Investigation On Mechanics Performance Of Material And Shearing Performance Of Flexural Member Of Recycled Concrete

Along with urbanization accelerating gradually in our country, the excessive demand of natural sandstone and the mass production of waste concrete have brought great pressure to both environmental and social. recycled concrete (RAC) technology put forward In this background, which has now become one of the hot spot of the development of concrete materials,can solve the above problems effectively, has been researched on in many countries all over the world, and will be applied widely gradually. To promote RAC technology furtherly, expand the application scope of RAC technology, two aspects such as mechanics performance of material and shearing performance of flexural member of RAC are researched respectively in this paper.1.Through the test of material mechanics performance of RAC, the differences of material mechanical performances of RAC which has different sources of recycled coarse aggregate, such as cubic compressive strength, prism compressive strength, splitting tensile strength and bond anchoring strength, and the effect of different recycled coarse aggregate replacement ratio and different mineral admixtures on material mechanical performances of RAC, such as cubic compressive strength, prism compressive strength, splitting tensile strength and bond anchoring strength, are studied. Then, conclusions are drawn as follow:(1)The effect of recycled coarse aggregate replacement ratio on cubic compressive strength of RAC is more significant, while the effect of sources of recycled coarse aggregate on cubic compressive strength of RAC is not obvious; replacement ratio of recycled coarse aggregate and mineral admixtures are two important factors which affect the prism compressive strength of RAC; while the effect of sources of recycled coarse aggregate on prism compressive strength of RAC is minimum; mineral admixtures are the most important factor which affect the splitting tensile strength of recycled coarse aggregate, while the effect of sources of recycled coarse aggregate on the splitting tensile strength of RAC is not obvious; steel grade is the most important factor which affect the maximum average bond strength of RAC, followed by recycled coarse aggregate replacement rate, the effect of the bar diameter and mineral admixtures are not significant.(2)Overall, mechanical properties of RAC decrease as recycled coarse aggregate increase. However, when the replacement rate of recycled coarse aggregate is 50%, the cubic compressive strength and maximum average bond strength both increase instead, even more than ordinary concrete.2.Through the tests of shearing performances of flexural members of RAC, the differences of shearing performances of flexural member of RAC which has different sources of recycled coarse aggregate, and the effect of different recycled coarse aggregate replacement ratio and different mineral admixtures on shearing performances of flexural member of RAC are studied. Then, conclusions are drawn as follow:(1)As the replacement ratio of recycled coarse aggregate increase, the number of cracks of beam of RAC increases exponentially; the numbers of cracks of beams of RAC which has different sources of recycled coarse aggregate are closer; fly ash furtherly promote the development of cracks.(2)The replacement ratio of recycled coarse aggregate, sources of recycled coarse aggregate and fly ash all have a greater and roughly the same impact on the crack load of RAC beam; the replacement ratio of recycled coarse aggregate have a greater effect on the ultimate load of RAC beam, while the effect of sources of recycled coarse aggregate and fly ash is not great.(3)The cracking load and the ultimate load of RAC beam are both lowerer than normal concrete, and decrease as the replacement ratio of recycled coarse aggregate increases. Added into fly ash, the cracking load and the ultimate load both decrease.Finally, the effect of recycled coarse aggregate replacement rate on shear capacity of beam of RAC is also analyzed in the paper. Combined with the existing "Design of Concrete Structures", through regression analysis of test data, the formula of shearing strength of CRC beam under concentrated loads is established. Upon examination, the calculation values and the experimental data are closer. Thus, the formula can be used as reference for future research.