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BULLETIN OF THE CHINESE CERAMIC SOCIETY ›› 2024, Vol. 43 ›› Issue (3): 956-964.

Special Issue: 资源综合利用

• Solid Waste and Eco-Materials • Previous Articles     Next Articles

Effects of Mineral Admixtures on Frost Resistance and Renewability of Recycled Aggregate Concrete

CHENG Xu, ZHU Pinghua, WANG Xinjie, LIU Hui, WANG Huayu, WANG Yueying, CHEN Chuirui   

  1. School of Urban Construction, Changzhou University, Changzhou 213164, China
  • Received:2023-11-10 Revised:2023-12-12 Online:2024-03-15 Published:2024-03-27

Abstract: In order to explore the effects of mineral admixtures on frost resistance and renewability of recycled concrete, three kinds of mineral admixtures, such as silica fume fly ash, fly ash silica fume and granulated blast furnace slag, were selected. Five groups of recycled aggregate concrete with different cementitious systems were prepared by different dosage combinations. The freeze-thaw test of recycled aggregate concrete was carried out by rapid freezing method. By measuring the relative dynamic elastic modulus, mass loss rate and compressive strength loss rate of recycled aggregate concrete during the freeze-thaw process, the frost resistance of recycled aggregate concrete with different cementitious systems was evaluated. The microstructure of recycled aggregate concrete after freeze-thaw cycle was observed by SEM. In addition, the recycled aggregate concrete after freeze-thaw cycle was crushed to obtain the second generation of recycled coarse aggregate, and the renewability of recycled aggregate concrete was evaluated according to its apparent density, crushing value, firmness value and water absorption. The results show that the mass loss rate and compressive strength loss rate of combination of 5% (mass fraction, the same below)silica fume +20% fly ash +20% slag +55% cement are significantly lower than those of combination of 5% silica fume, 5% silica fume +20% fly ash and 5% silica fume +20% slag, and the relative dynamic elastic modulus is also higher than that of other combinations. The second generation of recycled coarse aggregates of four combinations all meet the grade Ⅲ aggregate standard, which can be reused for structural concrete with strength grade of C25.

Key words: recycled aggregate concrete, recycled coarse aggregate, mineral admixture, frost resistance, renewability

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