Influence Of Mineral Admixtures On Chloride Binding Capacity Of Concrete

Chlorine ion binding properties of concrete can be of great significance for reinforced concrete durability. The chloride ions who exist as the presence of bound form are no harm to concrete reinforcement corrosion. It delayed the diffusion rate of chlorine ions, extending the life of reinforced concrete structures. In this paper, based on different ways and principles that chloride ions binding in, we studied how these factors which include the mineral admixtures species, dosage and adding way, the chloride ion concentration and the p H value of the erosion environment affect the Chlorine ion binding properties of concrete. The main contents and results are as follows:After analysis and comparison of the titration, potentiometric titration, ion selective electrode method merits of concrete chloride ion concentration measurements, and the choice of ion-selective method as the measurement of chloride ion concentration method of the present experiment. Because of the selection of the chloride ion selective electrode response p H range is small, when using a conventional method, measuring the acid-soluble chloride ion concentration of p H can not meet the response problem, the thesis of measurements made some improvements.After testing measuring and verification, the improved sche me can satisfy the test requirements.The effects of different content, the single with fly ash, slag, fly ash and slag and binding properties of chlorine ions concrete. Found that fly ash and slag can greatly improve the concrete case of the chloride ion binding capacity, and the same content, and enhance the role of the former than the latter; the main mechanism to improve respectively are physical adsorption and chemical bonding effect.Studied erosion environments chlorine ion concentration of chloride ion binding properties of concrete. Found that the chloride ion concentration, can promote AFm phase to a process Friedel salt hydrates can also increase the amount of physical CSH gel adsorbed chloride ions. However, due to a certain amount of binding agent can be combined with a certain amount of chloride ions, with chloride ion concentration, although the amount of chlorine ions bound concrete has increased, but the chloride ion binding capacity will decline.Studied the influence of p H on chloride etchant concrete binding capacity. Found that erosion p H value increases, not only can hinder AFm phase Friedel salt into the process, can reduce the physical adsorption capacity of CSH gel hydration products of chlorine ions. However, the experimental group w ho mixed mineral admixture, when the etchant p H value exceeds a certain value, p H value is increased to promote the secondary hydration of mineral admixtures, thus improving chloride ion binding capacity...