Applicability and Significance of Rheometric Tests for Rheology of Fluid and Self-Leveling High-Strength Concrete

1997 ◽  
Vol 1574 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Moncef Nehdi ◽  
Sidney Mindess
Keyword(s):  
Ultrafine Particles ◽  
Flow Behavior ◽  
High Strength ◽  
Partial Replacement ◽  
Test Fluid ◽  
Rheological Characterization ◽  
Bingham Model ◽  
Shear Rates ◽  
Concrete Mixtures ◽  
Two Parameters

The emergence of new special concretes on construction sites has shown that concretes of the same slump may behave quite differently on the job. For these concretes, one cannot rely on the traditional workability tests for quality control and rheological characterization. It has been claimed that the flow behavior of fresh concrete closely approximates the Bingham model and that at least two parameters are therefore needed to describe its rheology. Thus, rheological measurements must be carried out at not fewer than two shear rates. This study examines the applicability of the Bingham model to fluid and self-leveling highstrength concrete (HSC). Results obtained from a rheometer are compared with results of the standard slump test. Fluid concrete mixtures were investigated that had a water/binder ratio ( w/ b) of 0.33 and slump values of 200 ± 20 mm and incorporated proportions of limestone filler, silica fume, and ground silica as partial replacement (by volume) of cement. In addition, self-leveling concrete mixtures (torque viscosity ≤ 1 Nm at 15 min) having a w/ b ratio of 0.25 and 15 percent replacement of cement by various fillers were examined. The possibility of characterizing the rheology of fluid and self-leveling HSC on the basis of only two tests carried out at two different shear rates was addressed. An effort was made to define which is more relevant in a rheometer flow curve: the ascending part, the descending part, the maximum stress requirement, the flow resistance, the torque viscosity, or combinations of these factors. The possibility of measuring the rapid stiffening behavior of fresh HSC with time and the effect of ultrafine particles on the rheology using rheometric tests were also investigated.

scholarly journals Effect of Using River Sand on The Strength of Normal and High Strength Concrete

2018 ◽  
Vol 7 (4.20) ◽  
pp. 222 ◽  
Author(s):  
Haitham Al-Thairy
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
River Sand ◽  
Strength Concrete ◽  
Concrete Mixtures ◽  
Test Parameters ◽  
Normal Strength ◽  
Compressive And Flexural Strengths

The shortage and high cost of quarries sand in some regions around the world has motivated engineers and researchers to investigate the possibility and feasibility of using other materials to be used as a fine aggregate in concrete mixtures. The main objective of this research is to experimentally investigate the effect of using river sand as a partial replacement of the ordinary quarries sand on the mechanical properties of normal and high strength concrete. Nine concrete mixtures were prepared and tested in terms of fresh and hardened properties using different replacement ratios of the required proportion of the normal sand. Four replacement ratios were used for normal strength concrete (NSC) which are: 0%, 25%, 50% and 75%, whereas, five replacement ratios were used for high strength concrete (HSC) namely: 0%, 35%, 60% and 90%. For each strength grade, the test parameters of the prepared mixtures included compressive and tensile strength. The experimental test results have revealed that it is possible to obtain a normal and high strength concrete with acceptable compressive and flexural strengths values by using river sand with replacement ratios up to 25% and 35% for NSC and HSC, respectively. When the replacement ratios were increased to more than the aforementioned ratios, the strength of the concrete decreased accordingly.  

scholarly journals Rheological Characterization of a Concentrated Phosphate Slurry

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 178
Author(s):  
Souhail Maazioui ◽  
Abderrahim Maazouz ◽  
Fayssal Benkhaldoun ◽  
Driss Ouazar ◽  
Khalid Lamnawar
Keyword(s):  
Flow Behavior ◽  
Continuous Phase ◽  
Raw Material ◽  
Rheological Characterization ◽  
Phosphate Ore ◽  
Insoluble Particles ◽  
Experimental Protocols ◽  
Solid Liquid

Phosphate ore slurry is a suspension of insoluble particles of phosphate rock, the primary raw material for fertilizer and phosphoric acid, in a continuous phase of water. This suspension has a non-Newtonian flow behavior and exhibits yield stress as the shear rate tends toward zero. The suspended particles in the present study were assumed to be noncolloidal. Various grades and phosphate ore concentrations were chosen for this rheological investigation. We created some experimental protocols to determine the main characteristics of these complex fluids and established relevant rheological models with a view to simulate the numerical flow in a cylindrical pipeline. Rheograms of these slurries were obtained using a rotational rheometer and were accurately modeled with commonly used yield-pseudoplastic models. The results show that the concentration of solids in a solid–liquid mixture could be increased while maintaining a desired apparent viscosity. Finally, the design equations for the laminar pipe flow of yield pseudoplastics were investigated to highlight the role of rheological studies in this context.

scholarly journals Abrasion Resistance of Ultra-High-Performance Concrete for Railway Sleepers

