Concrete filled steel tube and preparation method thereof

The invention discloses a concrete filled steel tube and a preparation method thereof, relates to the technical field of concrete, and solves the technical problem of shrinkage cracking and even void of the concrete filled steel tube in the prior art. Per cubic meter of the concrete contains 550-580 kg of Portland cement, 40-45 kg of fly ash, 45-50 kg of silica fume, 950-980 kg of gravel, 700-720 kg of sand, 38-45 kg of a composite internal curing agent, 15-22 kg of a composite expanding agent, 5-6 kg of a polycarboxylic acid water reducing agent and 155-165 kg of water. The composite internal curing agent is a mixture of red water permeable brick particles and shale ceramsite, and the composite expanding agent is a mixture of magnesium oxide and calcium oxide. The concrete filled steel tube provided by the invention has the advantages of high anti-cracking grade and small shrinkage rate. 本发明公开了一种钢管混凝土及其制备方法，涉及混凝土技术领域，解决现有技术中钢管混凝土收缩开裂甚至脱空的技术问题，每立方米所述混凝土中含有以下质量的原材料：硅酸盐水泥550-580kg，粉煤灰40-45kg，硅灰45-50kg，碎石950-980