聚丙烯粗纤维对高强混凝土高温后性能影响
发布时间：2018-11-19 08:06
【摘要】：高强混凝土结构耐火性问题已经成为当今工程界普遍关注的问题。已有研究表明，在高强混凝土中掺加聚丙烯细纤维，纤维高温熔化后形成的泄压通道，可以缓解爆裂的发生，提高结构耐火性能。与聚丙烯细纤维相比，工程中广泛应用的聚丙烯粗纤维具有相同的材质和熔点，直径却相对较大，高温熔化后形成的泄压通道有所区别，可能会对高强混凝土高温火灾后性能产生不同影响。因此，研究聚丙烯粗纤维对高强混凝土高温后性能的影响十分必要。 本文通过改变聚丙烯纤维的掺量，制备了五组不同配合比的高强混凝土试件，试件尺寸为40mm×40mm×160mm，采用箱式电阻炉进行高温试验（目标温度分别为200℃、400℃、600℃和800℃）。通过研究不同纤维掺量高强混凝土试件高温后的抗压强度和抗折强度的变化规律，分析了聚丙烯粗纤维对高强混凝土高温后力学性能的影响。结果表明：掺加聚丙烯粗纤维有利于提高高强混凝土高温后的残余抗压强度，但会对残余抗折强度产生不利影响，，聚丙烯粗、细纤维混杂协同作用可使不利影响降至最低。通过对基体质量损失率和吸水率的测定，探讨了聚丙烯粗纤维对高强混凝土高温后孔结构的影响，发现：与聚丙烯细纤维相比，聚丙烯粗纤维熔化后形成的泄压通道更为粗化，使得高强混凝土的基体质量损失率及吸水率更大；过高掺量的聚丙烯粗纤维，将使泄压通道过于粗化，混凝土的总孔隙率明显增大。结合超声波无损检测技术，对不同纤维掺量高强混凝土的高温损伤进行了探测，建立了聚丙烯纤维高强混凝土的损伤度随受火温度变化的数学模型，工程中可以依据该模型，推定结构的实际受火温度。 本文将会对高强混凝土结构耐火性设计和正确进行灾后损伤评估具有一定的指导意义。
[Abstract]:The fire resistance of high-strength concrete structures has become a common concern in the engineering field. It has been shown that adding polypropylene fine fiber to high strength concrete can reduce the explosion and improve the fire resistance of the structure by reducing the pressure channel formed by melting the fiber at high temperature. Compared with the polypropylene fine fiber, the coarse polypropylene fiber widely used in engineering has the same material and melting point, but the diameter is relatively large, and the pressure relief channel formed after melting at high temperature is different. It may have different effects on the performance of high strength concrete after high temperature fire. Therefore, it is necessary to study the effect of polypropylene fiber on the properties of high-strength concrete after high temperature. In this paper, five groups of high strength concrete specimens with different blending ratio were prepared by changing the content of polypropylene fiber. The size of the specimens was 40mm 脳 40mm 脳 160 mm. The high temperature test was carried out in a box resistance furnace (the target temperature was 200 鈩
本文编号：2341643
[Abstract]:The fire resistance of high-strength concrete structures has become a common concern in the engineering field. It has been shown that adding polypropylene fine fiber to high strength concrete can reduce the explosion and improve the fire resistance of the structure by reducing the pressure channel formed by melting the fiber at high temperature. Compared with the polypropylene fine fiber, the coarse polypropylene fiber widely used in engineering has the same material and melting point, but the diameter is relatively large, and the pressure relief channel formed after melting at high temperature is different. It may have different effects on the performance of high strength concrete after high temperature fire. Therefore, it is necessary to study the effect of polypropylene fiber on the properties of high-strength concrete after high temperature. In this paper, five groups of high strength concrete specimens with different blending ratio were prepared by changing the content of polypropylene fiber. The size of the specimens was 40mm 脳 40mm 脳 160 mm. The high temperature test was carried out in a box resistance furnace (the target temperature was 200 鈩
本文编号：2341643
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