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当前位置:钢纤维混凝土的现状及发展
钢纤维混凝土的现状及发展
[来源:http://www.gangxianwei51.com] [作者:不详] [日期:17-03-18] [浏览次数:]
钢纤维混凝土(SFRC)是在普通混凝土中掺入适量短钢纤维而形成的可浇筑、可喷射成型的一种新型复合材料,近年来在国内外得到迅速发展。它克服了混凝土抗拉强度低、极限延伸率小、性脆等缺点,具有优良的抗拉、抗弯、抗剪、阻裂、耐疲劳、高韧性等性能,已在水工、路桥、建筑等工程领域得到应用。 Steel fiber reinforced concrete (SFRC) is in the common concrete mixed with proper amount of short steel fiber formed by casting, injection molding of a new type of composite materials, rapid development in recent years at home and abroad. It overcomes the low tensile strength, small ultimate elongation of concrete, such as sexual brittle faults, it has excellent tensile, bending, shear, crack resistance, fatigue resistance, high toughness, such as performance, has been in the field of hydraulic, luqiao, construction and other engineering applications. 一、钢纤维混凝土的发展 First, the development of the steel fiber reinforced concrete 纤维混凝土(FRC),是纤维增强混凝土的简称,通常是以水泥净浆、砂浆或者混凝土为基体,以金属纤维、无机纤维或有机纤维增强材料组成的一种水泥基复合材料。它是将短而细的,具有高抗拉强度、高极限延伸率、高抗碱性的纤维均匀地分散在混凝土基体中形成的一种新型建筑材料。纤维在混凝土中可限制混凝土早期裂缝的产生及在外力作用下裂缝的进一步扩展,有效克服混凝土抗拉强度低、易开裂、抗疲劳性能差等固有缺陷,同时可大幅度提高混凝土的抗渗、防水、抗冻、护筋性等方面的性能。纤维混凝土尤其是钢纤维混凝土,由于其优越的性能,在实际工程中日益得到学术界和工程界的关注。1907年苏联专家B.П.HekpocaB开始用金属纤维增强混凝土;1910年,美国H.F.Porter发表了有关短纤维增强混凝土的研究报告,建议把短钢纤维均匀地分散在混凝土中用以强化基体材料;1911年,美国Graham曾把钢纤维掺入普通混凝土中,提高混凝土强度和稳定性;到20世纪40年代,美、英、法、德、日等国先后做了许多关于用钢纤维来提高混凝土耐磨性和抗裂性、钢纤维混凝土制造工艺、改进钢纤维形状以提高纤维与混凝土基体的黏结强度等方面的研究;1963年J.P.Romualdi和G.B.Batson发表了关于钢纤维约束混凝土裂缝开展机理的论文,提出了钢纤维混凝土开裂强度是由对拉伸应力起有效作用的钢纤维平均间距所决定的结论(纤维间距理论),从而开始了这种新型复合材料的实用开发阶段。到目前,随着钢纤维混凝土的推广应用,因纤维在混凝土中的分布情况不同,主要有四类:钢纤维混凝土、混杂纤维混凝土、层布式钢纤维混凝土和层布式混杂纤维混凝土。 Fiber reinforced concrete (FRC), which is short for fiber reinforced concrete, net pulp, usually in cement mortar or concrete as the matrix, with metal fiber, inorganic or organic fiber reinforced materials consisting of a cement base composite material. It is short and thin, with high tensile strength, high elongation and high limit of alkaline fibre evenly dispersed in the concrete substrate in the form of a new type of building materials. Fiber in concrete can limit the formation of early concrete cracks and under the action of external force further extension of cracks, effectively overcome the low concrete tensile strength, easy cracking and poor fatigue resistance inherent defects, at the same time can greatly improve the impermeability of concrete, waterproof, the performance of the antifreeze, protection of reinforcement, etc. Fiber concrete steel fiber reinforced concrete, in particular, due to its superior performance, in the practical engineering are getting the attention of academia and engineering. In 1907, the Soviet union experts b. П. HekpocaB start with metal fiber reinforced concrete; In 1910, the United States H.F.P orter published studies of short fiber reinforced concrete report, suggested that the short steel fiber evenly dispersed in the concrete to reinforce substrate materials; In 1911, the United States, Graham was the steel fiber mixed with ordinary concrete, the concrete strength and stability; In the 1940 s, the United States, Britain, France, Germany, Japan and other countries have made a lot of steel fiber to improve the abrasion resistance and crack resistance of concrete, steel fiber reinforced concrete