Structural Build-up Research Articles

Viscoelastic properties of fresh cement paste: measuring procedures and influencing parameters

Fresh cement pastes behave as viscoelastic materials below the flow onset. The measurements of viscoelastic properties of fresh cement paste provide valuable insight into the dispersion of solid particles as well as the hydration kinetics at early age and its influence on the structural evolution and solidification behavior at quasi-static conditions. Monitoring the development of viscoelastic properties of fresh cement paste using dynamic oscillatory shear measurements can also elucidate the working mechanisms of chemical admixtures. These properties are efficient indicators to guide mixture proportion design and are necessary to understand the rheology and stability of concrete. In this paper, the most common techniques, including dynamic oscillatory measurements, used to assess the viscoelastic properties of fresh cement paste are presented and discussed. The measurement challenges and their effects on the accuracy of the obtained properties are highlighted. On the other hand, the effects of high-range water-reducer, viscosity-modifying admixture, and supplementary cementitious materials are discussed. Furthermore, the use of viscoelastic measurements to assess yield stress and structural build-up of cement paste is presented.

Thixotropy of superplasticized cement pastes – Underlying mechanisms considering the polycarboxylate molecular structure, interparticle interactions and hydration kinetics

This paper deals with the decisive mechanisms of thixotropic structural build-up in superplasticized cement-based suspensions related to the PCE molecular structure. We investigate the effect of the side chain length and anionic charge ratio of tailored PCE superplasticizers on thixotropic structural build-up under quantitative consideration of colloidal and contact interactions as well as very early hydration kinetics. The thixotropic structural build-up of superplasticized cement pastes with systematically varying the PCE molecular structure was investigated at constant workability, i.e. dynamic yield stress, by adjusting the individual PCE dosage. Thixotropy was quantified using plate-plate rheometry, while at the same time superplasticizer adsorption, specific surface area, granulometric measurements and quantitative XRD analysis provided an experimental basis for the identification of the respective contribution to the structural build-up.Our results show that the thixotropic structural build-up increases with decreasing PCE side chain length and increasing anionic charge ratio. This is due to accelerated very early hydration kinetics, causing an increase in the specific surface area. The latter is primarily attributed to ettringite, modifying the particle size distribution of the hydrated cement paste. Our approach of separating the colloidal and contact interactions indicates that the PCE-induced change in particle size distribution due to accelerated ettringite formation as well as the change in the average effective layer thickness are the dominant mechanisms for the thixotropic structural build-up in this context.

Damage-rheology model for predicting 3D printed concrete buildability

Insufficient buildability during printing can result in structural instability of three-dimensional (3D) printed concrete. A damage-rheology model was developed to predict such structural failure by simulating the early-age behavior of 3D printed concrete. The model captures essential characteristics of early-age concrete, including structural build-up, softening damage, irreversible deformation, and creep effect. Based on continuum damage mechanics, the model integrates the damage-plasticity theory and the Burgers model. A time-dependent thixotropic model is used to characterize the structural build-up behavior, considering the evolution of material properties as functions of the structural parameter. The model is systematically validated by comparing its predictions with uniaxial creep, straight-wall printing, and hollow-cylinder printing tests. The study investigates the effect of early-age creep on structural responses. Numerical results demonstrate the ability of the model to accurately predict the buildability of early-age 3D printed concrete.

