基于气体渗透性的混凝土材料耐久性能研究

发布时间：2018-03-17 13:06

  本文选题：混凝土　切入点：气体渗透性　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：多数混凝土耐久性问题是由于有害物质通过混凝土内部孔隙侵蚀混凝土内部造成的,因此,外界物质穿透混凝土的能力,即渗透性,对于评估混凝土的耐久性有重要的意义。本文通过配制不同配比的混凝土试件,测试了水胶比、粉煤灰含量对混凝土气体渗透性的影响,探讨了混凝土气体渗透性的测试影响因素;分析了混凝土孔隙率、孔隙表面积、孔径大小与混凝土气体渗透性的关系;研究了水胶比、粉煤灰含量对于混凝土碳化性能的影响,探索了混凝土碳化性能与气体渗透性的相互关系;研究了高温作用和应力荷载对混凝土气体渗透性的影响。主要得出以下结论:混凝土试件的气体渗透性在5.78×10-18-1.90×10-17m2之间,属于低渗透性介质;当粉煤灰含量在0%和30%之间,混凝土的气体渗透性随粉煤灰含量的增大而逐渐减小,而当水胶比在0.35到0.55之间,混凝土的气体渗透性随水胶比的减小而逐渐减小;混凝土的孔隙率随水胶比的增大,而不断变大,随粉煤灰含量的增加而稍微减小;BET表面积随着水胶比的逐渐增大,先增大后略微减小,随着粉煤灰含量的增大,BET表面积逐渐增大;水胶比和粉煤灰含量均对混凝土最可几直径没有明显影响;孔隙率和孔隙直径对混凝土气体渗透性影响较小,相反混凝土孔隙的挠曲度对混凝土气体渗透性有重要影响;混凝土碳化深度随着碳化时间增长而逐渐加深,且碳化速度逐渐变缓;对于粉煤灰含量30%的混凝土,水胶比越小,混凝土的碳化深度越小;对于水胶比0.45的混凝土,粉煤灰的含量越高,混凝土的碳化深度就越大;相比混凝土气体渗透性,混凝土的碳化性能受碱性物质含量的影响更大;以60℃为基准,在200℃、350℃、500℃温度作用下,混凝土的气体渗透性分别提高了3.8、11.7和72.6倍;高温作用使混凝土气体渗透性对围压更为敏感,k12MPa/k3MPa由0.87降低至0.41;混凝土的气体渗透性,在轴向荷载小于0.6P时,随着轴向荷载的逐渐增加保持稳定或者略微下降,在0.7P之后略微增大,并在0.8P时增速加快。
[Abstract]:Most concrete durability problems are caused by harmful substances eroding the concrete interior through the internal pores of the concrete, so the ability of the external material to penetrate the concrete, that is, the permeability, It is of great significance to evaluate the durability of concrete. In this paper, the effects of water binder ratio and fly ash content on the permeability of concrete are tested. The influence factors of concrete gas permeability testing, the relationship between porosity, pore surface area, pore size and permeability of concrete are discussed, and the effects of water binder ratio and fly ash content on the carbonation performance of concrete are studied. The relationship between carbonation property and gas permeability of concrete is explored, and the effect of high temperature and stress load on gas permeability of concrete is studied. The main conclusions are as follows: the gas permeability of concrete specimen is between 5.78 脳 10-18-1.90 脳 10-17m2. When the content of fly ash is between 0% and 30%, the gas permeability of concrete decreases with the increase of the content of fly ash, but when the water-binder ratio is between 0.35 and 0.55, The gas permeability of concrete decreases with the decrease of water-binder ratio, and the porosity of concrete increases with the increase of water-binder ratio, and decreases slightly with the increase of fly ash content, and the surface area of BET increases with the increase of water-binder ratio. With the increase of fly ash content, the surface area of BET increases gradually, the water / binder ratio and fly ash content have no significant effect on the maximum allowable diameter of concrete, and the porosity and pore diameter have little effect on the permeability of concrete gas. On the contrary, the deflection of concrete pore has an important effect on the gas permeability of concrete; the carbonation depth of concrete gradually deepens with the increase of carbonation time, and the carbonation rate gradually slows down; for the concrete with 30% fly ash content, the water-binder ratio is smaller, The lower the carbonation depth of concrete is, the higher the content of fly ash is, the greater the carbonation depth of concrete is when the water-binder ratio is 0.45. Compared with the gas permeability of concrete, the carbonation performance of concrete is more affected by the content of alkaline substance. On the basis of 60 鈩，

本文编号：1624867