高温后纳米改性水泥基材料的残余抗折强度
付 晔,李庆华,徐世烺

浙江大学建筑工程学院,杭州 310058

建筑材料; 残余抗折强度; 水泥基复合材料; 混杂纤维; 纳米改性; 微观结构

The effects of high temperature on flexural strengths of high performance nano-modified cementitious composites
Fu Ye, Li Qinghua, and Xu Shilang

Fu Ye, Li Qinghua, and Xu ShilangCollege of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, P.R.China

building materials; flexural strength; cementitious composites; hybrid fiber; nano-modified; microstructure

DOI: 10.3724/SP.J.1249.2014.02187

备注

对6种不同掺量钢纤维和PVA纤维组合的纳米改性水泥基材料(high performance nano-modified cementitious composites, HPNCC)高温后的抗折强度进行试验研究,探讨不同高温(200、400、600和800 ℃)对HPNCC抗折强度、质量损失和微观结构的影响,寻求试验范围内钢纤维与PVA纤维的最佳掺量组合.研究结果表明,经历200 ℃高温1 h后,HPNCC质量损失平均为3.90%,抗折强度略有降低,微观结构没有明显变化; 经历400 ℃高温1 h后,由于HPNCC质量损失大幅增加(平均为15.60%)及内部的PVA纤维融化、毛细孔水分蒸发、孔洞扩张和水泥基基体劣化,其抗折强度急剧下降; 经历600 ℃高温1 h后,HPNCC质量损失减缓,平均为16.89%,PVA纤维完全融化、挥发,抗折强度下降明显; 经历 800 ℃ 高温1 h后,微观结构进一步劣化,最优配比HPNCC的抗折强度保留36.52%.

The influence of micro polyvinyl alcohol(PVA)fibers and steel fibers on fire resistance, microstructures and mass loss of high performance nano-modified cementitious composite(HPNCC)is discussed. Specimens containing two different contents of PVA fibers and three different contents of steel fibers are examined. The specimens are exposed to a series of temperatures(200, 400, 600 and 800 ℃). The fire resistance of mixtures are quantified in terms of the residual mechanical properties(flexural strengths, deflection and stiffness)and mass loss. The microstructure characterization after exposure to fire is examined by scanning electron microscopy. Results indicate that after HPNCC is exposed to 200 ℃ for an hour, average mass loss of HPNCC is 3.90% while there is little change in flexural strength; after 400℃ exposure for an hour, average mass loss of HPNCC sharply reaches 15.60% and flexural strength drops obviously for melting of PVA fibers and degradation of cement matrix; after HPNCC is exposed to 800℃ for an hour, the optimal composition of HPNCC reserve is up to 36.52% of flexural strength.

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