Effects of Glass Fiber,Air Entraining Agent and Lightweight Aggregate on Thermal Conductivity of High Performance Concrete

• Main Authors: Lo Zang Wen, 羅贈文
• Other Authors: Shun Tyan Chen
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/25989261492395608001

碩士 === 國立臺灣科技大學 === 營建工程技術學系 === 86 === High Performance Concrete (HPC) is a new construction material with high strength and high slump flow. However owing to its higher density, it also possesses higher thermal conductivity and is even easier to spall in fire temperature than ordinary concrete. In order to promote its engineering application, these negative fire -resistance characters need to be improved. This research tries to mix respectively the lightweight aggregate, fiber glass and air entraining agent in HPC and studies the effect of improvement of these mixtures on the fire-resistance behavior of HPC. The research project is divided into two parts : the first part studies the effect of the mixtures on the spalling and thermal expansion behavior of HPC； while the second part deals with the effect of the mixtures on the thermal conductivity and volumetric heat capacity of HPC. This report presents the research outcome of the second part. The parameters considered in this study are the strength of concrete , the amount of the lightweight aggregate, fiber glass and air entraining agent. A number of 30cm×30cm×10cm HPC specimens have been made and tested under an one-dimensional heat load. The temperature rate was set to be 5℃/min in the tests and the maximum temperature was 1000℃. Using the temperature data measured from the thermal couples installed in the testing specimens to gather with the derived difference equation for heat conduction, the thermal conductivity and the volumetric heat capacity of HPC are than determined . It is indicated from this study that concrete with higher fc'' has also higher thermal conductivity. Reducing the amount of the above-mentioned mixtures in HPC will reduce its thermal conductivity and increase its volumetric heat capacity as well. This research also conducts a nonlinear heat conduction finite element analysis using the obtained thermal conductivity and the volumetric heat capacity as input material properties. The temperature distributions resulted from the analysis agrees very well with the measured ones. This indicates that the method developed to measure the thermal conductivity and volumetric heat capacity in this study is quite reliable .