Data provenance - from experimental data to trustworthy simulation models and standards

FAIR (findable, accessible, interoperable and reusable) data usage is one of the main principals that many of the research and funding organizations include in their strategic plans, which means that following the main principals of FAIR data is required in many research projects. The definition of data being FAIR is very general. When implementing that for a specific application or project or even setting a standardized procedure within a working group, a company or a research community, many challenges arise. In this contribution, an overview about our experience with different methods and tools is outlined.We begin with a motivation on potential use cases for the application of FAIR data with increasing complexity starting from a reproducible research paper over collaborative projects with multiple participants such as Round-Robin tests up to data-based models within standardization codes, applications in machine learning or parameter estimation of physics-based simulation models.In a second part, different options for structuring the data (including metadata schema) are discussed. The first one is the openBIS system, which is an open-source lab notebook and PostgreSQL based data management system. A second option is a semantic representation using RDF based on ontologies for the domain of interest.In a third section, requirements for workflow tools to automate data processing are discussed and their integration into reproducible data analysis is presented with an outlook on required information to be stored as metadata in the database.Finally, the presented procedures are exemplarily demonstrated for the calibration of a temperature dependent constitutive model for additively manufactured mortar. A metadata schema for a rheological measurement setup is derived and implemented in an openBIS database. After a short review of a potential numerical model predicting the structural build-up behavior, the automatic workflow to use the stored data for model parameter estimation is demonstrated.

Cathepsin B knockout confers significant brain protection in the mouse model of stroke

BackgroundSignificant advances have been made in our understanding of the endolysosomal cycle. Disruption of this cycle leads to cell death. The objective of this study aims to investigate the role of disrupted endolysosomal cycle in brain ischemia-reperfusion injury. MethodsA total of 57 mice were randomly assigned into four experimental groups: (i) wildtype (wt) sham control; (ii) wt middle cerebral artery occlusion (MCAO); (iii) cathepsin B (CTSB) knockout (KO) sham control; and (iv) CTSB KO MCAO. Mice were subjected either to 0 min (sham) or 40 min of MCAO, followed by reperfusion for 1 or 7 days. Physical and behavioral examinations were conducted in the 7-day reperfusion group for 7 consecutive days after MCAO. Confocal microscopy was used to assess the levels, redistributions, and co-localizations of key endolysosomal cycle-related proteins. Histopathology was examined by light microscopy. ResultsConfocal microscopy revealed a significant accumulation of CTSB in post-ischemic penumbral neurons relative to those in the sham group. In addition, N-ethylmaleimide sensitive factor ATPase (NSF) was irreversibly depleted in these neurons. Furthermore, CTSB-immunostained structures were enlarged and diffusely distributed in both the cytoplasm and extracellular space, indicating the release of CTSB from post-ischemic neurons. Compared to wt mice, CTSB KO mice showed a significant decrease in hippocampal injury area, a significant increase in the number of survival neurons in the striatal core area, and a significant improvement in physical and functional performance in post-MCAO mice. ConclusionBrain ischemia leads to a cascade of events leading to inactivation of NSF, disruption of the endolysosomal cycle, endolysosomal structural buildup and damage, and the release of CTSB, eventually resulting in brain ischemia reperfusion injury. CTSB KO in mice protected the brain from ischemia-reperfusion injury.

Extrusion and structural build-up of 3D printing cement pastes with fly ash, nanoclays and VMAs

3D printing technology (3DP) has provided new design and structural opportunities for cement-based systems (CBS) in architectural construction. However, there are still some issues related to extrudability and buildability of CBS, which can be overcome by using components for CBS rheology control. In this study, three types of nanoclays, a bentonite (BEN), a sepiolite (SEP) and an attapulgite (ATT), and two viscosity modifying admixtures (VMAs), a poly-acrylamide (VMA1) and a methylcellulose ether (VMA2), were added to a reference cement-fly ash 3D printing paste to evaluate their impact on CBS rheological properties and their implications in extrusion and buildability for 3DP. A polycarboxylate-ether based high range water-reducing admixture (HRWRA) was used to reach a target stiff consistency. Four laboratory tests were used to assess paste rheology, extrusion and structural build-up. Proper and deficient material extrusion limits were defined considering cohesion and initial yield stress. It was found that the combination of VMA2 and SEP increased cohesion, enhancing extrusion and avoiding water drainage and frictional behavior of pastes, producing properly extrudable paste. SEP by itself also improved structural build-up. Besides, samples with NC and VMAs required larger amounts of HRWRA, delaying cement setting and compressive strength gain.

