Study On Permeability And Dissolved-erosion Of Dam Concrete Material

More attention has been drawn from the professional and the public towards the endurance of concrete structure nowadays, among which the abilities of permeability and erosion are the main factors to be estimated to determine the endurance of concrete constructions. This article is based on the theoretical discussion and previous experiment records, a permeability test of concrete material has been carried out as well, however, the experimental conditions are modified and improved in order to reflect the real work state of the material in which the permeability of concrete is considered under the effect of various factors and interactions among them. The analysis subject used in dissolved-erosion experiment is the original material from engineering instances. Major aims for such experiment are to reveal the interaction process between dam concrete and surrounding water, and meanwhile, to build an analogical model of liquid-solid processing status for the quantitative analysis using the basic principles of chemic-thermodynamics.The reliability of analysis result depends largely on the in-house experimental conditions. Unlike the previous analysis that only concerns the sole effect of permeable pressure, this article considers both permeable and confining pressure and deformation characteristics of concrete material under the interaction of them according to the real work state of construction, which may leads to the changing pattern of permeable rate as listed below: permeable rate (PR) always reaches its peak with the time process going on, than goes down and remains straight on some certain value; The PR will tend to decline while the confining pressure is increased, and the time taken before the peak will be extended as well; Under the constant permeable pressure and circularly changing confining pressure, the minus-exponential ascend and descend relationship could be applied between the PR and Time axes respectively with crannied and intact concrete samples, and the PR of crannied concrete is far more larger than that of intact concrete. The change pattern of concrete could also be mathematically analogized using the least square method.The dissolved-erosion experiment of liquid - concrete material is using the newand old samples of Xin'anjiang reservoir water soaked original on-site concrete. During the analysis of the above-mentioned process, four representative indexes are measured to give an overall estimation of dissolve-erode conditions of samples, namely, separated concentration of Ca(OH)2, pH value, TDS and conductance. The exact changing scenario of these factors are as follow: the separated concentration of Ca(OH)2 increased quickly at the beginning, then gradually slowed down and closed to the saturation at the last; TDS and conductance indexes were increased with time process; The phenomenon of pH values varied obviously among the samples may be explained by the differences of assort rate, ages, weathering grade factors, etc. exist between the new and old concrete samples. At last, based on the chemic-thermodynamics saturation index model and after appropriate calculation, the conclusion of reactions between the liquid solution and solid medium at different times has been drawn to the end of this report.