沪通长江大桥水下自密实混凝土工作性能试验研究

通过流动性试验、间隙通过性试验、流变性能试验和灰色关联度分析,研究了胶凝材料用量、水胶比、砂率、粉煤灰掺量等因素对水下自密实混凝土工作性能的影响。试验结果表明:当水胶比在0. 36～0. 38,胶凝材料用量在440～480 kg/m3,砂率为50%,粉煤灰掺量在35%～45%时,混凝土的屈服应力和塑性黏度较小,流动性及间隙通过性较为优异,综合分析确定了最优的混凝土配合比;胶凝材料用量和水胶比是影响混凝土工作性能的主要因素,而砂率和粉煤灰掺量对混凝土工作性能的影响相对较小;混凝土流动性对V形漏斗流出时间最为敏感,对坍落扩展时间和倒置坍落度筒排空时间的敏感性差别不大;提出了低胶凝材料用量、高体积稳定性的水下自密实混凝土制备方法,为沪通长江大桥及同类超大深水基础复杂结构工程水下自密实混凝土的制备提供了试验和理论依据。

Experimental Research on Working Performance of Underwater Self-compacting Concrete for Shanghai-Nantong Yangtze River Bridge

The effect of different factors such as water binder ratio,cementitious binder content,sand ratio,and fly ash content on the working performance of underwater self-compacting concrete was studied through f luidity experiment,clearance trafficability test,rheological property test and grey relevance degree analysis.Results show that the yield stress and plastic viscosity of concrete are relatively small and the f luidity and clearance traff icability of concrete are excellent when water binder ratio ranges from 0.36 to 0.38,the cementitious binder content ranges from 440 kg/m^3 to 480 kg/m^3,sand ratio is 50%and fly ash content ranges from 35% to 45%,and the optimum concrete mix proportion is determined by comprehensive analysis.The cementitious binder content and water binder ratio are the major factors inf luencing the working performance of concrete,whereas sand ratio and fly ash content have relatively minor effect on the working performance of concrete.The concrete fluidity is most sensitive to outf low time of V-shaped funnel,there is no signif icant difference in sensitivity between slump spreading time and emptying time of inverted slump cone.The preparation method of underwater self-compacting concrete with low cementitious material content and high volume stability was put forward,which provides experimental and theoretical basis for the preparation technology of underwater self-compacting concrete in Shanghai-Nantong Yangtze River Bridge and similar super-large deep water foundation complex structure projects.