纤维混凝土界面性能及纤维作用机理研究
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摘要
水泥混凝土是近代最广泛使用的建筑材料，也是当前最大宗的人造材料。由于混凝土具有良好的耐水性、可塑性和原料来源广、生产工艺简单、生产成本低、应用方便等优点一直为工程界所青睐。从发展趋势来看，在今后相当长的时期内水泥混凝土仍起着不可替代的作用，仍将是应用最广、用量最大的建筑材料。但混凝土的自身缺陷也限制了它的应用范围和效果。纤维混凝土可有效的改善混凝土的性能，所以自纤维混凝土问世以来一直受到国内外研究机构和学者的重视。
本文研究了纤维在混凝土中的作用机理，分析、总结提出了提高纤维混凝土性能的有效方法和途径。
首先研究了纤维与混凝土基体之间界面的粘结性能。从理论方面计算了纤维受力后在脱粘和拔出过程中界面剪应力的变化。并采用弹簧粘结单元用有限元方法模拟了纤维与基体的粘结性能。
其次从两方面分析和研究了纤维对混凝土改性的机理。在混凝土硬化过程中纤维改善了混凝土的内部结构，主要表现在减少了混凝土的塑性裂纹和内部微裂纹的数量和尺寸，提高了混凝土材料介质的连续性，从而改善了混凝土的综合性能。在纤维混凝土受力过程中纤维改变了混凝土基体的应力场，从而改变了纤维混凝土的力学性能。
然后运用断裂力学的观点和方法分析了纤维对混凝土的增强、增韧机理。计算过程中考虑了纤维与混凝土之间相互粘结并滑移的真实过程。在纤维混凝土受力过程中，纤维起到阻止混凝土中原有裂纹以及受力过程中新生裂纹扩展的作用。特别是裂纹上桥联纤维的阻裂作用，使纤维混凝土的强度和韧性得到了不同程度的提高。提高纤维与混凝土界面过渡区的密实度，增加纤维的掺量、长度和表面的粗糙度，都可有效的提高纤维混凝土的强度和韧性。从纤维混凝土的破坏机理出发，推导了纤维混凝土抗拉强度的计算公式。
最后总结了纤维对混凝土改性的机理和提高纤维混凝土性能的有效方法，并对进一步的研究工作提出了建议和设想。
Concrete is most extensively used as architectural materials in latter day and is the largest artificial materials at present. It is prevalent in civil engineering because of its waterproof, plasticity, abundance, cheapness and easy operation. Thus it is believed that nothing can displace concrete as the most extensive architectural materials in a long time. But in the same time the flaws of the concrete prevent itself from application and good effect. The use of fiber concrete can improve the performance of concrete, so it is concerned more and more by research institutions and scholars since it is come into being.
This paper studies the mechanism of changing in fiber concrete and summarizes the methods of improving performance of fiber concrete. The main tasks of the present paper are as follows:
Firstly, the interfacial performance between fibers and concrete is studied. Then the change of shear stress in the interface is deduced in theoretical way after the fibers are disengaged and pulled out from concrete. In addition, the spring element is used to simulate the bond between fibers and concrete in FEM.
Next, the improvement of fibers to concrete is analyzed from two aspects. On the course of hardening of concrete, the improvement of performance mainly lies in the decrease of plasticity cracks and interior cracks of concrete in quantity and in dimension and the enhancement of medium continuity. The stress field of concrete is altered because of the effect of the fibers, which will change the mechanics performance of concrete.
Then, the methods of Fracture Mechanics are adopted to analyze toughness and strength of concrete, which considers the process of slip between fibers and concrete. On the working style of the fiber concrete structure, the fibers make a difference in preventing the fracture cracks from expanding, which improves the strength and toughness to a certain extent. Increasing the density of the transitional field between fibers and concrete structure and increasing the volume fraction, length, and external
roughness of fibers both can improve the strength and toughness of concrete structure
effectively. From the fracture mechanism of fiber concrete structure , some formulations as to the strength of fiber concrete are educed in the paper.