Rheological Behavior of Cement Paste: A Phenomenological State of the Art

With the interest aroused by the development of modern concretes such as printable or self-compacting concretes, a better understanding of the rheological behavior, directly linked to fresh state properties, seems essential. This paper aims to provide a phenomenological description of the rheological behavior of cement paste. The first part is devoted to the most common testing procedures that can be performed to characterize the rheological properties of cement suspensions. The second one deals with the complexities of the rheological behavior of cement paste including the non-linearity of flow behavior, the viscoelasticity and yielding, and the structural build-up over time.

Rheology characterization of 3D printing mortars with nanoclays and basalt fibers

3D printing has become one of the most innovative technologies for cement-based systems (CBS). However, recent studies have shown some issues related to printability and buildability (water drainage, plugs on extruder die, spreading of first layer, etc). To achieve a proper rheology control of CBS, it is essential to adapt the material fresh state properties (initial shear yield stress and structural build-up). In this study, a reference cement-based mortar with fly ash (25%), a 1:1.5 binder to sand ratio and a 0.38 water to binder ratio was used. A polycarboxilate ether-based superplasticizer was added until a consistency of around 1 kPa, measured with the cone-penetration test, was reached. Then, small amounts of several types of nanoclays (NC) in powder and slurry form (sepiolite, attapulgite and bentonite) and natural fibers were added to modify mortar rheological properties. The aim of the study was to characterize the rheological properties of 3D printing mortar samples with NC and basalt fibers (BF) to understand printability and buildability of this material. Cone-penetration test, flow table test and slump test were used to characterize 3D printing capacities. The cone-penetration test was performed in stirred and left at rest samples to assess shear yield stress before and after material deposition. Nanoclays showed a remarkable capacity to retain water and avoid drainage during extrusion but also to increase fresh state strength of material over time. Besides, they increased shear yield stress over time when left at rest. On the contrary, samples stirred over time did not show any increase of shear yield stress, especially samples with slurry nanoclays. Natural fibers also reduced drainage and enhance printability control regarding to reference mortar. BF also enhanced a performance on stirred sample but showed slightly changes on structural build-up at rest, mainly governed by NC effect.

Investigation of the viscoelastic evolution of reactive magnesia cement pastes with accelerated hydration mechanisms

Viscoelasticity of reactive magnesia cement (RMC) pastes containing 3 different hydration agents (HCl, Mg(CH3COO)2 and MgCl2) were investigated. Amplitude sweep, frequency sweep and time sweep of RMC pastes were examined within 3 h of hydration. Time-dependent evolution of storage modulus, loss modulus, phase angle, and shear stress were recorded. Measurements of pH, isothermal calorimetry, XRD, TG-DTG and FTIR were used to analyze hydration reaction and products. Addition of hydration agents (HAs) accelerated the growth rate of storage modulus/loss modulus over time. MgCl2 demonstrated the greatest acceleration influence, also reflected in non-destructive structural build-up and buildability related to 3D printing applications. Addition of MgCl2 and HCl advanced the initial setting time of RMC pastes to 100–110 min, during which yield stress reached maximum, and decreased afterwards. Within 3 h of hydration, pastes containing MgCl2 revealed lowest pH, highest heat release and brucite concentration. HAs inclusion precipitated brucite away from MgO particles in the bulk solution, creating a bridge between MgO particles and enabling denser microscopic network structure.

