再生骨料取代率及老砂浆强度对混凝土细观性能的影响

Effect of recycled aggregate replacement ratio and old mortar strength on mesoscopic properties of concrete

建立6种不同再生骨料取代率细观数值模型,基于基面力元法研究单轴压缩荷载作用下5种不同再生老砂浆强度对混凝土内部微裂纹的扩展及单轴抗压强度的影响.研究表明:基于势能原理的基面力元法可以推导荷载作用下混凝土等非均质材料的单元应变及单元刚度矩阵;单轴压缩荷载作用下,再生混凝土的抗压强度随着再生骨料取代率的增加而递减、随着老砂浆强度的提高而递增;当取代率小于40%,老新砂浆强度比大于0.80时,老砂浆强度能显著提高单轴抗压强度;内部微裂纹首先出现在新老黏结带,然后穿过粗骨料密集区域形成连续破坏裂缝,裂缝宽度随着取代率的增加而增加,随着老砂浆强度的增加而减小。

Six different recycled aggregate replacement ratios of concrete was established,and then five different parameters of adhered mortar strength were simulated to research the internal cracks and compression strength based Base Force Element Method(BFEM).The simulation results show that BFEM can be used to derive the element strain and element stiffness matrix of heterogeneity materials,such as concrete.The compression strength decreases with increasing the recycled aggregate replacement ratios.While,the compression strength increases with the old mortar strength and the compression strength increases.Further,when the replacement ratios is less than 40%and the strength ratio between old mortar and new mortar is less than 0.80,the old mortar has a significant influence on the compression strength.As for the crack,the internal cracks are formed in the new and old interfacial transition zones,and then expansion into continued crack around the aggregates.In addition,the width of the continuous crack is increased with the replacement ratios increase and decreased with the old mortar strength increases.