Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

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Author: search.filters.author.Ramyar, KambizSubject: search.filters.subject.Thixotropy

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  • Article
    Citation - WoS: 27
    Citation - Scopus: 30
    Time-Dependent Rheological Characteristics of Self-Consolidating Concrete Containing Various Mineral Admixtures
    (Elsevier Ltd., 2015) Saleh Ahari, Reza; Erdem, Tahir Kemal; Ramyar, Kambiz
    The study herein was intended to evaluate the influence of elapsing time on rheological properties and thixotropy of self-consolidating concrete (SCC) mixtures containing various mineral admixtures. For this purpose, variation of T50 flow time, torque plastic viscosity, apparent yield stress and thixotropy were investigated as a function of time in a standstill condition. Various amounts of silica fume (SF), metakaolin (MK), Class F fly ash (FAF), Class C fly ash (FAC) and granulated blast-furnace slag (BFS) were utilized in binary, ternary and quaternary cementitious blends in 17 different SCC mixtures having a constant slump flow value. The results showed that SCC mixtures containing various mineral admixtures were highly stable or moderately stable (VSI between 0 and 1) at 0 min according to ASTM C 1611. However, mixtures containing FAC, FAF and BFS exhibited some bleeding and segregation at 50 min. In a standstill condition, apparent yield stress and thixotropy increased significantly with time while torque plastic viscosity values changed only in a limited range. In addition, with elapsing time, MK and FAC were found to have more influence on torque plastic viscosity and yield stress values in comparison with the other admixtures. However, increase in the yield values were more pronounced in comparison with the torque plastic viscosity values. Increase in thixotropy with time for the SF and MK blended mixtures were higher when compared to the control mixtures and mixtures containing the other mineral admixtures.
  • Article
    Citation - WoS: 111
    Citation - Scopus: 132
    Thixotropy and Structural Breakdown Properties of Self Consolidating Concrete Containing Various Supplementary Cementitious Materials
    (Elsevier Ltd., 2015) Ahari, Reza Saleh; Erdem, Tahir Kemal; Ramyar, Kambiz
    Abstract In this study, thixotropy and structural breakdown of 57 self-consolidating concrete (SCC) mixtures containing various supplementary cementitious materials (SCM) were investigated by different approaches. The effects of SCM type and content on high range water reducer demand and plastic viscosity were also studied. For these purposes, various amounts of silica fume (SF), metakaolin (MK), Class F fly ash (FAF), Class C fly ash (FAC) and granulated blast-furnace slag (BFS) were utilized in binary, ternary, and quaternary cementitious blends in three water/binder (w/b) ratios. Results showed that except BFS, use of SCM in SCC mixtures increased thixotropy values in comparison with the mixtures containing only portland cement (PC). Good correlations were established between structural breakdown area and drop in apparent viscosity values for all w/b ratios. The different methods used to evaluate the thixotropy and structural breakdown got more consistent with each other as w/b decreased.