Standardization of Method for Determination of Material Composition Ratio of Fresh Concrete

(1)本研究建立的试验方法可以通过氯化钠浓度折射仪和重力仪的联合使用，快速、简便、准确地估计新拌混凝土(水、水泥、骨料和空气)的组成比。由于在估算新拌混凝土单位用水量时，必须从有效用水量中剔除水泥上的吸水量，因此对单位用水量进行了定量测定。配制了测定水泥悬浮液比重的水样溶液，将4L水与2L含氯酸钠溶液200g的新鲜混凝土试件混合，浓度为单位水的25%。(2)通过对预拌混凝土厂的质量控制体系的广泛调查，得知新拌混凝土在拌和后的期望配合比的差异很难被检查。(3)这种方法对预拌混凝土厂或施工现场的混凝土质量的提高和稳定是有用的，但在任何情况下，它都必须被认为是用于试验的批处理混凝土的抽样。(4)这种方法适用于具有特殊性能的高强混凝土。由于期望配合比稍有不同就会影响混凝土的性能，因此适用于此类混凝土的质量控制。

(1) It is possible for the test method established in this studies to estimate rapidly, simply and accurately the quantity ratio of composition of fresh concrete (water, cement, aggregates and air) through joint use of a concentration refractometer of chloride sodium and a gravimeter. As the amount of absorption water on cement must be excluded from the effective water to estimate the unit water of fresh concrete, it was determined quantitatively. The sample solution to measure the specific gravity of cement suspension was prepared to mix 4l of water with 2l of the fresh concrete sample contained 200g of chlolide sodium solution with 25% of concentration for measure of unit water. The volume of air in fresh concrete was measured with the test by pressure method from another sample.(2) As result of extensive investigation of the quality control system in ready-mixed concrete plants, it was known that the difference of mixing ratio of fresh concrete for expectation was hardly checked after the mixture.(3) This method is useful for an advancement and stability of quality of concrete at a ready-mixed concrete plant or at a job site of construction, but in all cases it is must be considered the sampling of batch concrete for the test.(4) This method applies to high strength concrete with particular properties. As a little difference for expected mixing ratio influences the properties, it is suitable for the quality control of such a concrete.