自密实高性能混凝土高温爆裂性能试验研究.docVIP

 自密实高性能混凝土高温爆裂性能试验 研究 柳献，陶津，袁勇* 5 10 15 20 25 30 35 40 45 （同济大学土木工程学院，上海 200092） 摘要：自密实高性能混凝土的工程应用给研究者提出了新的问题，其在高温条件下的爆裂现 象近年来受到广泛的关注和研究。影响高性能混凝土高温爆裂的因素有两类，一类是组成材 料内部因素，如孔隙率、渗透性等；另一类是结构外部因素，如结构荷载条件与边界条件、 升温速率等，目前已有研究结果尚有不一致和争议之处，对自密实混凝土高温爆裂影响因素 的研究仍需要深入和细化。本文对自密实混凝土、掺加聚丙烯纤维的自密实混凝土与高强混 凝土进行了高温爆裂试验，对不同升温速率、不同聚丙烯纤维掺量、不同应力水平进行了综 合研究。为了解聚丙烯纤维在自密实混凝土高温爆裂中的作用机制，本文通过环境扫描电镜 对材料的微观性能进行了测试。通过分析不同升温机制、初始应力和纤维掺量等对混凝土爆 裂性能的影响，建立了自密实混凝土高温爆裂性能与微观组成结构之间的联系，揭示了不同 影响因素对自密实混凝土高温爆裂性能产生影响的原因。试验结果表明初始应力是影响自密 实混凝土爆裂的重要因素，且一定掺量的聚丙烯纤维对抑制自密实混凝土高温爆裂具有显著 的作用，最后探讨了聚丙烯纤维作用机理，提出了自密实混凝土高温爆裂抑制措施，对于自 密实混凝土的大规模推广和应用具有重要实际意义。 关键词：自密实高性能混凝土；高温爆裂；初始应力；聚丙烯纤维 中图分类号：TU50 The Explosive Spalling Reseach at High Temperature of High Performance and Self-compacting Concrete Liu Xian, Tao Jin, Yuan Yong (College of Civil Engineering, Tongji University, ShangHai 200092) Abstract: New questions come out during the practice of high performance concrete such as self-compacting concrete. Explosive spalling has been attracting these years. There are two factors influencing on the explosive spalling at high temperature, one is inner factors, such as property and permeability, the other is exterior factors, such as load and heating rate. There are different and opposite conclusions about the spalling of SCC. It is necessary to research the spalling factors of self-compacting concrete at high temperature.Experiments were performed on several kinds of high performance concrete, that is high strength concrete and self compacting concrete with different polypropylene fibers dosage in this paper. Different heating rates, stress levels and polypropylene fiber contents were studied based on the test results. After some special heating process, scanning electron microscopy was applied to investigate the microstructure. Based on the results, the relation between spalling and microstructure of concrete was studied. The results of test showed that a certain amount of polypropylene fiber could minimize the risk of spalling for