Mix Granulated Substance In Pump Concrete Applied Research

The artificial sand as a new kind of construction-use sands, has been widely used in construction industry to get better economical benefit and social benefit, and its applications are gradual abroad. The considerable achievements have been obtained in the studies of production process, technical performance and application in concrete and mortar of crushed stone fines from 1960s in our country. The crushed stone fines now have a wide application in concrete engineering, such as hydraulic and hydroelectric engineering, but the application in pumping concrete is started later.The applied technology of sand mixed with crushed stone fines and superfine sand in the pumping concrete is researched on the basis of experiments in this article. The main contents including:1. Some experiments are done to compare the effects of crushed stone fines, natural medium sand and mixed sand on the technical performance of pumping concrete. The results indicated that, the slump of concrete with crushed stone fines is the lowest, the slump of concrete with natural medium sand is higher and the slump of concrete with mixed sand is high. And the crushed stone fines should not be used in the pumping concrete separately. The concrete compressive strength of 7 days and 28 days is the highest of the concrete with crushed stone fines, is lower of concrete with mixed sand and is the lowest of concrete with natural medium sand. The carbonation resistance of concrete is the best of concrete with mixed sand, is good of concrete with natural medium sand and is worse of concrete with crushed stone fines. The impermeability is almost the same in three kinds of concrete.2. The theoretical analysis and some experiments are done to determine the rational incorporating proportion of crushed stone fines and superfine sand in mixed sand. The interval of theoretical value of the rational incorporating proportion of crushed stone fines is calculated, based on the requirements of fineness modulus and grain gradation of fine aggregate in pumping concrete. A assumed completely filled principle is proposed according to the definition of rational sand rate. A theoretical calculating formula to calculate the rational replacement level of crushed stone fines in mixed sand is obtained according to this principle. The experiment results are in good agreement with the theoretical calculation. The result that the rational replacement level of crushed stone fines in mixed sand is 70% is finally determined.3. A fine aggregate coefficientβis introduced in the Bolomey formula to show the influences of the incorporating proportion of crushed stone fines in mixed sand on strength of concrete. The Bolomey formula for concrete with mixed sand is obtained by the regressive analysis of test data.4. From the viewpoint of economy, the mix ratio of concrete with mixed sand is optimum designed by the Matlab GA Tool.A more economical result is obtained. The economic cost of this mix ratio is 9.07yuan less than the mix ratio we have used per cubic meter of concrete.