【作者】 李建辉；

【导师】 邓宗才；

【作者基本信息】 北京工业大学 ， 结构工程， 2006， 硕士

【摘要】 粗合成纤维兴起于20世纪末,它是一种新型的增强增韧材料,相对于钢纤维、细合成纤维,它具有明显的竞争优势:(1)质轻;(2)无腐蚀;(3)易于均匀分散;(4)显著提高混凝土的韧性、抗冲击、抗疲劳、抗震防爆性能;(5)可以提高塑性混凝土的早期抗裂性能;(6)在喷射混凝土中具有显著的优势。粗合成纤维混凝土在美国和日本等国家已有多年的使用历史,其显著的效果已为大量工程实践所证明,它已成为水泥基复合材料的未来发展方向。本论文首先对粗合成纤维混凝土的力学特性进行了一系列试验研究,其中包括:(1)抗弯试验;(2)抗弯冲击试验;(3)轴向拉拔试验;(4)单轴拉伸试验;(5)抗震试验;(6)抗疲劳试验;(7)抗氯离子腐蚀试验;(8)混杂纤维混凝土的力学性能试验。通过对粗合成纤维混凝土抗弯韧性试验数据的分析,基于美国ASTM及日本JSCE方法,提出了粗合成纤维混凝土抗弯韧性新评价方法,该韧性评价方法能够准确地反映粗合成纤维的阻裂增韧效果。国内外大部分关于纤维混凝土抗冲击性能研究均采用抗冲压试验,而实际工程中构件多处于受弯拉状态。自行研制了落锤式抗弯冲击试验装置,该装置的研制成功,为今后系统研究纤维混凝土抗弯冲击性能具有重要意义。针对冲击试验数据较离散的缺陷,本论文引入数理统计方法对冲击试验数据进行分析,统计分析结果较全面、客观的反映了纤维混凝土动载特性。本论文首次完成了柔性粗纤维的拉拔试验,重点研究了纤维埋置长度、养护龄期、基体强度对粗合成纤维-砂浆基体界面粘结强度的影响。通过对拉拔荷载-位移曲线进行拟合,建立异型柔性纤维的拉拔理论模型,理论模拟曲线与试验曲线吻合良好,它的提出对粗合成纤维细观增强机理的深入研究具有较高的实用价值和理论意义。由于混凝土自身是多相、多组分、多尺度层次的非均质结构特性,单一纤维增强作用是有限的,混杂纤维能在不同结构和不同性能层次上逐级阻裂与强化,达到取长补短的作用。本文试验研究了粗合成纤维与钢纤维混杂纤维混凝土的韧性及断裂性能,试验结果充分体现了粗合成纤维与钢纤维良好的协同效应,它为更多还原

【Abstract】 Synthetic maro-fiber is a new type reinforcement material that appeared in the last of 20th century. When compared to steel fiber and synthetic micro-fiber, the synthetic macro-fiber offers a large number of advantages: (1) light; (2) evenly distributed; (3) erosion resistance; (4) obviously improves the impact resistance, flexural toughness, fatigue and seismic properties; (5) resistance for early crack; (6) prominent advantage in shotcrete. Synthetic macro-fiber reinforced concrete have been used for many years in USA, Japan and so on, and achieved remarkable effect, it provides a development orientation of cement matrix composites in the future.A series of tests are firstly conducted in this paper, and they are: (1) flexural test; (2) flexural impact test; (3) pull-out test; (4) uniaxial tension test; (5) seismic performance test; (6) fatigue test; (7) erosion resistance test; (8) mechanical properties tests of hybrid fiber reinforced concrete.According to analyze experimental data of flexural toughness test of synthetic macro-fiber reinforced concrete, based on ASTM and JSCE method, a new flexural toughness evaluating method is first proposed, it may well and truly reflect toughen and crack arrest of synthetic macro-fiber.In home and abroad, most of research works about impact performance of fiber reinforced concrete (FRC) are under compress, but members of practical structure are under flexural. New type drop weight flexural impact equipment is developed, which has important ideas for researching systematically flexural impact properties of FRC. Aiming at dispersion of impact experimental data is large, statistic analyses method is conducted, and it can reflected roundly impact properties of FRC.Pull-out test of flexible macro-fiber is conducted firstly, this paper is emphasized effects of fiber embedded length, cured times and matrix strength on bonding strength between synthetic macro-fiber and mortar. Based on the experimental observations, a new mechanical model for analysis of shaped flexible fiber is first developed, a good agreement is achieved between the predicted and the experiment results. It has good practical and academic value for research of interfacial bonding between shaped synthetic macro-fiber and matrix.For concrete consisting of hardened cement, aggregates, pore and micro-cracks of different sizes, reinforcing effects of only one type of fiber are limited, however,更多还原