Finally, some effective methods of improving working performance of fiber concrete structure are summed up and several suggestions are put forward for further research.
本文研究了纤维在混凝土中的作用机理，分析、总结提出了提高纤维混凝土性能的有效方法和途径。
首先研究了纤维与混凝土基体之间界面的粘结性能。从理论方面计算了纤维受力后在脱粘和拔出过程中界面剪应力的变化。并采用弹簧粘结单元用有限元方法模拟了纤维与基体的粘结性能。
其次从两方面分析和研究了纤维对混凝土改性的机理。在混凝土硬化过程中纤维改善了混凝土的内部结构，主要表现在减少了混凝土的塑性裂纹和内部微裂纹的数量和尺寸，提高了混凝土材料介质的连续性，从而改善了混凝土的综合性能。在纤维混凝土受力过程中纤维改变了混凝土基体的应力场，从而改变了纤维混凝土的力学性能。
然后运用断裂力学的观点和方法分析了纤维对混凝土的增强、增韧机理。计算过程中考虑了纤维与混凝土之间相互粘结并滑移的真实过程。在纤维混凝土受力过程中，纤维起到阻止混凝土中原有裂纹以及受力过程中新生裂纹扩展的作用。特别是裂纹上桥联纤维的阻裂作用，使纤维混凝土的强度和韧性得到了不同程度的提高。提高纤维与混凝土界面过渡区的密实度，增加纤维的掺量、长度和表面的粗糙度，都可有效的提高纤维混凝土的强度和韧性。从纤维混凝土的破坏机理出发，推导了纤维混凝土抗拉强度的计算公式。
最后总结了纤维对混凝土改性的机理和提高纤维混凝土性能的有效方法，并对进一步的研究工作提出了建议和设想。
Concrete is most extensively used as architectural materials in latter day and is the largest artificial materials at present. It is prevalent in civil engineering because of its waterproof, plasticity, abundance, cheapness and easy operation. Thus it is believed that nothing can displace concrete as the most extensive architectural materials in a long time. But in the same time the flaws of the concrete prevent itself from application and good effect. The use of fiber concrete can improve the performance of concrete, so it is concerned more and more by research institutions and scholars since it is come into being.
This paper studies the mechanism of changing in fiber concrete and summarizes the methods of improving performance of fiber concrete. The main tasks of the present paper are as follows:
Firstly, the interfacial performance between fibers and concrete is studied. Then the change of shear stress in the interface is deduced in theoretical way after the fibers are disengaged and pulled out from concrete. In addition, the spring element is used to simulate the bond between fibers and concrete in FEM.
Next, the improvement of fibers to concrete is analyzed from two aspects. On the course of hardening of concrete, the improvement of performance mainly lies in the decrease of plasticity cracks and interior cracks of concrete in quantity and in dimension and the enhancement of medium continuity. The stress field of concrete is altered because of the effect of the fibers, which will change the mechanics performance of concrete.
Then, the methods of Fracture Mechanics are adopted to analyze toughness and strength of concrete, which considers the process of slip between fibers and concrete. On the working style of the fiber concrete structure, the fibers make a difference in preventing the fracture cracks from expanding, which improves the strength and toughness to a certain extent. Increasing the density of the transitional field between fibers and concrete structure and increasing the volume fraction, length, and external
roughness of fibers both can improve the strength and toughness of concrete structure
effectively. From the fracture mechanism of fiber concrete structure , some formulations as to the strength of fiber concrete are educed in the paper.
Finally, some effective methods of improving working performance of fiber concrete structure are summed up and several suggestions are put forward for further research.