Rheology of cement pastes with calcium carbonate polymorphs

Naturally occurring limestone currently used for concrete production mainly consists of calcite, and the other two metastable forms of anhydrous calcium carbonate include aragonite and vaterite. In this research, all three calcium carbonate polymorphs were synthesized in laboratory conditions and their effects on cement rheology were investigated. After comprehensive characterization of the polymorphs, they were used as cement substitutes (20 wt%) to prepare pastes for rheological testing. Aragonite was found to increase the initial static yield stress, dynamic yield stress, and storage modulus of cement pastes, while calcite and vaterite did not. The rate of structural build-up was also enhanced by aragonite, as indicated by higher rates of static yield stress development and storage modulus increase over time. The underlying mechanisms of the rheological changes induced by the calcium carbonate polymorphs – geometric features, hydration kinetics, and surface charge – were discussed and supported with experimental evidence.

Improving structural build-up of limestone-calcined clay-cement pastes by using inorganic additives

In 3D concrete printing, fast structuration is a prerequisite for ideal buildability. This paper aims to study the impact of inorganic additives, i.e., CaCl2 and gypsum, on structural build-up and very early-age hydration of limestone-calcined clay-cement (LC3) pastes within the first 70–80 min. Results show that, increasing the dosage of CaCl2 or gypsum can accelerate storage modulus G' and static yield stress evolution with time, as well as increase chemically bound water (H) content and total specific surface area (SSAtotal). Furthermore, good correlations were found between G' and H content, as well as static yield stress and the ratio of free water content to SSAtotal. The acceleration by CaCl2 can be attributed to stimulating C3S and C3A hydration and promoting crystal formation, i.e., ettringite, portlandite, and Friedel’s salt. Additionally, the increase in gypsum percentage led to a large amount of unreacted gypsum in the system, resulting in an increase in SSAtotal.

Set-on-demand of alkali-activated slag mixture using twin-pipe pumping

To achieve the set-on-demand purpose of concrete for digital fabrication where the opposing requirements for pumpability and buildability exist during the process, an inline mixing strategy, named twin-pipe pumping, has been developed utilizing a static mixer to blend two separate streams to accelerate setting right before extrusion. The system was initially developed utilizing two streams including a Portland cement-based mixture (without accelerator) and a limestone powder-based mixture (with an accelerator but without cement). However, the high content of cement may result in higher material costs along with lower sustainability, given the fact that the production of Portland cement contributes to around 8% of global CO2 emissions. This study aims to develop an alkali-activated slag mixture to increase the sustainability in digital fabrication, using twin-pipe pumping. The constituent mixtures consisting of a slag-based (without alkali) and a limestone powder-based (with varying alkali content) mix were formulated and their rheological behavior was measured for good pumpability. Phase transition from liquid to solid phase, mechanical strength, and pore structure was evaluated. Twin-pipe pumping was used in a printing trial. Results showed that the alkali-activated slag mixture achieved fast phase transition for set-on-demand purposes by combining the alkali in the limestone-based mixture with the slag in the slag-based mixture. Increasing the NaOH concentration or incorporating nano clay improved the structural build-up for high buildability.

Effects of superabsorbent polymers (SAP) on the rheological behavior of cement mortars: A rheological study on performance requirements for 3D printable cementitious materials