manufacturing process, improve the steel fibre shape in order to improve the compressive strength of fiber and matrix of concrete research; 1963 J.P.R omualdi and G.B.B atson published papers about steel fiber constraint mechanism of concrete crack, puts forward the cracking strength of steel fiber reinforced concrete is the effective effect to the tensile stress of steel fiber is determined by the average spacing of conclusion (fiber spacing theory), and thus began the practical development of this new type of composites. Up to now, with the application of steel fiber reinforced concrete, because of the fiber in the concrete distribution is different, there are four main categories: hybrid fiber concrete, steel fiber concrete, layer cloth type steel fiber reinforced concrete and cloth type hybrid fiber concrete. 二、钢纤维混凝土的增强机理 Second, the action mechanism of steel fiber reinforced concrete 1. 复合力学理论。复合力学理论是以连续纤维复合材料理论为基础,结合钢纤维在混凝土中的分布特点形成的。该理论是将复合材料视为以纤维为一相、基体为另一相的两相复合材料。 1. The composite mechanics theory. Composite mechanics theory is based on continuous fiber composite material theory, combining with the characteristics of steel fiber concrete in the distribution. The theory is to composite material is seen as a phase for fiber, matrix for another phase of two-phase composite materials. 2. 纤维间距理论。纤维间距理论又称阻裂理论,是根据线弹性断裂力学而提出的,该理论认为纤维的增强作用仅与均匀分布的纤维间距(最小间距)有关。 2. The fiber spacing theory. Fiber spacing theory is also called the crack resistance theory, are proposed according to the linear elastic fracture mechanics, the theory is that fiber enhancement effect only with uniform distribution of fiber spacing (minimum distance). 三、钢纤维混凝土的发展现状分析 Third, the development situation of steel fiber reinforced concrete analysis 1. 钢纤维混凝土。钢纤维混凝土是在普通混凝土中掺入少量低碳钢、不锈钢和玻璃钢的纤维后形成的一种比较均匀而多向配筋的混凝土。钢纤维的掺入量按体积一般为1%~2%,而按重量计每立方米混凝土中掺70~100kg钢纤维,钢纤维的长度宜为25~60mm,直径为0.25~1.25mm,长度与直径的最佳比值为50~700。与普通混凝土相比,它不仅能改善抗拉、抗剪、抗弯、抗磨和抗裂性能,而且能大大增强混凝土的断裂韧性和抗冲击性能,显著提高结构的抗疲劳性能及其耐久性,尤其是韧性可增加10~20倍。我国对钢纤维混凝土与普通混凝土力学性能做了比较试验,当钢纤维掺入量为15%~20%、水灰比为0.45时,其抗拉强度增长50%~70%,抗弯强度增长120%~180%,抗冲击强度增长10~20倍,抗冲击疲劳强度增长15~20倍,抗弯韧性增长14~20倍,耐磨损性能也明显改善。因此,钢纤维混凝土比素混凝土具有更优越的物理和力学性能。 1. Steel fiber reinforced concrete. Steel fiber reinforced concrete is in the ordinary concrete added a small amount of low carbon steel, stainless steel and glass fiber reinforced plastic fiber after the formation of a more uniform and multidirectional reinforcement of concrete. Steel fiber mortar is commonly 1% ~ 2% by volume, and weight meter per cubic meter of 70 ~ 100 kg of steel fiber in concrete, steel fiber length appropriate for 25 ~ 60 mm, 0.25 ~ 1.25 mm diameter, length and the diameter of the best ratio of 50 ~ 700. Compared with ordinary concrete, it can not only improve the tensile, shear, bending, anti-wear and crack resistance, and can greatly enhance the fracture toughness and impact resistance of concrete, significantly improve the anti-fatigue performance and durability of the structure, especially the toughness increases 10 to 20 times. Mechanical properties of steel fiber reinforced concrete and ordinary concrete in our country do the comparison test, when steel fiber mixed with 15% ~ 15%, water cement ratio of 0.45, the tensile strength increased by 50% ~ 70%, the flexural strength increased by 120% ~ 120%, the impact strength increased 10 ~ 20 times, the impact fatigue strength increase 15 ~ 20 times, flexural toughness increase 14 ~ 20 times, wear-resisting performance is obviously improved. Therefore, steel fiber reinforced concrete is better than plain concrete has excellent physical and mechanical properties. 