Recovery of mortar-aggregate interface of fire-damaged concrete after post-fire curing

Lang Li, Hong Zhang, Jiangfeng Dong, Hongen Zhang, Pu Jia, Qingyuan Wang and Yongjie Liu

Abstract

In order to investigate the strength recovery of fire-damaged concrete after post-fire curing, concrete specimens were heating at 2oC/min or 5oC/min to 400, 600 and 800oC, and these exposed specimens were soaked in the water for 24 hours and following by 29-day post-fire curing. The compressive strength and split tensile strength of the high-temperature-exposed specimens before and after post-fire curing were tested. The proportion of split aggregate in the split surfaces was analyzed to evaluate the mortar-aggregate interfacial strength. After the post-fire curing process, the split tensile strength of specimens exposed to all temperatures was recovered significantly, while the recovery of compressive strength was only obvious within the specimens exposed to 600oC. The tensile strength is more sensitive to the mortar-aggregate interfacial cracks, which caused that the split tensile strength decreased more after high-temperature exposure and recovery more after post-fire curing than the compressive strength. The mortar-aggregate interfacial strength also showed remarkable recovery after post-fire curing, and it contributed to the recovery of split tensile strength.

Key Words

concrete; high temperature; post-fire curing; mortar-aggregate interface, image analysis

Address

Lang Li: Failure Mechanics & Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, College of Architecture & Environment, Sichuan University, Chengdu 610065, China; Key Laboratory of Deep Underground Science and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China Hong Zhang: Key Laboratory of Deep Underground Science and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China Jiangfeng Dong: Failure Mechanics & Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, College of Architecture & Environment, Sichuan University, Chengdu 610065, China Hongen Zhang: Failure Mechanics & Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, College of Architecture & Environment, Sichuan University, Chengdu 610065, China Pu Jia: Institute for Disaster Management & Reconstruction, Sichuan University, Chengdu, 610065, China Qingyuan Wang: Failure Mechanics & Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, College of Architecture & Environment, Sichuan University, Chengdu 610065, China Yongjie Liu: Key Laboratory of Deep Underground Science and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China

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