While the potential of incorporating superabsorbent polymers (SAP) as an additive in 3D printing cementitious materials has been a subject of interest recently, little research has been conducted on the effects of SAP incorporation on the rheological properties of cement mortars and the required performance of 3D printable cementitious materials when no other additives, such as superplasticizer (SP), are present or when SAP is added up to 1.0% by weight of the binder. Accordingly, the effects of SAP on the rheological behavior of cement mortar were analyzed in this study from the perspective of the performance requirements for 3D printable material with the SAP dosage (0%, 0.5%, and 1.0% by weight of cement), SAP particle size (100–180 and 355–425 μm), and superplasticizer (SP) presence (polycarboxylate-ether) as variables. The rheological properties of cement mortars with the same initial slump flow (180 mm ± 5 mm) were measured using a vane rotational rheometer, and their conformance to the performance requirements for 3D printable cementitious materials was studied. Static yield stress, dynamic yield stress, and plastic viscosity were calculated for each specimen using measured torque data obtained from the stress growth and flow curve experiments. The ratios of static to dynamic yield stress, plastic viscosity, and thixotropic areas were analyzed from the perspective of pumpability and extrudability, whereas the yield stress evolution and structural build-up rate were analyzed from the perspective of buildability. The results demonstrated that although the rheological properties of the SAP-incorporated cement mortar with a low water–cement ratio were similar to those of the SAP-incorporated cement mortar with a high water–cement ratio when SP was incorporated, the change in rheological properties with time and shear differed. SAP incorporation promoted the structuration of the mixtures without SP that have a high water–cement ratio due to the physical effects of SAP particles, but the effect was reversed in the mixtures with SP and a low water–cement ratio due to the water migration kinetics associated with SAP. Because a low water–cement ratio with SP is commonly applied for 3D printable materials, the findings of this study indicate that the water migration kinetics of SAP critically determines the printability of cementitious materials mixed with SAP. Given that observed effects are substantial, SAP arguably has potential as a rheology modifier for 3D printable cementitious materials.

Effect of competitive adsorption between specialty admixtures and superplasticizer on structural build-up and hardened property of mortar phase of ultra-high-performance concrete

This study aims to enhance structural build-up of ultra-high-performance concrete (UHPC) without influencing the initial flowability, which is critical in repair applications (e.g., use of UHPC in thin bonded overlays for bridge deck rehabilitation). Specialty admixtures, such as a viscosity-modifying admixture (VMA), have been used to enhance the structural build-up at rest. However, the use of specialty admixtures can increase superplasticizer (SP) demand to maintain proper flowability; the synergistic effect of these admixtures on structural build-up is not well understood as the coupled admixture content can reverse the net effect on yield stress, viscosity, and thixotropy. In this study, VMAs including welan gum (WG), diutan gum (DG), and cellulose ether (CE) were used. Styrene-butadiene rubber (SBR) and acrylic ester (AE) latex polymers (LPs) that can enhance structural build-up and bond strength were also incorporated. The competitive adsorption between these specialty admixtures and SP and its effect on structural build-up, early-age hydration, compressive and pull-off strengths, porosity and entrapped air content of UHPC mortar (i.e., without fiber) were systematically investigated. Test results indicated that the incorporation of anionic WG and DG that exhibited high competitive adsorption with SP led to a 275%–450% enhancement in structural build-up despite the 55%–135% increase of SP demand. Such increase was limited to 130% when using CE, SBR, or AE that cannot effectively adsorb onto cement particles in the presence of SP. This was because the high competitive adsorption between specialty admixtures and SP strengthened the particle flocculation and promoted the cement hydration in the first hour; the latter resulted in 20%–40% enhancement in non-reversible component of structural build-up. Furthermore, the use of LP at low and moderate dosages secured high bond strength to normal strength mortar despite 8%–33% decrease in compressive strength given the increased capillary porosity. The use of VMAs increased the entrapped air and resulting 5%–15% lower compressive strength, while the bond strength was not influenced.

Structural build-up and breakdown of alkali-activated slag pastes with different order of lignosulfonate and activator addition

One of the crucial issues of alkali-activated materials is the application of conventional plasticizers. Lignosulfonate plasticizer (LS) works well for sodium hydroxide-activated slag but loses its efficiency in sodium waterglass-activated slag because of competitive adsorption with silicates. Therefore, the effects of the timing of LS and activator addition on the structural build-up and breakdown of AAS pastes with low-silicate moduli activator (0 to 0.50) were investigated, particularly by means of non-traditional strain sweep tests, which are thoroughly discussed. The rheological tests were correlated with the Vicat needle test and isothermal calorimetry. The results showed the high efficiency of LS in NaOH-activated slag paste over time, regardless of the order of addition of the components of the paste. It was accompanied by a considerable retardation effect of LS on the hydration of AAS. The beneficial effect of LS on the rheological parameters and hydration kinetics decreased rapidly with an increase of the silicate modulus of the activator. The delayed addition of the concentrated silicate-containing activators completely counteracted the slightly beneficial effect of LS and even accelerated the initial structural build-up.

