商品混凝土质量控制技术（Control technology of concrete quality goods）.docVIP

商品混凝土质量控制技术（Control technology of concrete quality goods） At present, the majority of concrete used in building engineering is commodity concrete, and it needs to meet the pumping requirements. According to the characteristics of commodity concrete, this paper discusses the quality control technology of commercial concrete. Raw material control 1, cement: Ordinary portland cement in general is appropriate. The pump should be used in commercial concrete Portland cement, ordinary portland cement, slag Portland cement and Portland fly-ash cement, not by volcano gray Portland cement, because it needs much water, easy bleeding. Pump commodity concrete cement more dosage, strength grade C20~C60 range of cement dosage is 350~550Kg/M3. The quality control of cement must be strict, and the quality certificate shall be used when the goods are purchased. According to the cement dosage, showed that a large number of domestic and foreign research and practice, a number of high-quality fly ash into concrete, not only can replace part of cement, but also because the fly ash particles were spherical with strong ball effect, lubrication, can improve the fluidity and viscosity of concrete mixture of poly and the water. 2, fine aggregate: fine aggregate should use medium, coarse sand. Pump concrete should be used in the sand and by the upper limit, 0.315mm sieve sieve margin should not be less than 15%. Practice has proved that the fineness modulus of 2.8 sand fineness modulus compared with 2.3 in the sand, the water consumption can be reduced 20~25Kg/m3, can reduce the dosage of cement 28~35Kg/m3, thus reducing the heat of hydration of cement, reduce the concrete temperature and contraction. The fine aggregate mud content is less than 3%, clod content shall not be greater than 1%. Other quality indicators shall be in line with the current industry standards, quality standards and test methods for ordinary concrete sand. In order to ensure the fluidity, cohesiveness and water retentio