2. 混杂纤维混凝土。有关研究资料表明,钢纤维对混凝土的抗压强度并无明显促进作用,甚至还有所降低;与素混凝土相比,对于钢纤维混凝土的抗渗性、耐磨性、耐冲磨性及对防止混凝土早期塑性收缩等还存在正反(提高与降低)两方面甚至居中的观点。此外,钢纤维混凝土还存在用量较大、价格较高、生锈、对火灾引起的爆裂几乎无抵抗性等问题,使其应用受到了不同程度的影响。近些年来,一些国内外学者开始将目光投向混杂纤维混凝土(HFRC),试图把具有不同性能和优点的纤维混杂,取长补短,在不同层次和受荷阶段发挥“正混杂效应”来增强混凝土各项性能,以适应不同工程的需要。但是关于它的各种力学性能,尤其是其疲劳变形及疲劳损伤在静、动荷载以及等幅或变幅循环荷载作用下的变形发展规律和损伤特性,纤维的最佳掺配量、混杂比例,复合材料各组分的关系,增强效果及增强机理,抗疲劳性能,破坏机理,施工工艺,配合比设计等方面的问题还有待进一步研究。 2. The hybrid fiber concrete. Relevant research data show that the steel fiber on the compressive strength of concrete and no obvious promoting effect, or even lower; Compared with plain concrete, with steel fiber reinforced concrete permeability resistance, abrasion resistance, resistance to impact mill and to prevent early plastic shrinkage of concrete, etc. There are positive and negative (increase and decrease) and even in the point of view. In addition, the dosage of steel fiber reinforced concrete is larger, the price is higher, rust, caused by fire burst almost no resistance, make its application by the influence of different level. At home and abroad in recent years, some scholars began to look to hybrid fiber concrete (HFRC), trying to mix with different performance and advantages of fiber, complement each other, at different levels and the loading stage play a "positive hybrid effect" to enhance the performance of concrete, so as to adapt to the needs of different projects. But about its various mechanical properties, especially its fatigue deformation and fatigue damage in the static, dynamic load and constant amplitude and variable amplitude cyclic loading of deformation and damage characteristics, the development of the best blending fiber, mixed proportion, relationship of various components of composite materials, enhancement effect and strengthen mechanism of anti-fatigue performance, failure mechanism, construction technology, the mixture ratio design problems remains to be further research. 3. 层布式钢纤维混凝土。整体式纤维混凝土由于其不易搅拌均匀、纤维易结团、纤维用量较大、造价比较高等问题,影响到它大面积的推广应用。通过大量的工程实践和理论研究,人们提出了一种新型钢纤维结构形式——上下层布式钢纤维混凝土(Layer SteelFiber Reinforced Concrete 简称LSFRC),它是将少量的钢纤维均匀撒布于路面板的上下两个表层,而中间仍为素混凝土层。LSFRC中的钢纤维一般由人工或机械撒布,钢纤维较长,长径比一般在70~120之间,呈二维分布。在不影响力学性能的条件下,这种材料大大降低了钢纤维的用量,同时也避免了整体式纤维混凝土在搅拌时易出现纤维结团现象。此外,钢纤维在混凝土中的层布位置对混凝土的抗折强度影响很大,层布在混凝土底部增强效果最佳,随钢纤维层布位置上移,其增强效果明显减弱。LSFRC比同配合比的素混凝土抗折强度提高35%以上,比整体式钢纤维混凝土略低,但LSFRC可节约大量材料成本,也不存在搅拌难的问题。因此,LSFRC是一种具有良好社会经济效益和广阔应用前景的新材料,值得在路面施工中推广应用。 3. The type of steel fiber reinforced concrete layer cloth. Monolithic fiber concrete because its not easy to mix, dosage of fiber cluster, larger issues, cost is higher, affect its widespread application. Through a large number of engineering practice and theoretical research, people put forward a new steel fiber structure form, the lower level of cloth type steel fiber Reinforced Concrete (Layer SteelFiber Reinforced Concrete LSFRC), it is a small amount of steel fiber evenly throughout the road plate two up and