Establishment of Mix Design Method and Work Method of Mortar for Structures

本研究为编制结构用砂浆的配合比设计方法和工作方法（该砂浆采用特殊级配的细骨料来增加骨料体积，使其干燥收缩控制在与混凝土相同的水平，用于结构），进行了以下研究。骨料的偏析机理：利用模拟砂浆对振动压实作用下骨料的偏析过程进行了可视化研究。细骨料级配设计方法：研究了骨料级配与固含量的关系。提出了二、三粒径骨料固含量的预测方法。空气含量的影响：研究了结构用砂浆的空气含量对其新鲜性能的影响。确定了在不考虑空气含量的情况下，通过计算分散体之间的距离来综合估计砂浆的屈服值。振动压实法：研究了振动压实砂浆的流变性能和抗离析性能。并证实了结构砂浆可以采用类似于混凝土的振动压实法进行浇筑。强度特性及干缩：结构用砂浆的抗压强度与混凝土基本相等。2)杨氏模量可由JASS 5方程预测。3)干燥收缩可控制在与混凝土相同的水平。高流态化的可行性：研究了结构砂浆高流态化的可行性。确定水灰比小于42.5%时，结构砂浆坍落度流动可流化至70cm。

In this study, the following was investigated in order to prepare the mix design method and the work method of the mortar for structures (the mortar, of which aggregate volume is increased by using fine aggregate with special grading to control drying shrinkage to the same level as that of concrete, for applying to structures).1. Segregation mechanism of aggregate: The process of segregation of aggregate subjected to vibrating compaction was visualized using the simulated mortar.2. Design method of grading of fine aggregate: The relationship between the grading of aggregate and the solid content was investigated. And the prediction method of the solid content of aggregate composed of two or three grain size was advanced.3. Effect of air content: The effect of air content of the mortar for structures on fresh properties was investigated. And it was determined that the yield value of the mortar is estimated comprehensively based on the distance between aggregates in dispersion calculated ignoring air content.4. Vibrating compaction method: The rheological properties and the segregation resistance of the mortar for structures subjected to vibrating compaction were investigated. And it was confirmed that the mortar for structures can be cast with the vibrating compaction method similar to that for concrete.5. Strength characteristics and drying shrinkage: The following results for the mortar for structures were obtained: 1) Compressive strength is nearly equal to that of concrete. 2) Young's modulus can be predicted by the JASS 5 equation. 3) Drying shrinkage can be controlled to the same level as that of concrete.6. Feasibility of high-fluidization: The feasibility of high-fluidization of the mortar for structures was investigated. And it was determined that if water cement ratio is less than 42.5%, the slump flow of the mortar for structures can be fluidized to 70cm.