高温前后钢纤维轻骨料混凝土断裂能研究

用陶砂、陶粒轻骨料部分或全部替换普通细骨料与粗骨料,并掺入0.2%体积掺量的PP纤维,设计0与1%两种钢纤维轻骨料混凝土.以25、200、400、600℃四种温度变化、两种不同骨料种类混凝土基体为研究对象.通过三点弯曲断裂试验得到荷载-挠度曲线,对高温前后钢纤维轻骨料混凝土断裂能进行研究.研究结果表明:1%体积钢纤维掺量能有效减缓裂缝的形成并限制其扩展,大幅度提升了轻骨料混凝土延性与变形能力,从而显著提高断裂能.随着温度的升高,轻骨料混凝土表现出假塑性的破坏特征.在25~400℃作用范围内,混凝土试件的断裂能呈现随温度上升而逐渐增大趋势,但是600℃作用后,断裂能呈现下降现象.

Experimental study on fracture energy of steel fiber lightweight aggregate concrete before and after high temperature

Ceramic sand and ceramsite lightweight aggregate are used to partly or totally replace ordinary fine aggregate and coarse aggregate,design of lightweight aggregate concrete with 0 and 1%steel fibers.Four kinds of temperature change and two kinds of different aggregate concrete matrix were designed at 25,200,400 and 600℃.The load-deflection curve was obtained by three-point bending fracture test.The fracture energy of steel fiber lightweight aggregate concrete before and after high temperature was studied.The results show that 1%volume steel fiber can effectively slow down the formation of cracks and limit their expansion.,and thus significantly improves the fracture energy.With the increase of temperature,lightweight aggregate concrete shows characteristics of pseudoplastic failure.The fracture energy of concrete specimens increases gradually with the increase of temperature in the range of 25~400℃,but decreases after 600℃.