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靠压缩空气把砂浆或混凝土高速喷射在一表面上的喷射混凝土,在诸如隧洞内衬和斜坡稳固等应用方面已有几十年的历史了。早在70年代初,占整个混合物体积2%的钢纤维就已开始取代喷射混凝土中的钢丝网增强材料,并在岩石斜坡稳固、矿井和隧道内衬以及薄壳结构物中得到了广泛的应用。用聚丙烯纤维增强的喷射混凝土于1968年首次在欧洲使用,但大量使用聚丙烯纤维(每立方米5.93kg)直到1988年才成功地掺合在喷射混凝土中。关于钢纤维,美国混凝土协会有关纤维增强喷射混凝土的报告中是这样提出的:“短纤维容易混合和喷射,回弹也较少,但喷射混凝土的韧性和抗后期开裂性较差;长纤维虽然在强度和韧性方面优于短纤维,但喷射时经常堵塞,且回弹速率比较大”。鉴于这种情况,现在普通规定钢纤维的长度在25.4mm范围
Shotcrete, which uses compressed air to spray mortar or concrete onto a surface at high speed, has been used for decades in applications such as tunnel linings and slope stabilization. As early as in the early 1970s, steel fibers, which accounted for 2% of the entire mixture volume, had begun to replace wire mesh reinforcements in shotcrete and were widely used in rock slope stabilization, mine shaft and tunnel linings, and thin shell structures. . Polypropylene fiber reinforced shotcrete was first used in Europe in 1968, but extensive use of polypropylene fiber (5.93 kg per cubic meter) was not successfully blended into shotcrete until 1988. Regarding steel fibers, the American Concrete Association’s report on fiber-reinforced shotcrete is such that: “Short fibers are easy to mix and spray and have less rebound, but shotcrete is less tough and resistant to cracking at later stages; long fibers, though It is superior to short fiber in strength and toughness, but it is often clogged when injected, and the rebound rate is relatively large." In view of this situation, it is now generally specified that the length of steel fibers is in the range of 25.4mm.