【作者】 赵丽华；

【导师】 陈静云； 王生武；

【作者基本信息】 大连理工大学 ， 市政工程， 2013， 博士

【摘要】 我国沥青路面大修周期较短,提高沥青路面的服务质量和使用寿命是目前研究工作的重点。研究人员从改善材料的基本性能入手进行了大量研究,其中添加纤维改善沥青混合料性能以其效果明显和施工易行得到了普遍认可。玄武岩纤维在沥青混合料中应用时间较短,是一种新型的矿物纤维。其强度高,模量大,耐高温、不老化、化学性质稳定,具有较大的开发潜力和广泛的工程应用前景。本文结合玄武岩纤维性能、纤维沥青胶浆性能、纤维沥青混合料性能、纤维沥青混合料断口宏、细观形貌特征及玄武岩纤维沥青混合料低温黏弹性,分析了玄武岩纤维对沥青混合料性能的改善效果及机理。本文主要工作如下：1、玄武岩纤维性能研究系统开展了玄武岩纤维耐高温性、吸湿性、与沥青的黏附性、耐酸碱性、灰分含量、吸油率的试验测试,并应用扫描电镜对玄武岩纤维的细观形貌进行分析,全面评价了用于热拌沥青混合料的玄武岩纤维性能。借鉴复合材料广义混合率理论,研究了玄武岩纤维的质量分数对沥青胶浆黏度的影响,证明弱相支撑黏度理论的适用性,阐明玄武岩纤维有增黏效果。2、玄武岩纤维对沥青混合料性能影响研究通过纤维沥青混合料的高温稳定性、低温抗裂性、水稳定性、断裂能、疲劳性能、蠕变性能等室内试验,定量评价两种不同形态的玄武岩纤维对AC-16C型沥青混合料路用性能的改善效果,并分析玄武岩纤维对沥青混合料性能的改善机理。研究结果表明,玄武岩纤维棉(CBF纤维)能显著提高沥青混合料路用性能,短切玄武岩纤维丝(SCBF纤维)除对沥青混合料水稳定性改善效果不良外,对其他性能均呈现明显的增强效果。结合纤维沥青混合料的性能及机理分析,证实玄武岩纤维的pH值及其与沥青黏附性对改善沥青混合料性能具有重要影响,建议我国规范增加相应技术指标要求。3、玄武岩纤维沥青混合料断口宏、细观形貌分析采用断口形貌学的分析方法,对沥青混合料试件断口宏、细观形貌特征进行分析,讨论了沥青混合料力学性能与断口形貌的关系,进一步分析了玄武岩纤维增强沥青混合料力学性能的改善机理。宏观断口分析研究表明,掺加玄武岩纤维后,沥青混合料内部空洞减少,提高了集料断口、界面脱胶断口的比例,从而提高了沥青混合料的抗裂性能。细观分析证实,玄武岩纤维为亲油性材料；在沥青混合料中,纤维搭接于微裂纹两侧,改善了局部缺陷,增强了整体性。SCBF纤维在混合料中分散不均,有局部成团现象,可能因沥青裹附不足而成为试件的薄弱环节,从而影响混合料的整体强度和稳定性。分析玄武岩纤维在沥青混合料断口处的形貌特征,本文提出了“强度薄弱区”的概念,认为在纤维与沥青黏结界面区和自由沥青之间存在着不稳定的沥青层,当外力产生的拉应力方向与纤维方向相同时,纤维将从该强度薄弱区拔出。4、玄武岩纤维沥青混合料黏弹性及数值模拟分析基于沥青混合料常温及低温条件下的弯曲蠕变试验,通过数据拟合获得了适合玄武岩纤维沥青混合料的蠕变模型参数,证明模型的适用性,并揭示了玄武岩纤维改善沥青混合料低温抗裂性能的机理。采用时间硬化模型,实现了ABAQUS软件对小梁弯曲蠕变试验的数值模拟分析。更多还原