Accelerating the reaction process of sodium carbonate-activated slag mixtures with the incorporation of a small addition of sodium hydroxide/sodium silicate

This paper investigates the possibility of accelerating the slowly progressive early reaction process of sodium carbonate-activated slag mixtures by adding a small amount of sodium hydroxide or sodium silicate to the sodium carbonate activator. The reaction process of sodium carbonate-activated slag mixtures was evaluated by isothermal calorimetry and ultrasonic wave technology. Test results showed that adding a small amount of sodium hydroxide or sodium silicate to the sodium carbonate activator significantly accelerated the reaction process, resulting in shortened setting times and enhanced mechanical properties. Only 1% Na2O contribution from sodium hydroxide addition can lead to a 2-d compressive strength of 20 MPa for sodium carbonate-activated slag mixtures. In addition, the 28 days compressive strength was significantly higher than the sole sodium carbonate activator. The addition of sodium hydroxide or sodium silicate also considerably influenced the rheological behavior of the sodium carbonate-activated slag mixture, enhancing the structural build-up rate and transforming the shear-thinning behavior to Bingham or shear-thickening behavior. A more well-packed microstructure was observed in the mixtures with the addition of sodium hydroxide; however, more micro-cracks were observed in the mixtures with a small incorporation of sodium silicate.

RILEM TC 266-MRP: round-robin rheological tests on high performance mortar and concrete with adapted rheology—rheometers, mixtures and procedures

Recent developments in understanding the rheology of mortar and concrete as well as applying this understanding in the practice of construction necessitate an accurate assessment of materials’ rheological properties. It is well known that different rheometers for mortar and concrete deliver different results, as this was shown over 15 years ago in two measuring campaigns comparing concrete rheometers. Considering newly developed rheometers, including those to evaluate interface rheology and structural build-up at rest, as well as additional measurement procedures and data interpretation techniques, a new comparison campaign was carried out in 2018 at the Université d’Artois, in Bethune, France. This new campaign focused on measuring workability characteristics, flow curves, static yield stress values, interface properties and tribological data. A total of 14 different devices capable of measuring one or more of the above-mentioned characteristics were employed. These devices included four ICAR rheometers, the Viskomat XL, the eBT-V, the RheoCAD (two geometries), the 4SCC rheometer (two geometries), the plate test, the sliding pipe rheometer, a tribometer and an interface tool for the ICAR rheometer. This paper describes the mixture design and rationale of the five investigated concrete and three investigated mortar mixtures, design and analysis of the experiments, and comparison of test results. The findings confirmed some of the conclusions from two previous testing campaigns and expanded the findings to more modern concrete mixtures and more diversified sets of rheological devices. The investigated rheometers yielded different absolute values for material parameters, but they all were able to similarly distinguish between mixtures qualitatively. For static yield stress and interface rheology measurements, similar conclusions were obtained as for flow curves.

Nanomaterials as Promising Additives for High-Performance 3D-Printed Concrete: A Critical Review.