引文
[1] 黄士元，蒋家奋，杨南如等．近代混凝土技术．陕西科学技术出版社，1998，10．
[2] 谷章昭，倪梦象．合成纤维混凝土的性能及其工程应用．建筑材料学报，1999，2(2)：159-162
[3] 许达，高小青．C F纤维混凝土的性能试验与研究．铁道标准设计，2002，(6)：55-58
[4] 王成启，吴科如．不同弹性模量的纤维对高强混凝土力学性能的影响．混凝土与水泥制品，2002，6：36-37
[5] 邓家才，孙成栋，黄博升．碳纤维混凝土的压缩韧度指数[J]．混凝土与水泥制品，2000,(4)：37-38
[6] Jun Zhang, Henrik Stang, Victor C. Li. Experimental study on crack bridging in FRC under uniaxial fatigue tension. Journal of Material in Civil Engineering, 2000,2:66-73
[7] 华渊，曾艺．纤维混杂效应的试验研究[J]．混凝土与水泥制品，1998，(4)：45-49
[8] 孙伟，钱红萍，陈惠苏．纤维混杂及其与膨胀剂复合对水泥基材料的物理性能的影响[J]．硅酸盐学报，2000，28(2)：95-99
[9] Mazar,J, Pijaudier-Cabot,G. From Damage to Fracture Mechanics and Conversely-A Combined Approach. Proceeding of Engineering Mechanica,ASCE, 1995,231-234
[10] Mohamed Boulfiza, Nemkumar Banthia,and Koji Sakai. Application of Continuum Damage Mechanics to Carber Fiber-Reinforced Cement Composites. ACI Materials Journal, 2000,5:245-253
[11] 蔡敏，蔡四维．纤维混凝土疲劳裂纹扩展分析[J]．东南大学学报，1998，28(5)：108-111
[12] 蔡四维，蔡敏．混凝土的损伤与断裂[M]．北京：人民交通出版社，1999，50-55．
[13] 王为农，姜艳书，张洪福．改性聚丙烯纤维混凝土在防渗工程上的应用．产业用纺织品，2000，112(18)：27-28
[14] 亚当·内维尔．纤维增强水泥与混凝土(第一册)．杨顺喜，田恒译．中国建筑工业出版社，1980，12：19-20
[15] 陈鼎，樊述斌．钢纤维硅粉混凝土在三峡工程中的应用研究．建筑石膏与胶凝材料，1998(1)：28-30
[16] 杨元霞，毛起炤，沈大荣等．碳纤维水泥基复合材料中纤维分散性的研究，新型建筑材料2001，4(1)：84-88
[17] 申豫斌，谢慧才．碳纤维水泥砂浆的配制及力学性能测试，混凝土，2001(7)：48-51
[18] Naamann A.E.Exploring. A New High Performance Concrete SIFCON. Cement in the Future, 1991,3(1)
[19] Parameswaran V.S.et.al. Behavior of High Volume Fibre Cement Mortar in Flexure,Cement and Concrete Composite, 1990,3(4)
[20] 吕西林，金国芳，吴晓涵．钢筋混凝土结构非线性有限元理论与应用，同济大学出版社，1999．
[21] 金芷生等，钢纤维与水泥砂浆粘结性能研究．哈尔滨：全国第二界纤维水泥与纤维混凝土学术会议论文集，1988。
[22] 李丽，秦鸿根．钢纤维与水泥砂浆界面粘结性能的试验研究．洛阳大学学报．2002，17(4)：82～85
[23] M. Jamal Shannag, Rune Brincker, Will Hansen. Pullout behavior of steel fibers from cement-based composites. Cement and Concrete Research, 1997, 27 (6): 925-936
[24] Karihaloo,B.L, J.Wang, Graybowski,M. Doubly periodic arrays of bridged cracks and short fibre-reinforced cementitious composites. Journal of the Mechanics and Physics of Solids, 1996, 44 (10): 1565-1586
[25] Peter Kohnke, Ph. D. ANSYS Element Reference(Release 5.6). 1999
[26] H.Yuan, J.G .Teng, R. Seracino. Full-range behivior of FRP-to-concrete bonded joints. Engineering Structure, 2003
[27] 高丹盈，刘建秀．钢纤维混凝土基本理论．科学技术文献出版社，1994，12：187-188
