Distinct-layer casting of SCC: The mechanical consequences of thixotropy

Roussel, Nicolas; Cussigh, François

doi:10.1016/j.cemconres.2007.09.023

Cited by 208 publications

(110 citation statements)

References 19 publications

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“…It has been shown that the structural build-up properties of cement-based materials can be used to predict or optimize concrete production. For instance, formwork pressure reduction or distinct-layer casting issues can be predicted using the structural build-up rate of self-compacting concrete [21][22][23][24]. In the present case, structural build-up is used to describe and model the competition between the load increase, linked to the building rate, and the mechanical strength of the first deposited layer of the structure which is linked to the cement-based material yield stress.…”

Section: Introductionmentioning

confidence: 99%

Structural built-up of cement-based materials used for 3D-printing extrusion techniques

2015

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Additive manufacturing and digital fabrication bring new horizons to concrete and cementbased material construction. 3D printing inspired construction techniques that have recently been developed at laboratory scale for cement-based materials. This study aims to investigate the role of the structural build-up properties of cement-based materials in such a layer by layer construction technique. As construction progresses, the cement-based materials become harder with time. The mechanical strength of the cement-based materials must be sufficient to sustain the weight of the layers subsequently deposited. It follows that the comparison of the mechanical strength, which evolves with time (i.e. structural buildup), with the loading due to layers subsequently deposited, can be expected to provide the optimal rate of layer by layer construction. A theoretical framework has been developed to propose a method of optimization of the building rate, which is experimentally validated in a layer-wise built column.

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Section: Introductionmentioning

confidence: 99%

Structural built-up of cement-based materials used for 3D-printing extrusion techniques

2015

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“…Static stability, flowability, segregation resistance, formwork pressure and its decay after casting, air entrapment, surface quality and interlayer bond strength between consecutive concrete layers strongly depend on rheology and thixotropy of SCC [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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

Ahari

Erdem

Ramyar

2015

Construction and Building Materials

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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.

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“…Moreover, a concrete with a high degree of thixotropy may show high segregation resistance [5] and decrease lateral pressure exerted on the formwork system [14] while high thixotropy may lead to an increase in entrapment of air in fresh concrete and formation of lift lines in multilayer casting [15]. Such opposite effects may be remedied by the combined use of the SCM.…”

Section: Introductionmentioning

confidence: 99%

“…SCC behaves thixotropically showing good segregation resistance and low lateral pressure on formwork whereas it probably can increase entrapped air in fresh concrete and lift lines in multilayer casting, reducing bond strength between layers [15,31,35]. Therefore, for a given application the mixture parameters of SCC should be adjusted to achieve a given profile of thixotropic properties that can take into account the various requirements.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, the study of thixotropy and structural breakdown of SCC has become an interesting area of research owing to the fact that it would help concrete technologists to predict some aspects such as the static stability, segregation resistance, formwork pressure and its decay after casting, air entrapment, surface quality, interlayer bond strength between consecutive concrete layers and pumpability of concrete [15,[30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

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Thixotropy and structural breakdown properties of self consolidating concrete containing various supplementary cementitious materials

Ahari

Erdem

Ramyar

2015

Cement and Concrete Composites

103

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Supplementary cementitious materials Thixotropy Breakdown Drop in apparent viscosity Yield value at rest a b s t r a c tIn 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.

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Distinct-layer casting of SCC: The mechanical consequences of thixotropy

Cited by 208 publications

References 19 publications

Structural built-up of cement-based materials used for 3D-printing extrusion techniques

Structural built-up of cement-based materials used for 3D-printing extrusion techniques

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

Thixotropy and structural breakdown properties of self consolidating concrete containing various supplementary cementitious materials

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