Quantitative evaluation of segregation behaviors of fresh concrete and influential factors on them

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This research aims to clarify quantitatively the segregation behaviors of fresh concrete by a microscopic approach, and to develop a segregation resistibility test method. The results of present work can be summarized as follows.(1)One-side shear test apparatus incorporating laser irradiation device was made and used to examine, by means of Laser-Aided-Tomography, the movement of irregular particles under shear force. The observed information such as changes in contact angles and moving distance of the particles were used for later theoretical parts of this work.(2)Characteristics and behavior of granular materials in fresh concrete were theoretically investigated based on the multi-phase structural model, which had been proposed by Li, co-operator of present work, to clarify mechanical constitutive laws of fresh concrete under both non-vibrated and vibrated conditions, and a non-linear deformation resistibility model of fresh concrete was proposed.(3)Using the mechanical constitutive … More laws, segregation behaviors of coarse aggregate particles in fresh concrete were investigated to formulate their mean sedimentation rate for the cases where concrete was in a standstill or vibrated state or in the state of deforming and/or flowing. Also, effects of various factors on the segregation rate, including mean particle size, fluidity of fresh concrete, elapsed time, difference in density between coarse aggregate and matrix mortar, normal stress, and others were quantitatively clarified.(4)After formulating pore water pressure and its change with time for fresh concrete in both static and vibrated states, equations for expressing both amount and rate of bleeding were derived by applying Darcy Law to bleeding of fresh concrete, and factors influencing on the bleeding phenomena were quantitatively clarified.(5)A formula of deviation ratio of gravity center, which could be used to evaluate the degree of segregation of fresh concrete, was deduced, and a segregation resistibility model was suggested for fresh concrete in static state.(6)A series of shear tests were made to verify the mechanical constitutive law of fresh concrete using an apparatus which was a stratified shear box incorporated with an γ-ray density meter. This apparatus was proposed for testing the segregation resistibility of fresh concrete. Less