results showed that it is possible to produce high performance lightweight aggregates by incorporating waste LCD glass cullet with reservoir sediments.

Abstract: Structural lightweight aggregate concrete (LWAC) members have demonstrated greater fire endurance periods than equivalent thickness members made with normal-weight aggregates. Superior performance is due to a combination of lower thermal conductivity, lower coefficient of thermal expansion, and the inherent thermal stability developed by aggregates that have been exposed temperature greater than 1050°C during preprocessing. Furthermore, LWAC exhibits relatively high thermal insulating value, of which the thermal conductivity can be half as much as that of ordinary normal-weight concrete (NWC). Therefore, the main objective of this paper is to implement fire resistance testing for structural and non-structural elements made of LWAC and NWC to assess and compare their fire behavior.

Abstract: In the paper the properties of concrete masonry unit (CMU) made from sedimentary lightweight aggregate (LWA) were investigated. The main variables include water to cementitious material ratio (W/CM), filling ratio of paste or mortar in voids between coarse aggregate particles (Fv), filling ratio of sand in mortar (Fm), and cement replacement level by slag (Sc). Test results of representative CMU specimens show that unit weight ranged from 1585 to 1743 kg/m3, which was 30-25% lower than that for a normal weight CMU (2300 kg/m3); compressive strengths ranged from 8.4 to 18.7 MPa; water absorption was found to vary between 0.05 to 0.13 g/cm3; and thermal conductivity ranged from 0.27 to 0.41 W/mK. The research findings demonstrate that the use of sedimentary LWA as coarse aggregate in various concrete mixtures could produce high performance lightweight CMU, which comply with the requirements of Chinese National Standards (CNS) standards.

Abstract: The present study experimentally investigated the pre-failure and post-fatigue behavior of reinforced concrete (RC) beams constructed with lightweight aggregate concrete (LWAC) in comparison with that constructed of normal weight concrete (NWC) of the same compressive strength (40 MPa). A total of twelve RC beams were tested under different fatigue loadings. Based on the experimental observations, the midspan total deflection measured in the fatigue testing consisted of the elastic and plastic components. The mechanismof the two deflection components developed with load cycles was different. The experimental results showed that the fatigue resistance of LWAC beams was better than that of NWC beams for the same fatigue loading levels. It was reflected in both the lower evolution of fatigue damage and the smaller growth of midspan residual deflection. After 2 million cycles, an average increase in residual load capacity of about 8% was found in the NWC beams, while that in the LWA beams remained virtually unchanged.