2021 ◽  
Author(s):  
Ariful Hasnat ◽  
Nader Ghafoori
Keyword(s):  
Prestressed Concrete ◽  
Abrasion Resistance ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Positive Influence ◽  
Cementitious Material ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Ultra High Performance Concrete

AbstractThis study aimed to determine the abrasion resistance of ultra-high-performance concretes (UHPCs) for railway sleepers. Test samples were made with different cementitious material combinations and varying steel fiber contents and shapes, using conventional fine aggregate. A total of 25 UHPCs and two high-strength concretes (HSCs) were selected to evaluate their depth of wear and bulk properties. The results of the coefficient of variation (CV), relative gain in abrasion, and abrasion index of the studied UHPCs were also obtained and discussed. Furthermore, a comparison was made on the resistance to wear of the selected UHPCs with those of the HSCs typically used for prestressed concrete sleepers. The outcomes of this study revealed that UHPCs displayed excellent resistance against abrasion, well above that of HSCs. Amongst the utilized cementitious material combinations, UHPCs made with silica fume as a partial replacement of cement performed best against abrasion, whereas mixtures containing fly ash showed the highest depth of wear. The addition of steel fibers had a more positive influence on the abrasion resistance than it did on compressive strength of the studied UHPCs.

scholarly journals Use of Ecofriendly Glass Powder Concrete in Construction of Wind Farms

2021 ◽  
Vol 11 (7) ◽  
pp. 3050
Author(s):  
Eva M. García del Toro ◽  
Daniel Alcala-Gonzalez ◽  
María Isabel Más-López ◽  
Sara García-Salgado ◽  
Santiago Pindado
Keyword(s):  
Wind Farm ◽  
Glass Powder ◽  
Wind Farms ◽  
Main Element ◽  
Partial Replacement ◽  
Surface Protection ◽  
Air Content ◽  
Concrete Mixtures ◽  
Strength Tests ◽  
Rate Of Substitution

Silicon is the main element in the composition of glass and it has been seen that it can be used as a partial replacement for cement in the manufacture of concrete. Different dosages of glass powder and cement were applied to manufacture the concrete mixes. Initially, the characteristics of fresh concrete were studied, such as consistency, air content, apparent density and workability. Secondly, compressive strength tests were performed on the different concrete mixtures produced. The consistency tests allowed us to classify these concretes within the group of fluids. The air content of these concretes increased with the rate of substitution of cement by glass powder, resulting in lighter concretes. Density tests showed that this parameter decreased as the rate of substitution of cement increased. A coefficient k has been calculated for the substitution of glass powder by cement in the binder, using the Bolomey formula. Also, a mathematical model has been proposed to further analyze the experimental data. Major contributions of this work were to study the possible application of this concrete in different dispersions as a surface protection layer against the action of corrosion, in wind turbine foundations as well as the stabilization of the wind farm roads.

scholarly journals Viscosity Model for Nanoparticulate Suspensions Based on Surface Interactions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2752
Author(s):  
Benedikt Finke ◽  
Clara Sangrós Sangrós Giménez ◽  
Arno Kwade ◽  
Carsten Schilde
Keyword(s):  
Mechanistic Model ◽  
Model Development ◽  
Rheological Behaviour ◽  
Hybrid Modelling ◽  
Shear Rates ◽  
Drag Forces ◽  
Boehmite Nanoparticles ◽  
Data Points ◽  
Two Parameters ◽  
Physical Phenomena

In this paper, a widely mechanistic model was developed to depict the rheological behaviour of nanoparticulate suspensions with solids contents up to 20 wt.%, based on the increase in shear stress caused by surface interaction forces among particles. The rheological behaviour is connected to drag forces arising from an altered particle movement with respect to the surrounding fluid. In order to represent this relationship and to model the viscosity, a hybrid modelling approach was followed, in which mechanistic relationships were paired with heuristic expressions. A genetic algorithm was utilized during model development, by enabling the algorithm to choose among several hard-to-assess model options. By the combination of the newly developed model with existing models for the various physical phenomena affecting viscosity, it can be applied to model the viscosity over a broad range of solids contents, shear rates, temperatures and particle sizes. Due to its mechanistic nature, the model even allows an extrapolation beyond the limits of the data points used for calibration, allowing a prediction of the viscosity in this area. Only two parameters are required for this purpose. Experimental data of an epoxy resin filled with boehmite nanoparticles were used for calibration and comparison with modelled values.

