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

(1)本研究建立的试验方法通过氯钠浓度折光计和重力仪的联合使用，可以快速、简单、准确地估计新拌混凝土（水、水泥、骨料和空气）组成的数量比。由于估算新拌混凝土的单位水量必须将水泥的吸水量从有效水量中剔除，故对其进行定量测定。制备测量水泥悬浮液比重的样品溶液，将41 l水与21 l含有200g氯化钠溶液，浓度为单位水测量浓度的25%的新混凝土样品混合。用另一试样的压力法测定了新拌混凝土中的空气体积。(2)对预拌混凝土厂的质量控制体系进行了广泛的调查，了解到在混合后，新拌混凝土的预期配合比差很难检查。(3)本方法对预拌混凝土厂或施工现场混凝土质量的提高和稳定是有用的，但在任何情况下，都必须考虑到试验中批次混凝土的取样。(4)本方法适用于具有特殊性能的高强混凝土。由于预期配合比的微小差异会影响其性能，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.