scholarly journals Rheological Properties Of Self-Consolidating Concrete Incorporating Natural And Industrial Pozzolans

2021 ◽  
Author(s):  
Asaad Mousa
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cost Effective ◽  
Sustainable Construction ◽  
Self Consolidating Concrete ◽  
Supplementary Cementing Materials ◽  
Passing Ability

Self-consolidation concrete (SCC) is the latest version of high performance concrete with excellent workability and high resistance to segregation and bleeding. The main objective of this project is to study the rheological properties of SCC incorporating natural and industrial pozzolans (silica fume and metakaolin, repectively) as supplementary cementing materials (SCMs). Use of such pozzolanic materials in the development of environmentally friendly and cost effective SCC can lead to sustainable construction. In this project eleven SCC mixtures are developed by incorporating different percentages of silica fume (SF) and metakaolin (MK) as replacement of cement. However, the water cement ratio of all SCC mixtures are optimized so that all mixtures satisfied the requirements of SCC in terms of fresh properties such as workability, stability, passing ability, bleeding and segregation resistance. This study particularly concentrates on evaluation of the rheological properties such as viscosity and yield stress of developed silica fume and metakaolin based SCC mixtures. The influence of SF and MK dosages on viscosity and yield stress of SCC mixtures are evaluated. Correlations among fresh and rheological properties are developed and critically reviewed to make recommendations.

scholarly journals Rheological Properties Of Self-Consolidating Concrete Incorporating Natural And Industrial Pozzolans

2021 ◽  
Author(s):  
Asaad Mousa
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cost Effective ◽  
Sustainable Construction ◽  
Self Consolidating Concrete ◽  
Supplementary Cementing Materials ◽  
Passing Ability

Self-consolidation concrete (SCC) is the latest version of high performance concrete with excellent workability and high resistance to segregation and bleeding. The main objective of this project is to study the rheological properties of SCC incorporating natural and industrial pozzolans (silica fume and metakaolin, repectively) as supplementary cementing materials (SCMs). Use of such pozzolanic materials in the development of environmentally friendly and cost effective SCC can lead to sustainable construction. In this project eleven SCC mixtures are developed by incorporating different percentages of silica fume (SF) and metakaolin (MK) as replacement of cement. However, the water cement ratio of all SCC mixtures are optimized so that all mixtures satisfied the requirements of SCC in terms of fresh properties such as workability, stability, passing ability, bleeding and segregation resistance. This study particularly concentrates on evaluation of the rheological properties such as viscosity and yield stress of developed silica fume and metakaolin based SCC mixtures. The influence of SF and MK dosages on viscosity and yield stress of SCC mixtures are evaluated. Correlations among fresh and rheological properties are developed and critically reviewed to make recommendations.

Influence of Glass Powder on Rheological Properties of Ultra-High Performance Concrete Paste

2021 ◽  
Vol 1036 ◽  
pp. 419-431
Author(s):  
Xue Li Nan ◽  
Jian Rui Ji ◽  
Rong Yang Li ◽  
Yi Wang ◽  
Hao Chen ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
High Performance ◽  
Glass Powder ◽  
High Performance Concrete ◽  
Shear Thickening ◽  
Plastic Viscosity ◽  
Ecological Problem ◽  
Ultra High Performance Concrete

Replacing cement and silica fume with glass powder to prepare ultra-high performance concrete (UHPC) is beneficial to solve the ecological problem in the field of civil engineering, but the technologies of preparation, transportation, pumping, and hardening of UHPC mainly relate to its rheological property. Therefore, this paper studied the influence of glass powder on the rheological properties of UHPC paste by performing the flow and the rheological test. Experimental results showed that when the cement and silica fume partially replaced by glass powder, the UHPC paste appears shear thickening, yield stress, plastic viscosity, and area of hysteresis loop decrease. This means that mixing glass powder can somehow inhibit the problems of segregation and bleeding of UHPC during pumping. In this manner, the dosage of the superplasticizer in UHPC is appropriately reduced, the filling capacity of UHPC during pouring is improved, and the energy required for UHPC in the pumping process is weakened. Compared with replacing cement, replacing silica fume with glass powder significantly increases the shear thickening and fluidity of UHPC paste, and at the same, reduces its yield stress and plastic viscosity. This indicates that the construction performance of UHPC is greatly improved with the replacement of silica fume. The fluidity and yield stress of UHPC paste satisfy the quadratic polynomial function relationship, and the replacement of cement and silica fume with glass powder should be less than 33% and 50%, respectively. Under this condition, the rheological properties of the UHPC paste are greatly improved and result in little negative impact on the mechanical properties of UHPC.

scholarly journals Use of condensed silica fume for making high-strength, self-consolidating concrete

2000 ◽  
Vol 27 (4) ◽  
pp. 620-627 ◽  
Author(s):  
A KH Kwan
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Self Consolidating Concrete ◽  
Concrete Mix ◽  
Binder Ratio ◽  
Condensed Silica Fume ◽  
Water Binder Ratio

