混合梁斜拉桥钢—混结合段混凝土的配制与性能研究

Study of Preparation and Performance of Concrete Used in Steel-Concrete Joint Section of Hybrid Girder Cable-Stayed Bridge

为满足混合梁斜拉桥钢-混结合段填充混凝土的自密实、低收缩和高韧性的特殊要求,以九江长江公路大桥为背景,制备C55普通自密实混凝土、微膨胀聚丙烯纤维自密实混凝土和微膨胀钢纤维自密实混凝土,对其工作性能、力学性能、弯曲韧性、塑性收缩开裂性能、限制膨胀率和抗氯离子渗透性进行试验研究。结果表明,与普通自密实混凝土相比,优选出的微膨胀钢纤维自密实混凝土不仅满足自密实工作性能的要求,而且显著提高了混凝土的弯拉强度、劈拉强度和弯曲韧性,大幅度提高了抑制塑性收缩开裂的能力,并具有一定的微膨胀特性,能满足钢-混结合段混凝土的特殊要求。

In order to meet the special demands of self consolidating, low shrinkage and high ductility of concrete filled in the steel-concrete joint section of hybrid girder cable-stayed bridge, against the background of Jiujiang Changjiang River Highway Bridge, the C55 grade average self- consolidating concrete, micro-expansion polypropylene fiber self-consolidating concrete and mi- cro-expansion steel fiber self-consolidating concrete were prepared, and the corresponding experi- mental study was carried out to analyze the working performance, mechanical behavior, flexural stiffness, plastic shrinkage cracking, limited expansion rate and chloride resistant property of these three types of concrete. The results of the study show that, compared with average self- consolidating concrete, the selected micro-expansion steel fiber self-consolidating concrete not on- ly meets the working performance requirements of self-consolidating concrete, but also improves the flexural tensile strength, splitting tensile strength and flexural stiffness of concrete, and en- hance the ability of inhibiting plastic shrinkage cracking of concrete to a great extent. The micro expansion steel fiber self-consolidating concrete has some micro-expansion capacity which can meet the special demands of concrete used in steel-concrete joint section.