C55机制砂混凝土在桥梁主梁的应用研究

发布时间：2018-04-13 13:08

本文选题：石粉 + 机制砂　；参考：《重庆交通大学》2014年硕士论文

【摘要】：机制砂代替天然砂是混凝土行业可持续发展的趋势，不仅支持我国基础建设的持续发展，解决部分地区天然砂砂源紧缺的问题，而且对保护生态环境、降低工程成本均有重大的实际价值。首先，本文对机制砂自身特性进行研究，从宏观与微观两方面入手:采用对比相同级配下天然砂与机制砂砂浆性能，研究发现机制砂对强度具有增强效应，但对工作性有负面效应；运用SEM与XRD对石粉进行形貌与成份分析，发现石粉是一种非玻璃体，且破碎卵石与石灰岩的石粉主要成份分别为SiO2和CaCO3；通过内掺与外掺不同石粉含量的水泥净浆流动度试验，结果表明石粉对减水剂有吸附作用，并对水泥水化有加速效应；运用均匀设计研究了机制砂1.18mm以下颗粒含量对机制砂性能及砂浆性能的影响，提出机制砂颗粒级配的关键筛孔为0.6mm。其次，本文以C55机制砂混凝土的配制和性能测试为基础，通过正交设计优选了C55机制砂混凝土配合比的配制参数，并在相同条件下改变混凝土中的细集料，与水洗机制砂、原状机制砂和不同岩性的砂进行对比研究。研究了机制砂对混凝土工作性、力学性能、耐久性及体积变形性的影响，并探讨了机制砂生产不水洗的可行性。试验结果表明:采用水洗机制砂配制的C55高性能混凝土的总开裂面积为320mm2/m2 ，早期抗裂性为IV级，渗等级为P17，56天电通量为461C；原状机制砂石粉含量为6.3%，亚甲蓝为1.0g/kg，其混凝土抗渗性、抗裂性及体积变形性能比水洗机制砂混凝土优，当机制砂石粉的亚甲蓝值为1.0g/kg时，对高强高性能混凝土可适当放宽石粉含量界限到6%；机制砂混凝土的力学性能、抗裂性能及体积变形性能在相同条件下均优于天然砂混凝土，但其抗渗性能不及天然砂混凝土；机制砂仅岩性的改变，对混凝土性能无显著影响，当石粉含量在6%内对机制砂混凝土长期性能无明显影响。最后，通过SEM电镜扫描和显微硬度测试技术，研究发现细集料岩性的改变不会影响混凝土水化产物形貌；石粉具有填充效应和晶核效应；适量的石粉能改善混凝土内部骨料界面过渡区的不均匀性。通过研究，，采用机制砂可配制桥梁主梁用C55高性能混凝土。
[Abstract]:It is the trend of sustainable development of concrete industry to replace natural sand with machine-made sand. It not only supports the sustainable development of infrastructure in China, but also solves the problem of shortage of natural sand source in some areas, and it also protects the ecological environment.It is of great practical value to reduce the project cost.First of all, this paper studies the characteristics of machined sand, starting from macro and micro aspects: by comparing the properties of natural sand and machined mortar with the same gradation, it is found that the mechanical sand has an enhanced effect on strength.SEM and XRD were used to analyze the morphology and composition of stone powder, and it was found that stone powder is a kind of non-vitreous body.The main components of crushed pebble and limestone are SiO2 and CaCO3 respectively. Through the flow test of cement paste with and without different content of stone powder, the results show that the stone powder can adsorb water reducer and accelerate the hydration of cement.The effect of particle content below 1.18mm on the properties of machined sand and mortar was studied by uniform design. The key sieve hole of grain gradation of machined sand was 0.6mm.Secondly, on the basis of the compounding and performance testing of C55 mechanism sand concrete, the compounding parameters of C55 mechanism sand concrete are selected by orthogonal design, and the fine aggregate in concrete is changed under the same conditions, and the washing mechanism sand is changed under the same conditions.A comparative study was carried out between the undisturbed sand and the sand of different lithology.The effects of machine-made sand on workability, mechanical properties, durability and volume deformation of concrete were studied, and the feasibility of unwashed production of machine-made sand was discussed.The test results show that the total cracking area of C55 high performance concrete prepared by washing mechanism sand is 320mm2/m2.The early crack resistance is grade IV, the permeation grade is P1756-day electric flux is 461C, the content of raw mechanism sand and stone powder is 6.3, methylene blue is 1.0 g / kg, the impermeability, crack resistance and volume deformation of concrete are better than that of water-washed sand concrete.When the methylene blue value of machined sand powder is 1.0g/kg, the limit of stone powder content can be relaxed to 6 for high strength and high performance concrete, and the mechanical properties, crack resistance and volume deformation properties of machined sand concrete are better than that of natural sand concrete under the same conditions.However, its impermeability is not as good as that of natural sand concrete, but only the change of lithology of machined sand has no significant effect on the concrete performance, and when the content of stone powder is within 6%, it has no obvious effect on the long-term performance of machined sand concrete.Finally, by means of SEM scanning electron microscope and microhardness test, it is found that the change of lithology of fine aggregate will not affect the morphology of hydration products of concrete, and the stone powder has filling effect and nucleation effect.Proper amount of stone powder can improve the heterogeneity of the interfacial transition zone of concrete aggregate.Through the research, the C 55 high performance concrete for bridge main girder can be made by using machined sand.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U444

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