转体PC斜拉桥混凝土构件的力学性能研究

Study on Mechanical Properties of Concrete Members of Rotational PC Cable-stayed Bridge

为了提高PC斜拉桥混凝土构件的力学性能,共设计了18组替代率及水灰比不尽相同再生砖粉浆体的混凝土试件,研究了水灰比和再生砖粉浆体替代率对混凝土试件破坏特征、应力-应变曲线和单轴抗压强度的影响。结果表明,再生砖粉主要由SiO_(2)、Al_(2)O_(3)、Fe_(2)O_(3)和CaO组成,经过过筛后呈不规则形状。低水灰比条件下,再生砖粉混凝土试件呈现脆性破坏特征,在较高的水灰比条件下,再生砖粉混凝土试件呈韧性断裂特征。在相同水灰比条件下,再生砖粉浆体替代率的升高会增加28 d单轴抗压强度。再生砖粉浆体的添加,可以在混凝土制备过程中与水泥等发生水化反应而形成C-S-H等用于填充混凝土的间隙,且再生砖粉浆体替代率的增加,密实度提高的同时可以抵抗更大的外加应力。

In order to improve the mechanical properties of concrete members of PC cable-stayed bridges,a total of 18 groups of concrete specimens with different replacement ratios of recycled brick powder were designed;the effects of water-cement ratio and replacement ratio of recycled brick powder on the failure morphology,stress-strain curve,and uniaxial compressive strength of concrete specimens were studied.The results show that the recycled brick powder is mainly composed of SiO_(2),Al_(2)O_(3),Fe_(2)O_(3),and CaO,and after sieving,it presents an irregular shape.Under low water-cement ratio conditions,recycled brick powder concrete specimens exhibit brittle failure characteristics,while increasing the water-cement ratio,the failure mode of recycled brick powder concrete specimens changes to ductile failure.Under the same replacement ratio of recycled brick powder paste,the uniaxial compressive strength of recycled brick powder concrete specimens gradually decreases as the water-cement ratio increases from 0.35 to 0.55.Under the same water-cement ratio,an increase in the replacement ratio of recycled brick powder paste will increase the 28 d uniaxial compressive strength.The addition of recycled brick powder paste can cause hydration reactions with cement during the preparation of concrete to form gaps such as C-S-H that can be used to fill the concrete.Moreover,with the increase in the replacement rate of recycled brick powder paste,the compactness can be improved while resisting greater external stress.