[28] Canan Tasdemir, Mehmet A.Tasdemir, Frank D.Lydon. Effects of silica fume and aggregate size on the brittleness of concrete. Cement and Concrete Research, 1996, 26(1): 63-68
[29] Christopher K.Y.Leung, Geng Yiping. Effect of lateral stresses on fiber debonding/pull-out. Composites Engineering, 1995, 5 (10-11): 1331-1348
[30] Qing-Sheng Yang, Qing-Hua Qin, Xi-Rong Peng. Size effects in the fiber pullout test. Composite Structures. 2003, 61(3): 193-198
[31] P·梅泰．混凝土的结构、性能与材料，祝永年，沈威，陈志源译．同济大学出版社，1991，12-27
[32] 龚益，沈荣熹，李清海．杜拉纤维在土建工程中的应用，机械工业出版社，2002．10
[33] 徐芝纶．弹性力学简明教程(第二版)，高等教育出版社，1983．5
[34] 过镇海．混凝土的强度和变形试验基础和本构关系．北京：青华大学出版社，1997：83～84
[35] 李永录．偏心受拉载荷下混凝土的应力-应变关系：[硕士论文]．北京：清华大学，1988
[36] 尹双增．断裂·损伤理论及应用．清华大学出版社(第1版)．1992
[37] Peter Kohnke, Ph. D. ANSYS Theory Reference(Release 5.6). 1999:19-44～19-47
[38] 王铎．断裂力学。广西人民出版社．1982：87～88
[39] 赵建生．断裂力学及断裂物理．华中科技大学出版社．2003
[40] Romualdi,J.P, Mandel,J.A. Tensile strength of concrete affected by uniformly distributed and closely short lengths of wire reinforcement. ACI Journal Proceedings, 1964,61(6):657-670
[41] 王铁梦．工程结构裂缝控制．中国建材工业出版社，1999：12
[42] 程铁生，章文刚，吴爱中．钢纤维混凝土抗拉性能的研究，全国第三届纤维水泥与纤维混凝土学术会议论文集．Vol．3 1990：1～21
[2] 谷章昭，倪梦象．合成纤维混凝土的性能及其工程应用．建筑材料学报，1999，2(2)：159-162
[3] 许达，高小青．C F纤维混凝土的性能试验与研究．铁道标准设计，2002，(6)：55-58
[4] 王成启，吴科如．不同弹性模量的纤维对高强混凝土力学性能的影响．混凝土与水泥制品，2002，6：36-37
[5] 邓家才，孙成栋，黄博升．碳纤维混凝土的压缩韧度指数[J]．混凝土与水泥制品，2000,(4)：37-38
[6] Jun Zhang, Henrik Stang, Victor C. Li. Experimental study on crack bridging in FRC under uniaxial fatigue tension. Journal of Material in Civil Engineering, 2000,2:66-73
[7] 华渊，曾艺．纤维混杂效应的试验研究[J]．混凝土与水泥制品，1998，(4)：45-49
[8] 孙伟，钱红萍，陈惠苏．纤维混杂及其与膨胀剂复合对水泥基材料的物理性能的影响[J]．硅酸盐学报，2000，28(2)：95-99
[9] Mazar,J, Pijaudier-Cabot,G. From Damage to Fracture Mechanics and Conversely-A Combined Approach. Proceeding of Engineering Mechanica,ASCE, 1995,231-234
[10] Mohamed Boulfiza, Nemkumar Banthia,and Koji Sakai. Application of Continuum Damage Mechanics to Carber Fiber-Reinforced Cement Composites. ACI Materials Journal, 2000,5:245-253
[11] 蔡敏，蔡四维．纤维混凝土疲劳裂纹扩展分析[J]．东南大学学报，1998，28(5)：108-111
[12] 蔡四维，蔡敏．混凝土的损伤与断裂[M]．北京：人民交通出版社，1999，50-55．
[13] 王为农，姜艳书，张洪福．改性聚丙烯纤维混凝土在防渗工程上的应用．产业用纺织品，2000，112(18)：27-28
[14] 亚当·内维尔．纤维增强水泥与混凝土(第一册)．杨顺喜，田恒译．中国建筑工业出版社，1980，12：19-20
[15] 陈鼎，樊述斌．钢纤维硅粉混凝土在三峡工程中的应用研究．建筑石膏与胶凝材料，1998(1)：28-30