Application of Thermally Treated Sewage Sludge in Blended Cements

2014 ◽  
Vol 905 ◽  
pp. 191-194 ◽  
Author(s):  
Zbyšek Pavlík ◽  
Milena Pavlíková ◽  
Jan Fořt ◽  
Martina Záleská ◽  
Igor Medveď ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Waste Water Treatment ◽  
Treatment Plant ◽  
Diffraction Method ◽  
High Strength ◽  
Water Treatment Plant ◽  
Waste Water Treatment Plant ◽  
Partial Replacement ◽  
Blended Cements ◽  
Thermally Treated

Chemical, physical, morphological, and mineralogical analysis of sewage sludge originating from a waste water treatment plant in Patras, Greece, is presented in the paper. The sewage sludge is firstly dried at 70°C, then oven-burned at 700°C for two hours and milled. The thermally treated material is analyzed using XRF and XRD, the particle size distribution is determined by a laser diffraction method. A potential use of sewage sludge in blended cements is investigated on the basis of the measurement of mechanical and basic physical properties of pastes containing the sludge in an amount of up to 60% of the mass of cement. Experimental results show that the thermal treatment of pre-dried sewage sludge and its grinding provides a material that can be successfully applied as a partial replacement of Portland cement. At a production of blended cements for high strength concrete, an up to 20% cement replacement level can be recommended.

Formability Analysis of Fukui Stretch-Drawing and Square Cup Drawing Using Strain and Stress Based Forming Limit Curves

2017 ◽  
Vol 751 ◽  
pp. 167-172 ◽  
Author(s):  
Sansot Panich ◽  
Nopparat Seemuang ◽  
Taratip Chaimongkon
Keyword(s):  
Flow Behavior ◽  
High Strength ◽  
Forming Limit ◽  
Forming Limit Curve ◽  
Yield Criteria ◽  
Hardening Law ◽  
Stress Curve ◽  
Strain Paths ◽  
Cup Drawing ◽  
Better Than

In this work, the experimental and numerical analyses of Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) for Advanced High Strength Steel (AHSS) sheet, grade JAC780Y, are performed. Initially, the FLC is experimentally determined by means of the Nakazima Stretch forming test. Subsequently, the FLSC of investigated steel was plastically calculated using the experimental FLC data. Different yield criteria including Hill48, and Yld89, are applied to describe plastic flow behavior of the AHS steel and Swift hardening law is taken into account. Hereby, influences of the constitutive yield models on the numerically determined FLSCs are evaluated regarding to those results from the experimental data. The obtained stress based forming limits are affected significantly by the yield criteria. Finally, the experimental and numerical formability analyses of Fukui stretch-drawing and square cup drawing tests are studied through FLC and FLSCs. It is observed that all stress based curves can be used very well to describe material formability of the examined steel compared to the strain based FLC. The strain based FLC depend on forming history and strain paths change. In the other hand, the stress based FLC do not depend on these issue. In this study, it can be concluded that the FLSCs could predict failure more realistically and better than the strain based FLC.

The Characterization and Flow Behavior of 316L Stainless Steel Feedstock for Micro Metal Injection Molding (μMIM)

2010 ◽  
Vol 44-47 ◽  
pp. 2872-2876
Author(s):  
Pei Li Haw ◽  
Norhamidi Muhamad ◽  
Hadi Murthadha
Keyword(s):  
Stainless Steel ◽  
Injection Molding ◽  
316L Stainless Steel ◽  
Flow Behavior ◽  
Palm Stearin ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Binder System ◽  
Molding Process ◽  
Rheological Characterization

The rheological behaviors of the Micro Metal Injection Molding feedstock are important for the stability of the feedstock during micro injection molding process and quality of the final micro-components. Homogeneous feedstocks are preferable for MIM process to ensure the dimensional consistency of molded components and prevent the defects of powder-binder separation or particle segregation. In this work, feedstocks with various formulations of 316L stainless steel and binder system were prepared by using Brabender Plastograph EC Plus mixer. The binder system comprises of palm stearin, polyethelene (PE) and stearic acid. In order to obtain the viscosity, activation energy, flow behavior and mold ability index, the rheological characterization of the feedstocks were investigated in numerous conditions by using Shimadzu 500-D capillary rheometer The study showed that all of the 316L stainless steel feedstocks are homogenous with pseudo-plastic behaviors.

Properties of High Strength Fibre Reinforced Concrete Using Ultra Fine Slag

2016 ◽  
Vol 857 ◽  
pp. 183-188
Author(s):  
C. Mohan Lal ◽  
Vontary Sai Srujan Reddy
Keyword(s):  
High Strength Concrete ◽  
Steel Fibre ◽  
High Strength ◽  
Target Strength ◽  
Partial Replacement ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Design Requirement ◽  
Split Tensile Strength ◽  
Strength Concrete

High strength concrete has become a design requirement in recent years due to increase in number of infrastructure projects. This paper presents the effect of incorporating Ultra Fine Slag (UFS) and steel fibre to obtain high strength concrete. To achieve target strength of about 80 MPa, it is proposed to the replacement of cement of 10%, 20% and 30% with UFS and incorporating 0.5% and 1.0% fibre in concrete. An experimental investigation is carried out to find the mechanical properties of the concrete. From the test results, it was observed that a compressive strength of 95 MPa was achieved at 30% replacement of cement with UFS and 1.0% fibre content. In addition, there was a significant improvement in split tensile strength and flexural strength of the concrete. This study demonstrates that a high strength concrete can be obtained from partial replacement of cement with UFS and addition of steel fibre.

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