沈阳宝能环球金融中心C70大体积自密实混凝土关键制备技术与性能研究

Study on key preparation techniques and performance of C70 self-compacting concrete for Baoneng Global Financial Center

结合沈阳宝能环球金融中心C70大体积自密实混凝土施工及技术要求,进行配合比设计与性能研究。研究结果表明:I级粉煤灰减水效果最明显的取代掺量在15%~20%之间,此掺量范围内可减水约7%;利用I级粉煤灰与硅灰制备出性能优异的C70大体积自密实混凝土,坍落扩展度710 mm,倒坍时间3.2 s,U型箱高度差0,利于泵送,坍落扩展度与J环扩展度之差0,离析率5.9%,其高抛免振捣性能优良;降低水泥用量,能够显著降低胶凝材料体系的水化速率与收缩,胶凝材料体系绝热最高温度仅为63.5℃,且水化速率慢,7 d收缩率为1.5×10-4,对于提升混凝土的体积稳定性是有利的,粉煤灰的微集料效应进一步提升混凝土的密实度,其抗冻性能与抗渗性能大大提高;扫描电镜(SEM)结果显示,适当加入矿物掺合料,可增加混凝土结构密实性,提高抗压与抗渗性能。

Combined with the C70 self-compacting concrete construction and technical requirements of Baoneng Global Financial Center,the mix design design and properties of C70 self compacting concrete is studied.The results show that the most obvious substitution effect of Grade I fly ash is between 15%and 20%,and the water content can be reduced by about 7%within this range.Grade I fly ash and silica fume excellent performance of C70 self-compacting concrete,slump expansion of 710 mm,collapse time 3.2 s,U-box height difference of 0,which is conducive to pumping,slump expansion and J ring expansion of the difference 0,the resolution of 5.9%,its high throwing vibration performance.To reduce the amount of cement can significantly reduce the hydration rate and shrinkage of the cement material system,the highest temperature of cement material system adiabatic only 63.5℃,and the hydration rate is slow,7 d shrinkage rate of 1.5×10-4,is conducive to improving the volume stability of concrete,fly ash micro-aggregate effect to improve the density of concrete,its frost resistance and impermeability greatly improved.SEM results show that pressure and impermeability of concrete structures can be increased by the appropriate addition of mineral admixture.