摘要
为研究聚丙烯粗纤维对高强混凝土高温后性能的影响,测试了不同目标温度(200℃、400℃、600℃和800℃)后高强混凝土的残余抗折强度、基体质量损失率及吸水率,同时结合超声波无损检测技术,分析了不同受火温度后高强混凝土的内部损伤。结果表明:聚丙烯粗纤维的掺入对HSC高温后抗折强度存在不利影响,其中聚丙烯粗、细纤维混杂协同作用的影响最小,400℃时粗、细纤维体积分数均为0.1%的混杂纤维混凝土抗折强度为基准组的90%。与细纤维相比,聚丙烯粗纤维熔化后形成的泄压通道更为粗化,高温后基体质量损失率及吸水率更大;粗纤维掺量过高,泄压通道将过于粗化,总孔隙率明显增大,即聚丙烯粗纤维的使用存在最佳掺量。不同纤维掺量下HSC的损伤度随受火温度演化结果相一致,通过对实验结果的非线性拟合,建立了聚丙烯粗纤维高强混凝土损伤度随受火温度变化的数学模型,根据该模型,可以依据受火后混凝土损伤度的测试结果,计算其受火温度。
Through the experiments on the properties of specimens after being exposed to certain temperatures （200 ℃,400 ℃,600 ℃ and 800 ℃）, the flexural strength, matrix mass loss rate and water absorption rate of polypropylene （PP） macro-fiber reinforced high strength concrete were studied. Also the internal damage of concrete was analyzed by the ultrasonic non-destructive testing technology. The results show that PP macro-fiber has disadvantage effects on the flexural strength of HSC, while the synergistic reaction of the hybrid fibers （PP micro-fiber and PP macro-fiber） can make the effects to minimize. The flexural strength of HSC mixed with the hybrid fibers （ the volume fraction of any fibers was 0.1% ） is 90% of basic group. Compared with the micro-fiber, the pressure relief channels which formed by the melting of PP macro-fiber were more coarsening, meanwhile the matrix mass loss rate and water absorption rate of HSC mixed with PP macro-fiber are higher. But too high PP macro-fiber dosage, the pressure relief channels will be too coarse, and the total porosity of HSC will be increased significantly. Therefore the use of PP macro-fiber has the best dosage. Moreover, the damage degree of each test group increases with increasing the exposed temperature. Based on the non-linear fitting of the experimental results, the mathematical model of damage degree varying with exposed temperatures was established. According to this model, the exposed temperature of high strength concrete can be calculated by testing the damage degree of concrete after fire.
出处
《硅酸盐通报》
CAS
CSCD
北大核心
2013年第12期2583-2588,共6页
Bulletin of the Chinese Ceramic Society
基金
河北省自然科学基金(E2011203218)资助项目
河北省高等学校科学技术研究(ZD2010114)资助项目
关键词
高强混凝土
聚丙烯粗纤维
残余抗折强度
基体质量损失率
吸水率
high strength concrete
polypropylene macro-fiber
residual flexural strength
matrix mass lossrate
water absorption rate
