寒区海洋环境下高性能混凝土桥梁配合比研究

Study on Mix Proportion of High Performance Concrete Bridge in Marine Environment at Cold Region

随着区域经济社会的持续发展,沿海地区长大跨度桥梁建设日益增多。为了解决目前海洋寒冷环境下高性能混凝土配合比设计存在的不足,基于全计算法对高性能混凝土配合比设计方法进行了优化。首先理论分析了全计算法在计算高性能混凝土配合比时存在的问题,并针对全计算法中水胶比公式提出了修正。然后通过设计多组对照试验,指出了寒冷地区海洋环境下采用标准全计算法配制的高性能混凝土存在的缺点,并通过配合比试验对改进全计算法的有效性进行了验证。结果表明:(1)在对照试验下,运用标准全计算法得出的高性能混凝土配合比能够满足抗冻、抗渗和碳化要求,但存在砂率和水胶比偏大的问题,因此针对水胶比公式提出了修正系数γ;(2)在综合考虑混凝土抗压强度、胶凝材料总量和混凝土耐久性试验后,验证了修正后的全计算法的有效性,并指出修正系数的建议取值范围为0.85~0.925,其中修正系数越小,水胶比越小,抗碳化能力和抗氯离子侵蚀能力越高;(3)结合工程实例,进一步验证了改进的全计算法得到的高性能混凝土配合比满足设计要求,其强度值、抗渗等级、抗冻性能等参数均满足指标要求。研究成果拓展了全计算法理论在寒区海洋复杂环境中的应用,为实现我国桥梁建设向迈入深海提供一定的技术支撑。

With the continuous development of regional economy and society, the construction of long-span bridges in coastal areas is increasing. In order to solve the shortcomings of high performance concrete mix design in the cold marine environment at present, the high performance concrete mix design method is optimized based on the full calculation method. First, the problems of the full calculation method in calculating the high performance concrete mix proportion are theoretically analyzed, and the formula of water-binder ratio in the total calculation method is revised. Then, by designing multiple sets of control test, the shortcomings of the high performance concrete prepared by the standard full calculation method in the marine environment in cold region are pointed out, and the effectiveness of the improved full calculation method is verified through the ratio test. The result shows that(1) the high performance concrete mix proportion derived by applying the standard full calculation method in the control test can meet the requirements of frost resistance, seepage resistance and carbonation, but there are problems of large sand rate and water-binder ratio, so the correction factor γ is proposed for the water-binder ratio formula;(2) after comprehensively considering the compressive strength of concrete, the total amount of cementitious material and the durability test of concrete, the effectiveness of the modified full calculation method is verified, and it is pointed out that the recommended value range of the correction coefficient is 0.85-0.925, where the smaller the correction coefficient, the smaller the water-binder ratio and the higher the resistance to carbonation and chloride ion erosion;(3) combining with engineering examples, it is further verified that the high performance concrete mix proportion obtained by the improved full calculation method meets the design requirements, its strength value, impermeability grade, frost resistance and other parameters all meet the indicator requirements. The research result expands the application of the full calculation method theory in the cold marine complex environment, and provides some technical support for the bridge construction in China to step into the deep sea.