溶液气压法测试混凝土的抗渗性能
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摘要
实际工程中的混凝土结构,因侵蚀性介质的存在而使非力学破坏行为无处不在,这些非力学破坏行为包括碱集料反应、硫酸盐侵蚀、碳化、钢筋锈蚀、冻融等,单一的破坏形式或多形式的复合破坏作用对混凝土结构性能及耐久性能均有着较为严重的影响,在很大程度上缩短了建筑物的服役年限,而这些非力学破坏在很大程度上取决于其渗透性,所以测试混凝土渗透性能是研究判断混凝土耐久性的常规必测项目。
     目前许多学者在研究混凝土渗透性能测试方式上最常选用的是快速氯离子渗透实验方法(ASTMC1202)和电导方法。这两种方法在测试过程中常因发生极化反应、溶液温度升高、孔溶液的化学成分等影响因素而使测试结果有所偏差。同时也有些学者认为通电量与氯离子迁移并没有直接联系,也就是说ASTMC1202方法与电导法与氯离子渗透深度之间的相关性较差。传统的氯离子渗透浸泡法测试周期较长,而国标GBJ82-85方法测试工作繁重、效率很低,所以这两种方法也很少被采用。溶液气压法是在上述方法之上进行改进提高的,克服了国标GBJ82-85方法中的许多不足之处,能够多角度、快速、高效、真实、准确地再现现场混凝土的渗透情况,并且能间接反映碱-骨料反应、钢筋锈蚀、碳化、硫酸盐侵蚀及冻融破坏的影响,对混凝土耐久性的监测与研究具有重要意义。
     在设计方案中,采用对比样同时成型、同时养护、同时测试,以减小差异;选择水灰比在0.26-0.60之间,压力范围在0-4MPa之间,覆盖可测试区间;测试加压渗透过程中混凝土的电导率,描述渗透过程。
     本课题的主要技术路线是:采取溶液法、GBJ82-85、ASTMC1202,三种方法同时对比混凝土、砂浆的渗透性能实验,探明了溶液气压法与国标的相关性,其相关系数在0.9728-0.9913之间。可代替国标GBJ82-85使用。
     另一方面,我们利用混凝土所固有的性质:不同水灰比混凝土、砂浆、抗渗性能规律;不同龄期混凝土的抗渗规律;不同外加剂、掺合料抗渗性能之间相互对比规律;不同黏度渗透液物理化学吸附对测试结果影响的规律;用规律来映证溶液气压法的科学性,准确性。由于溶液气压法的测试,而使得混凝土的渗透性能规律了解的更为清晰,不同混凝土间的对比关系更为准确有效,更定量化。
For concrete structure in the practical engineering, the non-mechanics damages, such as alkali-aggregate reaction, sulfate attack, carbonization, steel rust, freeze and thaw, and so on, are unavoidable due to the exist of erosive media. The deterioration form of mono or multi-factor influences on the concrete property of construction and durability greatly, and shortens the service life of the concrete to a large extent. Permeability of concrete is the most important factor for these non-mechanics damages, so the permeability test of concrete is the normal and required item to study the durability of concrete.
    Now many scholar most and often choose the Quick Cl- permeability test (ASTM C 1202) method to study the permeability of concrete. But the results of these two methods deviate unavoidably from the actual data due to the polarization, generating heat, the chemical composition of the pore solution, and so on during the process of the test. At the same time, some scholars consider that there is no direct relativity between the electricity and the chloride migration, as well between ASTM C 1202 and Electric conductivity. And the traditional immersion method and GBJ82-85 are applied less due to the long test period, heavy and lower efficiency respectively. The liquid-gas method is improved based on the above methods, overcoming the defects of GBJ82-85. Using the liquid-gas method, permeability condition of concrete can be tested and indicated quickly, efficiently, and the influences on concrete of alkali-aggregate reaction, sulfate attack, carbonization, steel rust, freeze and thaw can be inflected indirectly. It
     is significant on the research and monitor on the durability of concrete.
    In the experiment design, comparison samples are modeled, cured and tested at one time for reducing deviation, and w/c are choosed from 0.6 to 0.26, test pressure frome 0 to 4MPa for covering test area. The conductivity of concrete is tested during the permeability to describe permeability process in detail.
    The main technique route of this study is that by the methods of liquid-gas method, GBJ82-85 and ASTMC1202, concrete and mortar permeability are tested at one time. The method correlates with GBJ82-85 very well, and the relative coefficient is 0.9728-0.9913. The method can replace of GBJ82-85.
    On the other hand, through inhibted performances of concrete and mortar, the permeability refutations with different w/c, ages, admixture, and physics chemistry absorb regulation of different viscosity permeable liquid, the liquid-gas method is
    
    
    
    proved science and accuracy. Because adopting with liquid-gas method it case clearer concrete permeability regulation. Different concretes relativity is more exact and more efficiency and fixed quantity.
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