The invention discloses concrete for the steel
reinforced concrete composite structure C250 strength grade. The matching ratio of
cement to fine aggregate to coarse aggregate to water to water
reducing agent to antifoaming agent to silica
powder to
coal ash to exciting agent to expanding agent to composite plastic retaining agent is 504:769:1,308:102:21:1.5:100:125:11:52:0.65. A preparing method includes the steps that the water
reducing agent, the exciting agent and the composite plastic retaining agent are evenly stirred into water to obtain a mixture, and the fine aggregate and 1 / 3 of the total mixture are sequentially added into a stirring
machine according to the weight ratio and stirred to be even; the coarse aggregate and 1 / 3 of the total mixture are added and stirred to be even; the
cement, the expanding agent, the silica
powder and the
coal ash are added and stirred to be even; the antifoaming agent and the residual mixture are added, and the mixture is stirred and discharged. By means of the concrete, the bonding performance between structural steel and the concrete can be remarkably improved under the
natural state, the mechanical performance and the
cooperative work performance of the steel and the concrete are effectively developed, the
carrying capacity, the use performance and the durability of a
structural element are greatly improved, and the concrete has the good high volume stability and the good economy.