【Abstract】 In our country, overhaul period of asphalt pavement is frequently short, thus the improvement of service quality and usable life of the asphalt surface is the focus of the research at present. Researchers have done a lot of work to improve the basic properties of material, and now it is widely accepted that adding fiber can improve the performance of asphalt mixture for its effectivity and convenience.Basalt fiber is a new mineral fiber type that not for prolonged use in asphalt mixture. With high strength, big modulus, high-temperature tolerance, anti-aging and chemical stability, basalt fiber has great development potential and wide engineering application prospect. In the thesis, effect and mechanism of basalt fiber in improving the performance of asphalt mixture was analyzed by basalt fiber properties, fiber-asphalt mortar performance, fiber-asphalt mixture performance, macroscopic and microscopic fracture morphology characteristics and low-temperature viscoelasticity of basalt fiber asphalt mixture.This thesis comprises the following sections:1. Basalt fiber performance research A systematic experimental study was conducted to investigate the performance of basalt fiber which included high temperature resistance, hygroscopicity, adhesion properties to asphalt, acid and alkaline resistance, ash content, oil absorption rate and microscopic morphology analysis by scanning electron microscopy (SEM). The results provided a comprehensive evaluation on performance of the fiber adding to asphalt mixture. Based on the generalized mixture rule theory of composite material, we studied the influence of basalt fiber mass fraction to asphalt mortar viscosity, proved the applicability of the viscosity theory of weak phase support, clarified that the basalt fiber had reinforced adhesion effect.2. Effect of basalt fiber on asphalt mixture performanceBased on the laboratory tests of high temperature stability, low temperature crack resistance, water stability, fatigue and creep properties and so on, a quantitative evaluation of the performance improvement of two different basalt fiber forms in AC-16c asphalt mixture had been done and the improving mechanism of basalt fiber to the asphalt mixture was analyzed. The results proved that the cotton basalt fiber (CBF fiber) was able to improve the pavement performance significantly; short-cut basalt fiber (SCBF fiber) showed remarkable enhancement effect on all asphalt mixture properties excepting water stability. Combined with the analysis of fiber asphalt mixture performance and mechanism, we confirmed that PH value and asphalt adhesiveness of basalt fiber had an important effect on improving the performance of asphalt mixture. Therefore, we suggest that the corresponding technical index requirements should be added to the specification.3. Basalt fiber asphalt mixture fracture morphology analysisBy fractography analysis method, the appearance characteristics of asphalt mixture fracture were analyzed. We also discussed the relationship of mechanical properties and fracture morphology and analyzed the improvement mechanism of the basalt fiber on reinforcing asphalt mixture mechanical property further more.The study of macroscopic fractography showed that the inner cavity of asphalt mixture reduced while the aggregate fracture proportion and interface deboning fracture both increased after adding basalt fiber. Therefore, we can conclude that basalt fiber improves the crack resistance of asphalt mixture. The research of microscopic fractography showed that basalt fiber was lipophilic material. Fiber linking the micro crack restricted local defects and enhanced the integrity. SCBF fiber dispersed unevenly in the mixture, observed as parts-clustering phenomenon, which might become the weak point of the specimen due to the insufficient of asphalt coating, and then affected the overall strength and mixture stability.The conception of "mechanical weakness region" was proposed in this thesis by the analysis of the morphology features of basalt fiber in the asphalt mixture fracture. We considered that there was an unstable asphalt interlayer between the fiber-asphalt interface and free asphalt. Fiber would be pulled out from this region when the direction of stress generated by force and the fiber orientation were the same4. Basalt fiber asphalt mixture viscoelasticity and numerical simulation analysisBased on flexure creep test of asphalt mixture at both room temperature and low temperature conditions, the creep model parameters that suited fiber asphalt mixture were obtained by data fitting. It proved the applicability of the model, while it also indicated the mechanism how basalt fiber improve anti-cracking performance of asphalt mixture at low temperature. With time hardening model, we obtained the numerical simulation analysis of beam bending creep test on ABAQUS software.更多还原