早期受力对再生混凝土孔隙结构及力学性能研究

Study on Pore Structure and Mechanical Properties of Recycled Concrete Under Early Stress

为了缓解废弃混凝土对生态环境造成的压力,减少废弃混凝土对生态环境的不利影响,使用粗骨料全替代制备了再生混凝土,并探究了早期受力对后期性能的影响。将制备好的混凝土养护至定龄期(1d、3d、7d、14d)后对其压载(定龄期极限荷载的20%、40%、60%、80%),通过测其抗压强度、劈裂强度及微观孔隙结构分析,得出混凝土试块早龄期(1d、3d)施加预压荷载,将其养护至28d时抗压强度几乎不受影响;当加载小于极限荷载的60%时,其抗压强度下降幅度较小,当加载超过极限荷载的60%,对混凝土内部造成不可逆的损伤,会导致混凝土的抗压强度下降速度加快;加载后的试块其劈裂强度均受到了影响,其强度均低于未压荷载的试块强度,且当加压荷载一定时,随着养护至定龄期时间的增加,劈裂强度越低,微观孔隙结构分析印证了对其力学性能的分析。

In order to alleviate the pressure of waste concrete on the ecological environment and reduce the adverse impact of waste concrete on the ecological environment,the recycled concrete was prepared by using the total replacement of coarse aggregate,and the influence of early stress on the later performance was explored.In order to explore the influence of early stress on later performance,the prepared concrete was cured to a fixed age(1d,3d,7d,14d)and then ballasted(20%,40%,60%,80%of the limit load of the fixed age).By measuring its compressive strength,splitting strength and micro-pore structure analysis,it was concluded that the compressive strength of the concrete test block was almost unaffected when it was cured to 28d under preloading load at early age(1d,3d).When the loading is less than 60%of the ultimate load,the compressive strength decreases slightly.When the loading exceeds 60%of the ultimate load,irreversible damage is caused to the interior of the concrete,which will lead to an accelerated decrease in the compressive strength of the concrete.The splitting strength of the test block after loading is affected,and its strength is lower than that of the test block without compressive load.When the compressive load is constant,the splitting strength decreases with the increase of curing time to a certain age.The micro-pore structure analysis confirms the analysis of its mechanical properties.