Time-dependent rheological characteristics of self-consolidating concrete containing various mineral admixtures

Abstract

h i g h l i g h t sTime-dependent rheology of SCC with various mineral admixtures was investigated. Apparent yield stress and thixotropy of SCC increased significantly with time. Time-dependent torque plastic viscosity values changed only in a limited range. Viscosity and yield stress were affected mostly by metakaolin and Class C fly ash. Metakaolin and silica fume, had more influence on thixotropy as time was elapsed. a r t i c l e i n f o t r a c tThe 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 T 50 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.

Assessment of the fresh selfcompacting concrete properties utilizing different types of additives

“…This could be explained by the ball bearing effect and additional lubrication provided by spherical and smooth-textured of SF particles. This finding is consistent with the following references [18][19][20].…”

Effects of mix-design variables on the workability, rheology and stability of self-consolidating concrete

“…It is known from the literature (Bartos, Sonebi, & Tamimi, 2002;EFNARC, 2005;Saleh Ahari, Erdem, & Ramyar, 2015) that viscosity can be estimated by V-funnel and T500 test. This information was verified in Figure 6b and 6c.…”

Method for calculating dynamic yield stress of fresh cement pastes using a coaxial cylinder system

“…(10) into Eq. (15) gives Equations ( 15) and ( 16) can both be used to solve the Couette inverse problem of a coaxial cylinder rheometer. Specifically, Eq.…”

“…Substituting the expressions of a Newtonian fluid model and the Bingham model into Eq. (15) gives two function expressions that are the same as the Margule 56 and Reiner-Riwlin equations. This verifies the accuracy of the derivation process.…”

“…The rheological characteristics of the paste gradually change with an increase in the shear rate (i.e., a single shear thickening or shear thinning is not observed in the shear test), making it challenging to determine a specific and suitable rheological model for characterizing the rheological parameters. [15][16][17] Cement paste can resist an external shear force and not flow. This resistance, defined as the yield stress, arises from the microcosmic network structure formed by colloidal interactions, [18][19][20] and it depends on the strength and structure of this network in the cement paste.…”