纤维素纤维在南水北调中线沙河渡槽高强混凝土中的试验分析

Test Analysis of Cellulose Fiber in High-Strength Concrete of Shahe Aqueduct in the Middle Route of the South-to-North Water Diversion Project

沙河渡槽是南水北调中线保证通水与否的重要控制工程,是目前采用预制工艺的单体自重最大的薄壁预应力输水构件,对构件的抗裂和强度及耐久性存在极高的要求。纤维素纤维是新兴的复合纤维,属于低弹模级材料。可以大幅提高混凝土及砂浆的均质性,有效抑制早期的塑性裂缝和干缩裂缝,同时改善混凝土的抗渗性、抗冻融性及耐火性,最终达到提高混凝土的耐久性。通过现场在混凝土配合比中添加纤维素纤维的试验,验证纤维素纤维对于高强度混凝土性能的影响和改善,挑选适合沙河渡槽预制槽体混凝土的纤维素纤维以及掺量,达到满足设计要求,保证沙河渡槽的工程质量。

The Shahe aqueduct is an important controlling engineering factor to ensure water running in the Middle Route of the South-to-North Water Diversion Project,and it is a thin-walled prestressed conveyance component using the prefabrication with the largest single unit weight,which has a high requirement for the crack resistance and durability of the component.The cellulose fiber is a new composite fiber and a material with low-elastic modulus.The cellulose fiber can increase the homogeneity of the concrete and mortar substantially,inhibit the plastic cracks and shrinkage cracks of the concrete during the early period,improve the impermeability,freeze-thaw resistance,and fire resistance of the concrete,and improve the durability of concrete ultimately.In this paper,the in-situ test of adding the cellulose fiber into the concrete is performed,which verifies the impact and improvement of the cellulose fiber on the performance of high-strength concrete.Additionally,the cellulose fiber and its content are determined to suit the prefabricated tank concrete of the Shahe aqueduct and to meet the design requirements in order to ensure the engineering quality of the Shahe aqueduct project.