[16] 杨元霞，毛起炤，沈大荣等．碳纤维水泥基复合材料中纤维分散性的研究，新型建筑材料2001，4(1)：84-88
[17] 申豫斌，谢慧才．碳纤维水泥砂浆的配制及力学性能测试，混凝土，2001(7)：48-51
[18] Naamann A.E.Exploring. A New High Performance Concrete SIFCON. Cement in the Future, 1991,3(1)
[19] Parameswaran V.S.et.al. Behavior of High Volume Fibre Cement Mortar in Flexure,Cement and Concrete Composite, 1990,3(4)
[20] 吕西林，金国芳，吴晓涵．钢筋混凝土结构非线性有限元理论与应用，同济大学出版社，1999．
[21] 金芷生等，钢纤维与水泥砂浆粘结性能研究．哈尔滨：全国第二界纤维水泥与纤维混凝土学术会议论文集，1988。
[22] 李丽，秦鸿根．钢纤维与水泥砂浆界面粘结性能的试验研究．洛阳大学学报．2002，17(4)：82～85
[23] M. Jamal Shannag, Rune Brincker, Will Hansen. Pullout behavior of steel fibers from cement-based composites. Cement and Concrete Research, 1997, 27 (6): 925-936
[24] Karihaloo,B.L, J.Wang, Graybowski,M. Doubly periodic arrays of bridged cracks and short fibre-reinforced cementitious composites. Journal of the Mechanics and Physics of Solids, 1996, 44 (10): 1565-1586
[25] Peter Kohnke, Ph. D. ANSYS Element Reference(Release 5.6). 1999
[26] H.Yuan, J.G .Teng, R. Seracino. Full-range behivior of FRP-to-concrete bonded joints. Engineering Structure, 2003
[27] 高丹盈，刘建秀．钢纤维混凝土基本理论．科学技术文献出版社，1994，12：187-188
[28] Canan Tasdemir, Mehmet A.Tasdemir, Frank D.Lydon. Effects of silica fume and aggregate size on the brittleness of concrete. Cement and Concrete Research, 1996, 26(1): 63-68
[29] Christopher K.Y.Leung, Geng Yiping. Effect of lateral stresses on fiber debonding/pull-out. Composites Engineering, 1995, 5 (10-11): 1331-1348
[30] Qing-Sheng Yang, Qing-Hua Qin, Xi-Rong Peng. Size effects in the fiber pullout test. Composite Structures. 2003, 61(3): 193-198
[31] P·梅泰．混凝土的结构、性能与材料，祝永年，沈威，陈志源译．同济大学出版社，1991，12-27
[32] 龚益，沈荣熹，李清海．杜拉纤维在土建工程中的应用，机械工业出版社，2002．10
[33] 徐芝纶．弹性力学简明教程(第二版)，高等教育出版社，1983．5
[34] 过镇海．混凝土的强度和变形试验基础和本构关系．北京：青华大学出版社，1997：83～84
[35] 李永录．偏心受拉载荷下混凝土的应力-应变关系：[硕士论文]．北京：清华大学，1988
[36] 尹双增．断裂·损伤理论及应用．清华大学出版社(第1版)．1992
[37] Peter Kohnke, Ph. D. ANSYS Theory Reference(Release 5.6). 1999:19-44～19-47
[38] 王铎．断裂力学。广西人民出版社．1982：87～88
[39] 赵建生．断裂力学及断裂物理．华中科技大学出版社．2003
[40] Romualdi,J.P, Mandel,J.A. Tensile strength of concrete affected by uniformly distributed and closely short lengths of wire reinforcement. ACI Journal Proceedings, 1964,61(6):657-670
[41] 王铁梦．工程结构裂缝控制．中国建材工业出版社，1999：12
[42] 程铁生，章文刚，吴爱中．钢纤维混凝土抗拉性能的研究，全国第三届纤维水泥与纤维混凝土学术会议论文集．Vol．3 1990：1～21