Research and Application of Shrinkage-compensating Self-compacting Concrete for Steel Box Structure
In order to meet the pouring requirements of C50 self compacting(SC)micro-expansive concrete in the spherical hinge of swivel support and the left and right turntables of Anjiazhuang grand bridge of the new line of na-tional highway 109,the workability of concrete was maintained for more than 4 hours by compound high robust super long slump reducing agent and mix proportion optimization.The reducing agent is composed of multiple compo-nents,including high robust slow-release E-type mother liquor,water reducing mother liquor,slump retaining mother liquor,setting time regulator and state regulator,which is the key measure to maintain the super long work-ability of self-compacting concrete(SCC);Adding 5％silica fume into the cementitious system of cement+mineral powder+fly ash+expansive agent can not only improve the rheological properties of concrete to reduce the shear strain and speed up the flow rate,which is conducive for SCC,but also make the slurry structure more stable,re-duce the segregation and bleeding phenomenon to improve the strength and durability of concrete after setting and hardening;According to the requirements of slump retention,cement and aggregate are preferred.The mix propor-tion is optimized from the perspective of improving the overall grading,which further improves the super long reten-tion performance of SCC workability.The SCC has been successfully applied to the Anjiazhuang super large bridge project of national highway 109,which provides a powerful technical guarantee for the early capping.The prepara-tion and application of SCC with ultra long workability maintenance provides an effective solution for engineering construction in remote areas requiring long-distance transportation and special technical requirements,as well as similar projects.
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