The invention discloses concrete of a strength grade C220 for a steel
reinforced concrete combined structure. The concrete comprises
cement, fine aggregate, coarse aggregate, water, a water
reducing agent, a defoaming agent,
silicon powder,
coal ash, an excitant, an expanding agent and a composite plastic retaining agent in a ratio of 488:742:1262:97.6:19.7:1.2:96:120:10:50:0.50. A preparation method comprises the following steps: firstly, uniformly mixing the water
reducing agent, the excitant and the composite plastic retaining agent with water so as to obtain a mixture, sequentially adding the fine aggregate, the coarse aggregate and 1 / 3 of the mixture into a stirrer according to a weight ratio, adding the coarse aggregate and 1 / 3 of the mixture, uniformly mixing, adding the
cement, the expanding agent, the
silicon ash and the
coal ash, uniformly mixing, adding the defoaming agent and the rest mixture, stirring, and discharging, thereby obtaining the concrete. By adopting the concrete, the bonding property of steel and concrete can be remarkably improved in a
natural state, respective mechanical properties and mutual synergetic working properties of the steel and the concrete can be effectively taken into play, the bearing property, the use performance and the durability of a
structural component can be greatly improved, and good volume stability and economy can be achieved.