Experimental Research On Creep Behavior Of Recycled Concrete Based On Pretreatment Of Recycled Coarse Aggregate

Facing with the grim situation because of the shortage of natural resources such as sand, stone etc, and the increase of construction wastes, promote the reuse of the old concrete will become an important way to solve the issue of waste concrete. It is a fundamental solution to the waste concrete problem because it can help achieve economic and social benefits. The currently recycled concrete research mainly focused on the basic mechanical properties of recycled concrete, but it’s creep characteristics is rare reported. Due to the characteristics of the recycled aggregate are different from the natural aggregate, recycled concrete creep performance has a big difference from ordinary concrete. This paper mainly focuses on the creep performance of recycled concrete. The main work and conclusions are listed as follows:1.The influence of different recycled coarse aggregates replacement rates and different recycled aggregate strengthen treatment processes (pre-wet, steep liquor wrapped stone craft and incorporation of silica fume steep liquor wrapped stone craft) have on the basic mechanical properties of recycled concrete were analyzed by basic mechanical performance experiments. The results showed that with the increase of recycled coarse aggregate replacement rate, the cube compressive strength and elasticity modulus of recycled concrete showed different degrees of lower. The strengthen pretreatment processes we used in this test turned out to be useful methods to improve the mechanical properties of recycled concrete. Among them incorporation of silica fume steep liquor wrapped stone craft turned out to be the best one and the next was pre-wet, and the last was steep liquor wrapped stone craft.2.By uniaxial compressing creep experimental researches on the unsealed and sealed concrete specimens. The influence of different recycled coarse aggregate replacement rates have respectively on the total creep and basic creep performance of recycled concrete were analyzed and compared with normal concrete. The results showed that the increase of recycled coarse aggregate replacement rate would lead to remarkable increase of total creep and basic creep deformation of recycled concrete.3.Base on the research of different recycled coarse aggregate replacement rates, the influence of different recycled aggregate strengthen treatment processes have respectively on the creep performance of recycled concrete under compression were analyzed. The results showed that the three recycled aggregate strengthen treatment processes mentioned above could reduce creep deformation of recycled concrete remarkably. Among them incorporation of silica fume steep liquor wrapped stone craft turned out to be the best one and the next was steep liquor wrapped stone craft.4.After analyzing the creep values got from the experiment and compared them with those calculated from several widely-used models which exist domestically or abroad, an appropriate ACI model was selected as a reference and some appropriate parameters can be introduced to the original ACI model according to the results generated by the experiment. As a consequence, a suitable model to predict the creep of recycled concrete can be acquired.