A high concrete strength can be achieved by lowering the water/binder ratio and a high workability by adding a higher dosage of superplasticizer. However, a high-performance concrete with both high strength and high workability cannot be produced by just these means because lowering the water/binder ratio leads to lower workability and there is a limit to the increase in workability that can be attained by adding superplasticizer. To produce a high-strength, high-workability concrete, the concrete strength needs to be increased without lowering the water/binder ratio. This can be done by adding condensed silica fume. In this study, a series of trial mixing aimed at developing high-strength, self-consolidating concrete (mean cube strength >80 MPa and needs no compaction for consolidation) was carried out. Several mixes suitable for making such high-performance concrete have been developed and it was found that the addition of condensed silica fume may, under favourable conditions, increase not only the strength but also the workability of the concrete mix. Based on the trial mix results, charts for the design of high-strength, high-workability concrete mixes made of the studied constituents are presented.Key words: condensed silica fume, high-strength concrete, self-consolidating concrete.

scholarly journals Rheological Properties of Cement Pastes with Multiwalled Carbon Nanotubes

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Gintautas Skripkiunas ◽  
Ekaterina Karpova ◽  
Irmantas Barauskas ◽  
Joana Bendoraitiene ◽  
Grigory Yakovlev
Keyword(s):  
Carbon Nanotubes ◽  
Rheological Properties ◽  
Yield Stress ◽  
Multiwalled Carbon Nanotubes ◽  
High Performance ◽  
High Performance Concrete ◽  
Plastic Viscosity ◽  
Multiwalled Carbon ◽  
Cement Pastes ◽  
Rheological Test

The evaluation of rheological properties of cement systems is getting more relevant with growing interest to self-consolidating concrete (SCC), high-performance concrete (HPC) and ultrahigh-performance concrete (UHPC). The rheology models are a perspective tool to predict and manage the properties of cement systems in the fresh and hardened state. The current research is focused on the rheological test of cement systems modified by multiwalled carbon nanotubes (MWCNT) dispersion with and without polycarboxylate ether (PCE). The content of dispersion with 1% concentration of MWCNT in cement pastes varied from 0.125 to 0.5% by weight of cement. The dosage of PCE was taken as 0.6% by weight of cement. The cement pastes were prepared based on Portland cement without mineral additives. The rheological test was carried out at 5, 30, 60, and 120 min after mixing of cement paste. The rheological test established that modification of cement pastes by MWCNT dispersion in dosage 0.25% leads to the decrease of yield stress by 30.7% and increase of plastic viscosity by 29.6%. The combined modification by PCE and MWCNT dispersion shows the decrease in plastic viscosity of cement pastes by 9.90% in dosage of MWCNT equal to 0.5% by weight of cement, reduction of water demand by 20% for the same workability, and decrease of yield stress till 0 Pa. It gives the ability to obtain the self-compacting mixtures. The cement pastes with and without MWCNT dispersion revealed the shear-thinning behavior during 120 min after mixing. The modification of cement pastes by PCE with and without MWCNT dispersion showed the shear-thickening behavior which remains during 120 min after mixing.

Effect of Copper Slag as a Fine Aggregate on the Durability Characteristics of High-Performance Concrete (HPC) Containing Silica Fume

2020 ◽  
Vol 07 (02) ◽  
pp. 1-10
Author(s):  
Rizwan Ahmad Khan ◽  
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Copper Slag ◽  
Chloride Penetration ◽  
Interfacial Transition Zone ◽  
Fine Aggregate ◽  
Fresh Properties ◽  
Fine Aggregates ◽  
Effect Of Copper

This paper investigates the fresh and durability properties of the high-performance concrete by replacing cement with 15% Silica fume and simultaneously replacing fine aggregates with 25%, 50%, 75% and 100% copper slag at w/b ratio of 0.23. Five mixes were analysed and compared with the standard concrete mix. Fresh properties show an increase in the slump with the increase in the quantity of copper slag to the mix. Sorptivity, chloride penetration, UPV and carbonation results were very encouraging at 50% copper slag replacement levels. Microstructure analysis of these mixes shows the emergence of C-S-H gel for nearly all mixes indicating densification of the interfacial transition zone of the concrete.

scholarly journals A simulation-based approach to evaluate objective material parameters from concrete rheometer measurements

2019 ◽  
Vol 29 (1) ◽  
pp. 130-140 ◽  
Author(s):  
Florian Gerland ◽  
Alexander Wetzel ◽  
Thomas Schomberg ◽  
Olaf Wünsch ◽  
Bernhard Middendorf
Keyword(s):  
Yield Stress ◽  
High Performance ◽  
Evaluation Method ◽  
High Performance Concrete ◽  
Direct Determination ◽  
Plastic Viscosity ◽  
Flow Properties ◽  
Fresh Sample ◽  
Material Parameters ◽  
Simulation Based

Abstract Modern concretes such as ultra-high performance concrete (UHPC) show excellent strength properties combined with favorable flow properties. However, the flow properties depend strongly on process parameters during production (temperature, humidity etc.), but also change sensitively even with slight variations in the mixture. In order to ensure desired processing of the fluidlike material and consistent process quality, the flow properties of the concrete must be evaluated quantitatively and objectively. The usual evaluation of measurements from concrete rheometers, for example of the ball probe system type, does not allow the direct determination of the objective material parameters yield stress and plastic viscosity of the sample. We developed a simulation-based method for the evaluation of rheometric measurements of fine grained high performance concretes like self-compacting concrete (SCC) and UHPC. The method is based on a dimensional analysis for ball measuring systems. Through numerical parameter studies we were able to describe the identified relationship between measuring quantities and material parameters quantitatively for two devices of this type. The evaluation method is based on the Bingham model. With this method it is possible to measure both the yield stress and the plastic viscosity of the fresh sample simultaneously. Device independence of the evaluation process is proven and an application to fiber-reinforced UHPC is presented.

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