高强高韧性桥面铺装混凝土制备及其性能研究
发布时间：2018-12-12 06:34
【摘要】：水泥混凝土由于原材料丰富、强度高、刚度大和性价比高等优点而成为重要的桥面铺装材料之一。但水泥混凝土的抗拉强度低、脆性大，易开裂，因而在交通荷载、自然因素与收缩应力等综合作用下，较易出现裂缝和断裂等病害，且病害一旦形成，修复难度较大，将严重影响桥梁的安全性和桥面铺装的耐久性。本文采用混杂纤维增强技术手段，综合考虑混凝土工作性、力学性能和弯曲性能，从多尺度角度对混凝土进行了增强增韧设计，制备出了具有变形硬化特征的高强高韧性水泥混凝土桥面铺装材料，并对其性能进行了深入研究。 论文从单纤维增强混凝土入手，对聚乙烯纤维（PE）混凝土和聚丙烯粗合成纤维（CPP）混凝土的力学性能和弯曲性能进行了研究。结果表明，单纤维混凝土抗压强度可达60MPa，单纤维混凝土的变形性能有所改善，混凝土荷载-挠度曲线由脆性破坏变为变形急速软化，具有一定的裂后承载能力，但混凝土的弯曲韧性仍较差，单纤维增韧方式不能使混凝土获得高韧性。 基于混凝土多相、多尺度层次的非均质结构特性，结合单纤维增韧的试验结果，本文采用了两种不同性质和不同尺度的纤维混杂增强增韧体系——聚乙烯纤维与聚丙烯粗合成纤维混杂体系，对混凝土内不同结构和性能层次进行了逐级强化与增韧，制备出了高强高韧性混杂纤维混凝土，并通过抗压强度试验、四点弯曲试验、纤维/基体界面改性试验和耐磨性试验对混杂纤维混凝土性能进行了全面研究。结果表明，混凝土抗压强度超过60MPa，抗弯拉强度可达8MPa；混凝土弯曲性能显著提高，，荷载-挠度曲线饱满并具备变性硬化特征，裂后承载保持能力较强；混杂纤维混凝土的韧性指数与残余强度系数明显提高，均超过理想弹塑性材料，抗弯拉韧性水平多数为3，部分可达4；CPP纤维/基体界面改性后，粘结强度提高，界面区结构更为密实，界面微结构得以强化，在宏观上可延缓大裂缝的扩展与混凝土的破坏，辅助细观尺度的增韧，有效提高混凝土的弯曲韧性；材料耐磨性与抗渗性随粗集料体积水平提高而降低，因此粗集料水平不宜过高。
[Abstract]:Cement concrete has become one of the important bridge deck paving materials because of its rich raw materials, high strength, high stiffness and high cost performance. However, cement concrete has low tensile strength, high brittleness and easy cracking. Therefore, under the combined action of traffic load, natural factors and shrinkage stress, cracks and fractures are more likely to occur, and once the disease is formed, it is difficult to repair. It will seriously affect the safety of bridge and the durability of deck pavement. In this paper, the reinforcement and toughening design of concrete is carried out from the angle of multi-scale by means of hybrid fiber reinforcement technology and considering the workability, mechanical properties and flexural properties of concrete. The high strength and high toughness cement concrete bridge deck pavement materials with deformation hardening characteristics were prepared and their properties were studied. In this paper, the mechanical properties and bending properties of polyethylene fiber (PE) concrete and polypropylene coarse synthetic fiber (CPP) concrete are studied from the point of view of single fiber reinforced concrete. The results show that the compressive strength of single fiber concrete can reach 60 MPA, the deformation performance of single fiber concrete has been improved, the load-deflection curve of concrete has changed from brittle failure to deformation and rapid softening, and it has certain post-crack bearing capacity. However, the flexural toughness of concrete is still poor, and the single fiber toughening method can not make concrete obtain high toughness. Based on the heterogeneous structure characteristics of concrete with multi-phase and multi-scale, combined with the test results of single fiber toughening, In this paper, two kinds of fiber hybrid toughening systems of different properties and different scales, polyethylene fiber and polypropylene coarse synthetic fiber hybrid system, are used to strengthen and toughen the different structures and properties of concrete step by step. High strength and high toughness hybrid fiber reinforced concrete was prepared. The properties of hybrid fiber reinforced concrete were studied by compressive strength test, four-point bending test, fiber / matrix interface modification test and wear resistance test. The results show that the compressive strength of concrete is more than 60 MPA and the flexural tensile strength is up to 8 MPA, the flexural property of concrete is improved significantly, the load-deflection curve is full and has the characteristics of denaturation and hardening, and the load-bearing capacity of the concrete after crack is relatively strong. The toughness index and residual strength coefficient of hybrid fiber reinforced concrete are higher than that of ideal elastoplastic material. The flexural and tensile toughness level of hybrid fiber reinforced concrete is mostly 3 and some of them can reach 4. After the modification of CPP fiber / matrix interface, the bond strength is increased, the structure of interface area is more dense, and the interface microstructure is strengthened, which can delay the propagation of large cracks and the destruction of concrete macroscopically, and assist in the toughening of meso-scale. Effectively improve the flexural toughness of concrete; The wear-resistance and impermeability of the materials decrease with the increase of the volume level of coarse aggregate, so the level of coarse aggregate should not be too high.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U444;U443.33
