Research On Preparation Method And Basic Mechanical Properties Of High Strength Recycled Concrete

Many roads, buildings and structures have been removed due to the reasons of the development of cities, the aging of buildings, and so on. This produces a lot of waste concrete, sand and gravel aggregate of which accounted for more than sixty percent. If we can fully recycle these aggregates, not only to solve a large number of waste concrete, but also to reduce the consumption of natural aggregate for the construction industry, in addition, to reduce ecological damage caused by gravel mining from the source. This will have great significance for saving energy and resources, reducing the burden on the environment and maintaining ecological balance, so the basic mechanical properties of recycled concrete are studied by optimizing the mix ratio of recycled concrete in this paper. The main results of this paper are as follows:1.By the compressive test of 46 groups of cube specimens of 100mm×100mm×100mm, the influence of water cement ratio, the replacement ratio of recycled coarse aggregate and mineral admixture on the compressive strength of recycled concrete is studied. The empirical coefficient of recycled concrete Bolomey formula, the optimal dosage of recycled coarse aggregate, the combination type of mineral admixture and the strengthening mechanism of the interface transition zone are presented.2.By the uniaxial compression test of 15 groups of prism specimens of 150mm×150mm×300mm, the influence of different the replacement ratio of recycled coarse aggregate on the stress-strain curves, elastic modulus, axial compressive strength and peak strain of recycled concrete is analyzed. The results show that the single axial compression stress-strain curves of recycled concrete under different the replacement ratio of recycled coarse aggregate are in good agreement with the rise section of the whole curve, while the falling section is large; the peak strain of recycled concrete is significantly higher than that of ordinary concrete; the elastic modulus of recycled concrete is obviously lower than that of ordinary concrete.3.By the splitting tensile and compressive test of 56 groups of cube specimens of 100mm×100mm×100mm, the effect of steel fiber volume ratio, mineral admixture, and steel fiber types on the tensile and compressive properties of recycled concrete cubes is studied.4.By the bending test of 12 groups of prism specimens of 100mm×100mm×400mm, the influence of steel fiber volume ratio, fiber type on the flexural properties and flexural toughness of recycled concrete is discussed, in addition, we study the mechanism of steel fiber reinforced and toughened.