دانلود رایگان مقاله انگلیسی خواص حرارتی بتن RCA زبر در دمای بالا - الزویر 2018

Abstract

An experimental investigation was carried out on the thermal properties of concrete made with coarse recycled concrete aggregate (RCA) in the temperature range from room temperature to 800 °C. Three different concrete mixtures were produced with replacement percentages of 0%, 50% and 100% coarse RCA. The thermal properties at elevated temperatures, including thermal conductivity, specific heat and thermal expansion were obtained from the tests. Test results in this paper show that the thermal conductivity of coarse RCA concrete decreases with increasing coarse RCA content. The development trends of thermal conductivity and specific heat with temperature are similar among concretes with different coarse RCA content. For thermal expansion, the concrete with 50% coarse RCA has a larger value than the concrete containing 0% and 100% coarse RCA at temperatures above 500 °C. Based on the test data, simplified equations were proposed to express the elevated-temperature thermal properties of coarse RCA concrete.

4. Conclusions

This study investigated the thermal properties (thermal conductivity, specific heat and thermal expansion) of coarse RCA concrete for temperatures up to 800 °C. The following conclusions were drawn from the results of this study:

The thermal conductivity of coarse RCA concrete at room temperature and elevated temperatures decreases with the increase of coarse RCA replacement percentage. As the specimen’s temperature is increased, the thermal conductivity of coarse RCA concrete decreases.

There are two major peaks of specific heat for coarse RCA concrete in 25-800 °C range. The coarse RCA content has no regular influence on the specific heat of concrete at elevated temperatures.

The thermal expansion of coarse RCA concrete increases with temperatures from 20 to 800 °C. Above 500 °C, concrete at 50% replacement has a larger thermal expansion than 0% and 100% coarse RCA concrete.

The suggested relationships to model the elevated-temperature thermal properties of coarse RCA concrete can be used to evaluate the behavior of structures made with coarse RCA concrete under fire exposure.