自密实高强混凝土的配制及性能研究

发布时间：2018-10-22 13:38

【摘要】：混凝土自诞生起,因其众多优点逐渐成为使用最广泛的人造材料之一。随着人类建筑技术的不断提高,普通混凝土已经不能满足高层、超高层、超大跨度、不规则结构和复杂工程的需要,因此混凝土的高性能化成为混凝土技术发展方向。高强混凝土相对于普通混凝土具有强度高和耐久性好等诸多优点,研究高强混凝土配制技术,成为混凝土研究的热门方向。伴随着高强混凝土技术的发展及广泛使用,其缺点也逐渐暴露出来,由于高强混凝土采用较多胶凝材料用量,使得混凝土具有较高的粘度、较大的自收缩,从而不利于混凝土浇筑并且具有硬化开裂的风险。因此,研究克服高强混凝土粘度高、自收缩大和浇筑困难等缺点,成为高强混凝土技术发展的重点。结合高强混凝土具有的缺点,本文通过对自密实高强混凝土配制技术、自收缩性能和自养护与耐久性进行研究,配制出自密实、高强、低收缩、自养护和高耐久性混凝土。本文研究的主要结论如下:(1)通过对自密实高强混凝土配制技术研究,复掺粉煤灰和矿粉可以改善混凝土的工作性能和力学性能;在混凝土中掺入5%的硅灰,可以提高混凝土的工作性能和力学性能;通过对水胶比、砂率的研究,配制出的水胶比0.23、砂率44%的自密实高强混凝土具有良好的工作性能和力学性能;优化粗骨料级配可以降低自密实混凝土的粘度,提高工作性能和力学性能。(2)增大水胶比、降低砂率都可以降低混凝土的自收缩。混凝土中掺入粉煤灰可以显著降低混凝土的自收缩,在7d龄期时,掺入10%、20%和30%粉煤灰的混凝土自收缩分别为基准混凝土自收缩的83.9%、72.9%和67.9%。外掺6%、9%和12%膨胀剂的混凝土自收缩相对基准混凝土分别下降了12.9%、41.8%和67.9%。高强混凝土结构密实,混凝土内外部水分交换难度大,传统外界供水养护方法对高强混凝土效果不佳。自养护材料可以降低混凝土自收缩,分别掺入4%水分载体和预湿轻骨料的混凝土自收缩相对基准混凝土7d自收缩分别下降了19.4%和15.3%。(3)掺入2%沸石粉作为自养护材料,可以提高自密实高强混凝土保塑性能,且对28d抗压强度影响不大。试验配制的自养护自密实高强混凝土耐久性良好,掺入沸石粉可以改善自密实高强混凝土的耐久性。试验结果表明沸石粉可以降低混凝土的自收缩,掺入2%沸石粉的混凝土7d自收缩相对基准混凝土下降了17.9%;掺入2%沸石粉的混凝土电通量下降了20.1%;经过150次干湿循环,混凝土抗硫酸盐侵蚀系数由82.4%提高到87.1%;经过28次冻融循环试验,混凝土单位面积剥落物质量下降了29.3%,相对动弹性模量提高了4.9%,说明在混凝土中掺入沸石粉可以提高混凝土的耐久性。
[Abstract]:Since its birth, concrete has gradually become one of the most widely used artificial materials because of its many advantages. With the continuous improvement of human building technology, ordinary concrete can no longer meet the needs of high-rise, super-span, irregular structures and complex engineering, so the high performance of concrete becomes the development direction of concrete technology. Compared with ordinary concrete, high-strength concrete has many advantages, such as high strength and good durability. With the development and wide use of high strength concrete technology, its shortcomings are gradually exposed. Because of the use of more cement materials, high strength concrete has higher viscosity and larger autogenous shrinkage. This is not conducive to concrete pouring and has the risk of hardening and cracking. Therefore, to overcome the shortcomings of high strength concrete, such as high viscosity, large self-shrinkage and difficult pouring, has become the focus of the development of high strength concrete technology. Combined with the shortcomings of high strength concrete, the self-compacting high-strength concrete compounding technology, self-shrinkage performance, self-curing and durability are studied in this paper. The self-compacting, high-strength, low-shrinkage, self-curing and high-durability concrete are prepared by means of self-compacting, high-strength, low-shrinkage, self-curing and high-durability concrete. The main conclusions of this paper are as follows: (1) through the study of self-compacting high-strength concrete preparation technology, the addition of fly ash and mineral powder can improve the working and mechanical properties of concrete, the addition of 5% silica fume into concrete, Through the study of water-binder ratio and sand ratio, the self-compacting high-strength concrete with water-binder ratio of 0.23 and sand ratio of 44% has good working and mechanical properties. Optimization of coarse aggregate gradation can reduce the viscosity of self-compacting concrete and improve its working performance and mechanical properties. (2) increasing water-binder ratio and reducing sand ratio can reduce the self-shrinkage of concrete. Addition of fly ash to concrete can significantly reduce the self-shrinkage of concrete. At 7 days of age, the self-shrinkage of concrete mixed with 10% and 30% fly ash is 83.9% and 67.9% of the standard concrete, respectively. The autogenous shrinkage of concrete mixed with 6% and 12% expansive agent decreased by 12.9% and 67.9%, respectively. The high strength concrete structure is dense, the internal and external water exchange is difficult, the traditional outside water supply and curing method is not good for the high strength concrete. The self-curing material can reduce the self-shrinkage of concrete, and the self-shrinkage of concrete mixed with 4% water carrier and pre-wet lightweight aggregate decreased by 19.4% and 15.33% respectively compared with the reference concrete in 7 days. (3) 2% boiling stone powder was added as the self-curing material. It can improve the plasticity of self-compacting high strength concrete, and has little effect on 28d compressive strength. The self-curing self-compacting high strength concrete has good durability, and the self-compacting high strength concrete can be improved by adding boiling stone powder. The test results show that the autogenous shrinkage of concrete can be reduced by boiling powder, and the autogenous shrinkage of concrete mixed with 2% boiling stone powder in 7 days has decreased by 17.9 relative to the reference concrete, the electric flux of concrete mixed with 2% boiling stone powder has decreased by 20.1. after 150 dry and wet cycles, The sulfate-resistant coefficient of concrete was increased from 82.4% to 87.1%. After 28 freeze-thaw cycle tests, The mass of spalling material per unit area of concrete decreased by 29.3 and the relative dynamic modulus of elasticity increased by 4.9. It shows that adding boiling stone powder into concrete can improve the durability of concrete.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.31

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