机制砂混凝土早龄期热膨胀系数研究

发布时间：2018-04-12 07:07

本文选题：机制砂 + 石粉　；参考：《福州大学》2013年硕士论文

【摘要】：混凝土结构时常发生早期开裂的现象,这会影响混凝土结构的安全及使用寿命。对机制砂混凝土早龄期热膨胀系数进行研究,这对预防机制砂混凝土早期开裂,延长混凝土结构使用寿命具有重要意义。使用Imagepro Plus软件分析机制砂和石粉的颗粒形状。考虑石粉作用,采用等浆体体积法和最少浆体理论,设计机制砂混凝土配合比。通过变化机制砂类型和石粉掺量,研究了机制砂混凝土的力学性能、工作性能、早龄期孔隙率和孔径分布。采用自主研发设计的混凝土早龄期热膨胀系数测量装置,对机制砂混凝土早龄期热膨胀系数进行了研究。主要得到以下结论：1、依据自行建立的机制砂和石粉颗粒形状评价体系,发现采用的机制砂和天然砂颗粒形状有较大差别：机制砂中长条形颗粒比天然砂的多,颗粒棱角比天然砂的多；在粒径大于0.6mm的砂粒中,和机制砂相比,天然砂中圆形颗粒相对较多；在粒径小于0.6mm的砂粒中,天然砂颗粒形状多为方形,而机制砂颗粒形状多为方形和三角形。本文研究的三种石粉大多数颗粒形状均接近圆形,当石粉颗粒粒径较小时,方形颗粒数量有所增多,颗粒棱角也增多。2、自主研发设计了机制砂混凝土早龄期热膨胀系数测量装置。采用波纹管作为模具和采取“快速变温法”,有效减少了混凝土早龄期其他收缩(如自收缩、干燥收缩等)对变形测量的影响。采取自主发明的“悬吊法”,减少了摩擦、扰动对试验的影响。3、机制砂混凝土1d的热膨胀系数与1d抗压强度呈现较好的线性关系,抗压强度越大,热膨胀系数越大。1d孔隙率和1d热膨胀系数也呈现较好的线性关系,孔隙率越大,热膨胀系数越小,验证了热膨胀系数受孔隙率影响的机理解释。4、机制砂混凝土早龄期热膨胀系数随着石灰石粉、硅质石灰岩石粉掺量增大而增大,随着凝灰岩石粉掺量增大热膨胀系数变化不明显。石粉的种类及掺量会对混凝土孔隙率产生影响,进而影响混凝土热膨胀系数。但总体而言,机制砂混凝土早龄期热膨胀系数受石粉种类及掺量影响较小。此外,机制砂混凝土热膨胀系数受机制砂热膨胀系数影响,机制砂热膨胀系数越大,混凝土热膨胀系数也更大。5、采用1stopt软件对机制砂混凝上早龄期热膨胀系数试验数据进行拟合,效果较好,得到了考虑龄期、石粉掺量、细骨料热膨胀系数影响的混凝土早龄期热膨胀系数计算公式。
[Abstract]:Concrete structure often occurs early cracking phenomenon, which will affect the safety and service life of concrete structure. The mechanism of sand concrete early age thermal expansion coefficient of the prevention mechanism of sand concrete early cracking, prolong the service life of concrete structures is of great significance. The mechanism of sand and powder particle shape analysis using Imagepro Plus software. Considering the effect of the powder, paste volume method and least paste theory, mechanism design of concrete mix. By changing the type and mechanism of sand sand powder dosage, studied the mechanism of sand concrete mechanical performance, work performance, early age of porosity and pore size distribution. By using the self-designed device for measuring coefficient of early concrete the age of thermal expansion, the mechanism of sand concrete early age thermal expansion coefficient were studied. The main conclusions are as follows: 1. Based on the mechanism of self built and sand Powder particle shape evaluation system, there is a difference in the mechanism of sand and natural sand particle shape: mechanism of sand strip particles than natural sand, natural sand particles than the edges; the particle size is greater than 0.6mm in sand, compared with machine-made sand, relatively large circular particles in natural sand in the grain; size of less than 0.6mm in sand, natural sand particle shape is square, and the mechanism of sand particle shape is square and triangular. Three kinds of powder in this study most of the particles are close to the circular shape, when the powder particle size is small, square particle number increased, particle angularity also increased.2, independent research and design the mechanism of sand concrete device for measuring the thermal expansion coefficient of early age. Corrugated pipe is used as a mold and adopt the "fast varying temperature method, effectively reduce the concrete early age shrinkage and other (such as self shrinkage, dry shrinkage etc.) of the variable Effect of shape measurement. Take independent invention of the "suspension", reduce the friction and disturbance of the test of.3, mechanism of sand concrete 1D thermal expansion coefficient and the compressive strength of 1D showed good linear relationship, the compressive strength increases, a larger thermal expansion coefficient and porosity of.1d 1D also showed a linear thermal expansion coefficient well, the higher the porosity, smaller thermal expansion coefficient, thermal expansion coefficient of the verification mechanism influenced by the porosity interpretation of.4, the mechanism of sand concrete early age thermal expansion coefficient with limestone, siliceous limestone powder content increases with the increase of content of rock powder ash thermal expansion coefficient did not change significantly. The type and dosage of powder will affect the porosity of concrete, thereby affecting the thermal expansion coefficient of concrete. But overall, the mechanism of sand concrete coefficient by powder type and dosage effect of early age thermal expansion. The mechanism, mechanism of sand sand by coefficient of thermal expansion coefficient of thermal expansion of concrete, sand a larger thermal expansion coefficient, thermal expansion coefficient of concrete is greater.5, using 1stOpt software, the mechanism of sand concrete early age thermal expansion coefficient by fitting the experimental data, the effect is good, have to consider the age, powder content, calculation formula of fine aggregate concrete influence coefficient of thermal expansion coefficient of early age thermal expansion.

【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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