Research On Long-term Behavior And Creep Characteristics Of Expansive Concrete

Expansive concrete is a kind of special concrete. Mixing the expanding agent into the concrete can generate some dilatant which can make the concrete expande by the cement hydration. The expansion can compensate the shrinkage of the concrete or creat initial stress. With the development of the expanding agent, the number of the concrete mixed with different kinds of expand agent increases and the application of the expansive concrete becomes more and more comprehensive. But there are still some problems during the process of the expansive concrete's application. In allusion to the pop problems about the development of the expansive concrete this paper selects the conventional expansive concrete and investigates its long-term behaviour, durability and the creep character by the experiment. The main research contents and results are as follows:Firstly, the author selects UEA, AEA and MgO as stuff and mixes them into the concrete separately. According to the test specification the author investigates the basic mechanical property, the long-term behaviour, and durability of the different kind of expansive concretes. Comparing with the general concrete the author gets the conclusions. Under the condition of free expansion the compression strength, the carbonization resistance, the impermeability, frost resistance and the bar rust resistance of the concrete mixed with UEA or AEA are all worse than concrete without expansive agent. Compare with the UEA, AEA expansive concrete the MgO expansive concrete whose frost resistance and the bar rust resistance even are better than general concrete expresses relatively good performance. The same to the general concrete the expansive concrete may shrink if there is no properate curing. Mixing expansive agent into the concrete can increase its confined expansion ratio effectively. The conclusion is that the expansive concrete must be used under proper confinement condition so that it can display the potency.Secondly, according to the problem of the delayed ettringite formation in mass concrete the author reads a lot of argumentative academic reports and gets the conclusion by test. The delayed ettringite may format in the mass concrete and the decomposition temperature of the delayed ettringite is 80℃. The prophase curing is very important. If the water can be impeded to enter into the mass concrete that the delayed ettringite formation may avoides. As well as controlling the inner temperature of the mass concrete can avoid the damage caused by the delayed ettringite formation effectively. At last, the creep of expansive concrete is researched and the creep character is plotted. According to the test data, the author gets proper expansive concrete creep models by Curve Fitting supplied by ANSYSY and gives the suggestions about how to select expansive concrete element when calculate with ANSYS.