利用高石粉机制砂制备C80超高强钢管混凝土及其性能研究

Study on preparation and properties of C80 ultra-high strength concrete with machine-made sand of high stone powder

针对利用高石粉机制砂制备C80超高强钢管混凝土过程中易出现浆体黏度大、流动性差、收缩变形大等问题,选用低引气、超分散降黏和高保塑功能的功能型外加剂、掺加高水化活性的粉煤灰微珠+硅灰复合矿物掺和料和高能延迟膨胀剂,并通过配合比优化设计,制备出C80超高强钢管混凝土初始坍落度/扩展度为240/615 mm,2 h后坍落度/扩展度量损失低于20 mm,28 d抗压强度达到100.8 MPa,含气量为2.0%,90 d自由膨胀率稳定于3.45×10^(-4)。研究成果成功应用于湖北恩施某高速公路特大钢管拱桥,经检测混凝土强度、脱空率均满足设计要求,应用效果良好。

Considering the poor flowability and large shrinkage in the preparation of C80 ultra-high strength self compacting concrete filled steel tube with machine-made sand with high stone powder content,through the optimization of the mixture ratio,and by using polycarboxylate superplasticizer with low air entraining,ultra dispersion viscosity reduction and high plasticity,and high hydration activity mineral admixtures of fly ash beads+silica fume,C80 ultra-high strength self compacting concrete filled steel tube with the initial slump/dispersion of 240/615 mm and the slump/dispersion losses after 2 h less than 20 mm,28 d compressive strength reaching 100.8 MPa,the air content of 2%,the free expansion rate of 90 d in the sealed curing condition stably at 3.45×10-4.The research results have been successfully applied to a super large steel tube arch bridge of a highway in Enshi,Hubei Province.After testing,the strength and void ratio of concrete meets the design requirements,and the application effect is good.