[Abstract]:Cement concrete has become one of the important bridge deck paving materials because of its rich raw materials, high strength, high stiffness and high cost performance. However, cement concrete has low tensile strength, high brittleness and easy cracking. Therefore, under the combined action of traffic load, natural factors and shrinkage stress, cracks and fractures are more likely to occur, and once the disease is formed, it is difficult to repair. It will seriously affect the safety of bridge and the durability of deck pavement. In this paper, the reinforcement and toughening design of concrete is carried out from the angle of multi-scale by means of hybrid fiber reinforcement technology and considering the workability, mechanical properties and flexural properties of concrete. The high strength and high toughness cement concrete bridge deck pavement materials with deformation hardening characteristics were prepared and their properties were studied. In this paper, the mechanical properties and bending properties of polyethylene fiber (PE) concrete and polypropylene coarse synthetic fiber (CPP) concrete are studied from the point of view of single fiber reinforced concrete. The results show that the compressive strength of single fiber concrete can reach 60 MPA, the deformation performance of single fiber concrete has been improved, the load-deflection curve of concrete has changed from brittle failure to deformation and rapid softening, and it has certain post-crack bearing capacity. However, the flexural toughness of concrete is still poor, and the single fiber toughening method can not make concrete obtain high toughness. Based on the heterogeneous structure characteristics of concrete with multi-phase and multi-scale, combined with the test results of single fiber toughening, In this paper, two kinds of fiber hybrid toughening systems of different properties and different scales, polyethylene fiber and polypropylene coarse synthetic fiber hybrid system, are used to strengthen and toughen the different structures and properties of concrete step by step. High strength and high toughness hybrid fiber reinforced concrete was prepared. The properties of hybrid fiber reinforced concrete were studied by compressive strength test, four-point bending test, fiber / matrix interface modification test and wear resistance test. The results show that the compressive strength of concrete is more than 60 MPA and the flexural tensile strength is up to 8 MPA, the flexural property of concrete is improved significantly, the load-deflection curve is full and has the characteristics of denaturation and hardening, and the load-bearing capacity of the concrete after crack is relatively strong. The toughness index and residual strength coefficient of hybrid fiber reinforced concrete are higher than that of ideal elastoplastic material. The flexural and tensile toughness level of hybrid fiber reinforced concrete is mostly 3 and some of them can reach 4. After the modification of CPP fiber / matrix interface, the bond strength is increased, the structure of interface area is more dense, and the interface microstructure is strengthened, which can delay the propagation of large cracks and the destruction of concrete macroscopically, and assist in the toughening of meso-scale. Effectively improve the flexural toughness of concrete; The wear-resistance and impermeability of the materials decrease with the increase of the volume level of coarse aggregate, so the level of coarse aggregate should not be too high.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U444;U443.33
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