About the author:

Shenzhen Construction Engineering Group Co., Ltd., Shenzhen, Guangdong 518000,China

Abstract:

To improve the performance of recycled aggregates in high⁃strength concrete, this paperinvestigates the effects of two modification methods （ cement paste treatment and geopolymer pastetreatment） on the properties of recycled aggregates, as well as the macroscopic performance andmicrostructural changes of modified recycled aggregates in high⁃strength concrete. Through testing ofworkability, mechanical properties, pore structure, and microstructure, the enhancement effect of differentmodification methods on the performance of recycled aggregate⁃based high⁃strength concrete was explored.The results show that both cement paste and geopolymer paste modifications significantly improve theinterface bonding between aggregates and cement matrix,with geopolymer paste treatment exhibiting a morepronounced effect. The silica⁃aluminate gel formed by geopolymer modification creates a dense gelstructure, further enhancing the microstructural compactness and mechanical properties of concrete. When100% of natural aggregates are replaced, the geopolymer⁃modified recycled aggregate concrete exhibits aslump of 220mm, compressive strength of 95MPa, and permeable porosity lower than 15%.