Study On The Magnesia Concrete Expansion Additive Of Effect

With the development of science technology, one of the most broadly used construction materials is concrete, concrete has been studied and its comprehensive property has also developed and more and more. During the course of hydration, the concrete strength increases companied with the shrinkage distortion, and the tensile/comprehension strength ratio are very low, so it is easy for the concrete to generate crack. In recent years, with the high-strength and high-performance of concrete, extensive use of chemical additive and mineral admixture, the appearance probability of crack in concrete construction increased greatly. Therefore, the prevention and cure of concrete crack has been a focus long investigated in the construction. Now, the most effective way to prevent and reduce the concrete crack is to add proper quantity expansive additive in concrete admixture.Firstly, In the paper, the present studying status and developing tendency of the concrete expansive additive are summarized in the foreign and domestic country. And it is indicated that the applied technology of adding MgO expansive has been successfully used in mass concrete and large dam concrete. The expansive mechanism of three kinds of additives, such as Ettringite, CaO and MgO expansive additive, is introduced in detailed. More than that, the merits and faults of each expansive additive are overviewed. Based on that the concrete shrinkage is a long procedure, it is very necessary to have a kind of new compound additive with double expansive resource, which can satisfy both the requirement of expansive value in early stage and shrinkage compensation in the final stage. Therefore, the influence on the mechanical property, expansive property and developing compatibility of strength is invested when considering adding just magnesia expansive and compound magnesia expansive in common concrete.Secondly, the resource and property parameters of the law materials used in the experiment are introduced. And the main experiment methods, which involved in...