码头面层纤维混凝土的抗冲击性能与增韧机理

IMPACT RESISTANCE PERFORMANCE AND TOUGHNESS REINFORCING MECHANISM OF FIBER REINFORCED CONCRETE USED ON SURFACE LAYER OF WHARF PAVEMENT

在C30素水泥混凝土中分别添加聚丙烯纤维、尼龙纤维、钢纤维配制纤维混凝土，进行抗弯曲冲击试验。以初裂次数、终裂次数、冲击韧性评价混凝土抗冲击性能的优劣。试验结果表明：添加钢纤维、聚丙烯纤维、尼龙纤维混凝土的冲击韧性分别是素混凝土冲击韧性的15．1倍、3．4倍、2．7倍。结合冲击破坏断裂特征，分析了纤维混凝土承受冲击载荷作用的几种能量吸收机制，对增韧机理进行了分析。钢纤维、聚丙烯纤维、尼龙纤维混凝土，纤维拔出功消耗能量分别是纤维断裂功消耗能量的25倍、1．72倍、0．93倍。纤维的滑移、拔出、断裂是聚丙烯纤维、尼龙纤维混凝土提高抗冲击性能的主要因素，钢纤维混凝土的抗冲击能力提高幅度最大除了纤维的滑移、拔出因素外，还归功于钢纤维对裂纹面的桥接作用。

The fiber reinforced concrete with polypropylene fiber, nylon fiber and steel fiber respectively addedinto C30 plain concrete was used for flexural impact resistance performance experiment. The impact resistance property is evaluated by initial cracking times, final cracking times and impact toughness. The result shows that the impact toughness of steel fiber concrete, polypropylene fiber concrete and nylon fiber concrete is respectively 15.1, 3.4, 2.7 times of the plain concrete. Several energy absorbing mechanisms and toughness reinforcing mechanism were analyzed. The energy consumed by fiber pulling-out work of steel fiber concrete, polypropylene fiber concrete and nylon fiber concrete is respectively 25, 1.72, 0.93 times of the energy consumed by fiber fracture work. Sliding, pulling-out, fracture are major factors to improve the flexural impact resistance of polypropylene fiber, nylon fiber reinforced concrete. Besides sliding and pulling-out, the bridge-making to the crack of steel fiber is very important to improve the impact resistance property of steel fiber reinforced concrete greatly.