SGER: An Exploratory Study of a Test Device for Concrete Permeability

混凝土是民用基础设施中应用最广泛的材料。混凝土的劣化是一个世界性的大问题。影响混凝土结构耐久性的一个重要因素是混凝土的渗透性。低渗透性减少了水分和侵蚀性物质进入混凝土，从而为钢筋提供了更好的保护，并限制了混凝土因冻融而变质。然而，由于缺乏合适的测试方法和设备，混凝土的渗透性并没有作为质量评估和控制的手段进行常规测量。在最近的一项研究中，PI和他的同事构思了一种创新的方法，通过使用一种简单而经济的测试设备来测量混凝土的渗透性。该方法利用轴对称表面气流模型确定混凝土渗透系数。他们的工作为这一概念提供了证据，并证明了该测试装置能够对不同年龄、不同水灰比的混凝土进行一致的测量。他们还证实，空气在离混凝土表面半英寸的范围内流动是可以实现的。此外，他们还发现，渗透率指数与快速氯化物渗透率试验结果和90天积水试验中的氯化物渗透率之间存在令人满意的相关性。本探索性研究的目的是进一步发展和完善测试方法和设备。更具体地说，研究将解决四个关键问题：(1)确定混凝土含水率对透气性的影响；(2)探索将混凝土表面干燥到足够深度以消除含水率影响的技术；(3)改进试验装置以增加空气进入混凝土的深度；(4)在现场建立适当的混凝土表面准备程序，使试验装置能够成功应用

Concrete is the most widely used material for the civil infrastructure.Deterioration of concrete is a major worldwide problem. An important factor thataffects the durability of concrete structure is the permeability of concrete. Lowpermeability reduces the entry of moisture and aggressive substances into concrete, thus provides better protection for the steel reinforcement and limits deterioration of concrete due to freezing-thawing. However, for lack of a suitable test method and device, the permeability of concrete is not routinely measured as a means of quality assessment and control.In a recent study, the PI and his co-worker conceived an innovative method tomeasure concrete permeability by using a simple and economical test device. The method makes use of an axi-symmetric surface air flow model to determine the concrete permeability index. Their work provided the proof of the concept and demonstrated that the test device was capable of making consistent measurements for concrete with different water-cement ratios at different ages. They also verified that air flow within one-half inch from the concrete surface was achievable. In addition, they found satisfactory correlations between the permeability index with the results of rapid chloride permeability tests and chloride penetrations from 90-day ponding tests.The objectives of this exploratory research are to further develop and refine thetest method and device. More specifically, the research will address four critical issues: (1) determine the effect of the moisture content of concrete on permeability, (2) explore techniques to dry the concrete surface to a sufficient depth to eliminate the effect of moisture content, (3) improve the test device so as to increase the depth of air flow into the concrete, and (4) establish an appropriate procedure for the concrete surface preparation in the field so that the test device can be applied successfully