down surface, and is still the middle plain Concrete floor. LSFRC in general by manual or mechanical spraying steel fiber, steel fiber is longer, the length to diameter ratio is in commonly 70 ~ 120, the two dimensional distribution. Conditions, in does not affect the mechanical properties of the material greatly reduces the dosage of steel fibre, but also avoid the monolithic fiber concrete in the cluster phenomenon is easy to appear when mixing fiber. In addition, the steel fiber concrete in the layer of cloth position had a great influence on the flexural strength of concrete, floor cloth enhancement effect is best at the bottom of the concrete, with steel fiber layer cloth position up, its enhancement effect significantly weakened. LSFRC than with mixing proportion of concrete flexural strength increased by more than 35%, than the integral steel fiber reinforced concrete was only slightly lower, but LSFRC can save a large amount of material cost, also does not exist, the difficulty of mixing. LSFRC, therefore, is a kind of good social economic benefits and broad prospects for application of new materials, is worthy of popularization and application in pavement construction. 4. 层布式混杂纤维混凝土。层布式混杂纤维混凝土(Layer Hybrid Fiber Reinforced Concrete,简称LHFRC)是在LSFRC基础上掺入0.1%的聚丙烯纤维,把大量细而短,具有较高抗拉强度、高极限延伸率的聚丙烯纤维均匀分布在上、下层钢纤维混凝土和中间层的素混凝土中形成的复合材料。它可以克服LSFRC中间素混凝土层比较薄弱的缺点,防止表层钢纤维磨出后存在的安全隐患。LHFRC可明显增强混凝土的抗折强度,与素混凝土相比,其对素混凝土的抗折强度提高20%左右,与LSFRC相比,其抗折强度提高2.6%,但对混凝土的抗折弹性模量影响不大,LHFRC的抗折弹性模量比素混凝土的高1.3%,比LSFRC的低0.3%。LHFRC还可明显增强混凝土的弯曲韧性,其弯曲韧性指数是素混凝土的8倍左右,是LSFRC的1.3倍。而且由于LHFRC中两种或多种纤维在混凝土中的表现不同,可以根据工程需要,利用合成纤维、钢纤维在混凝土中的正混杂效应,大幅度提高材料的延性、耐久性、韧性、抗裂强度、抗折强度、抗拉强度等,改善材料质量和延长材料使用寿命。 4. Layer cloth type hybrid fiber concrete. Cloth type Hybrid Fiber Concrete Layer (Layer Hybrid Fiber Reinforced Concrete, LHFRC) is on the basis of LSFRC mixed with 0.1% of polypropylene Fiber, put a large amount of fine, short, has a high tensile strength, high limit elongation polypropylene Fiber evenly distributed, the lower steel Fiber Concrete, and the middle tier on plain Concrete in the formation of the composite materials. It can get rid of disadvantages of LSFRC middle plain concrete layer is weak, to prevent surface after grinding out the security hidden danger of steel fiber. LHFRC can obviously enhance the flexural strength of concrete, compared with plain concrete, the flexural strength of plain concrete increase about 20%, compared with LSFRC, the flexural strength increased by 2.6%, but the impact is not big on the flexural modulus of elasticity of concrete, the LHFRC flexural elastic modulus is 1.3% higher than plain concrete, 0.3% lower than that of LSFRC. LHFRC still can obviously enhance the flexural toughness of concrete, the flexural toughness index is about 8 times of plain concrete, is 1.3 times of LSFRC. And because the LHFRC in two or more fiber in the concrete performance is different, can according to the needs of engineering, the use of synthetic fiber, steel fiber concrete in the positive hybrid effect, increase the ductility of the material, durability and toughness, crack resistance strength, flexural strength, tensile strength, such as improving material quality and prolong service life.

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