Experimental Study On Eccentric Compressive Behaviors Of Frost-resistant Recycled Aggregate Concrete Column

Frost resistance is a significant part of the concrete durability, as for recycled aggregate concrete, also received high attention in this aspect. Lots of study have been done around the world about the material performance of recycled aggregate concrete under freezing and thawing cycles. In order to make further study, the experiment of frost-resistant recycled aggregate concrete structure under freeze-thaw cycle will be a better choice.In this paper, 18 columns of frost resistance concrete with recycled aggregate were made to find out how the properties of the columns go with the ratio of recycled aggregate and frost-thaw cycle times. At the same time, 9 prism specimens were made. During the frost-thaw cycles, the weight and dynamic modulus of specimens will be measured to work out the rate of weight loss and relative dynamic modulus. According to these two index, we can find out the frost level of the environment test.According to the frost-thaw cycle experiment, some conclusions were found. As the ratio of recycled aggregate and frost-thaw cycle times increase, the rate of weight loss and relative dynamic modulus increase in the early stage, and then become to descent. The peak value of the rate of weight loss and relative dynamic modulus are 0.77% and 5.4%, which means the frost resistance of the recycled aggregate concrete is pretty gold.According to the result of the static experiment of column, some conclusions can be drew. Firstly, when the ratio of the aggregate replacement and cycle times grow up, the cube compressive strength values of frost resistance recycled aggregate concrete will descend. As for columns, their bearing capacity will also descend as the increase of these two factors. Secondly, according the comparison for different columns, this conclusion were found that columns with 50 mm eccentricity presented small eccentric damage mode, while the others which had 100 mm eccentricity presented big eccentric damage mode or over-reinforced damage mode. We also find out the change rules of failure made influenced by frost-thaw cycle times and the ratio of recycled aggregate. Otherwise, the experiment result confirmed that frost resistance recycled aggregate concrete column meet the flat section assumption.Numerical methods are used to calculate the theoretical value of columns. According to the result, we can find that ordinary concrete specification can be used to design frost resistance recycled aggregate concrete columns. Otherwise, if the constitutive relation of frost resistance concrete is used, the theoretical value will little smaller than the former, it mean this theory is much more conservative, but it means more safe in some aspects.