Three-dimensional (3D) printed concrete (3DPC), as one of the subset of digital fabrication, has provided a revolution in the construction industry. Accordingly, scientists, experts, and researchers in both academic and industry communities are trying to improve the performance of 3DPC. The mix design of all kinds of concrete has always been the most crucial property to reach the best efficiency. Recently, many studies have been performed to incorporate nano- and micro-scale additives to ameliorate the properties of 3DPC. The current study aims to present the main design properties of 3DPC and completely cover both fresh and hardened state characteristics of 3DPC containing different nano- and micro-additives. Our observations illustrate that nanomaterials can be mainly utilized as a thickener to ameliorate the thixotropic behavior and the structural build-up of 3DPC, resulting in higher yield stress and better viscosity recovery. Furthermore, each nanomaterial, through its unique impact, can provide lower porosity and permeability as well as better mechanical strengths for 3DPC. Although much research investigate the fresh properties of 3DPC containing nano and micro additives, future studies are needed to provide better insight into the impact of these kinds of additives on the hardened characteristics of 3DPC. In addition, researchers may devote more research to address the effects of the additives discussed herein on the performance of other kinds of 3DPC such as lightweight, self-compacting, etc. It should be noted that the effect mechanism of nanomaterials on the inter-layer bond strength of 3DPC is another crucial issue that should be investigated in future studies. Furthermore, nano-scale fillers from source of waste and biomass can be attractive additives for future research to achieve high performance of sustainable 3D-printed concrete.

Thixotropic characterisation of slag modified 3D printable metakaolin based geopolymer composite

Geopolymer concrete (GPC) is a substitute for ordinary Portland cement (OPC) in 3D concrete printing for sustainable construction. However, poor structural build-up arising from a slow chemical reaction rate of a two-part GPC is a limitation to buildability. Therefore, slag (0, 5, 10, and 15% by weight of metakaolin), and fibre (0.5% by volume of mix) inclusion in metakaolin (MK)-based GPC composite could improve structural build-up and enhance buildability. This paper presents the rheological thixotropic characterisation of static and dynamic yield stresses, Rthix (re-flocculation rate), and Athix (structuration rate), of slag-modified fibre-reinforced MK-based geopolymer for 3D printing of concrete using an ICAR rheometer at selected resting times of 0 to 2700 s depending on mix behaviour. The printability of the GPC is validated with a 3D concrete print of a 250 mm diameter column for each mix. The results show that the reference, M1, with 0% slag content is more workable than M2 with 5% slag; however, M2 exhibits better thixotropic properties. Slag inclusion in M2 improved the buildability of validated 3D prints by 36% compared to M1. The 3D prints of M1 and M2 columns are buildable up to 27 and 42 layers, respectively, before plastic yield and collapse. Slag inclusion beyond 5% had too little open time than required for printing, leading to a significant and early increase in stiffness and clogging of the printer hose.

Determination of optimum VMA utilization dosage in cementitious systems: In terms of rheological and flowability properties

In mixtures such as self-compacting concrete (SCC) and 3D printing concrete (3DPC) having a high amount of binder, utilization dosage of water-reducing admixture (WRA) is increased to provide the rheological requirements. In such a case, in addition to the increase in cost, the presence of a high dosage of WRA in the system can cause segregation in the SCC mixture and a decrease in the buildability capacity of the 3DPC mixture. However, the addition of viscosity-modifying admixture (VMA) to the mixture together with the WRA reduces the risk of bleeding and segregation in SCC mixtures and increases shape stability and buildability in 3DPCs. Nevertheless, it was emphasized that these properties were seriously affected by the VMA dosage. It was aimed to determine the optimum VMA utilization dosage by examining the effect of dosages of VMA on the rheological properties and flow performance of paste mixtures in this study. Paste mixtures containing 4 different dosages of VMA (0%, 0.2%, 0.4% and 0.6%) were prepared. In all mixtures, the w/c and the WRA dosage were 0.35 and 0.2%, respectively. The rheological properties of the mixtures were evaluated by measuring the dynamic yield stress (DYS), final viscosity value and structural build-up (Athix) parameters. In addition, flowability of mixtures was also examined. DYS value of all mixtures decreased with the increase in VMA utilization dosage. The highest viscosity and Athix values were measured in the mixture containing 0.4% VMA. However, the lowest DYS, viscosity and Athix values were determined in the 0.6% VMA-containing mixture. Flowability of the mixtures generally increased with the increase of VMA utilization dosage. The optimum VMA usage dosage was chosen to be 0.4% in terms of rheological properties.