共聚甲醛纤维超高性能混凝土高温后残余力学性能

研究了掺入6、8、12 mm共聚甲醛纤维及钢纤维的超高性能混凝土(UHPC)高温后残余力学性能及微观结构。结果表明: 400 ℃时, 仅素混凝土发生爆裂; 500 ℃时单掺钢纤维UHPC试件发生爆裂, 单掺共聚甲醛纤维及混掺2种纤维的UHPC试件仍能保持相对完整, 后者高温残余强度较高。UHPC中共聚甲醛纤维在高温蒸汽养护后, 能与基体紧密黏接, 165 ℃后纤维熔化形成的孔洞能有效缓解并释放蒸汽压, 保持混凝土基体完整, 防止其在500 ℃发生高温爆裂。本工作揭示了共聚甲醛纤维在混凝土高温性能方面的作用机理, 对其在UHPC中应用有参考价值。

Abstract

The residual mechanical properties and microstructure of UHPC mixed with 6, 8, 12 mm copolymer formaldehyde fiber and steel fiber after high temperature were studied. The test results show that at 400 ℃, only plain concrete bursts. At 500 ℃, the steel fiber UHPC specimen burst, while the UHPC specimen with single copolymer formaldehyde fiber and mixed with two kinds of fiber can still maintain relatively integrity, and the latter has higher residual strength at high temperature. SEM and pore structure show that the copolymer formaldehyde fiber in UHPC can be closely bonded to the matrix after steam curing at high temperature. The pore formed by fiber melting at 165 ℃ can effectively relieve and release steam pressure, keep the concrete matrix intact and prevent it from cracking at 500 ℃. The research results reveal the mechanism of the copolymer formaldehyde fiber on the high temperature performance of concrete, which has great reference value for its application in UHPC.

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何越骁, 黄维蓉, 郭江川, 陈行, 晏茂豪, 王娇. 共聚甲醛纤维超高性能混凝土高温后残余力学性能[J]. 硅酸盐学报, 2022, 50(3): 839. HE Yuexiao, HUANG Weirong, GUO Jiangchuan, CHEN Hang, YAN Maohao, WANG Jiao. Residual Mechanical Properties of Ultra-High Performance Concrete Doped with Copolymer Formaldehyde Fiber Exposed to High Temperature[J]. Journal of the Chinese Ceramic Society, 2022, 50(3): 839.

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