Superplasticizers and the rheology of concrete

Flatt, Robert J.; Schober, I.

doi:10.1533/9780857095282.2.144

Cited by 116 publications

(109 citation statements)

References 44 publications

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“…This is confirmed by the results of studies of the disperse-coagulation structure of alkaline cement paste in terms of plastic strength [14]. Variability of cement formulation at which effectiveness of surface-active substances (SAS) is ensured was shown in [11]. At the same time, there is no systematization of SAS from the point of view of selective action with an account for cement composition and the nature of processes taking place at an early stage of cement stone structure formation was not disclosed.…”

Section: Analysis Of Plasticizer Effectiveness During Alkaline Cementmentioning

confidence: 63%

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Analysis of plasticizer effectiveness during alkaline cement structure formation

Kryvenko

Runova

Rudenko

et al. 2017

EEJET

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Проаналізовано проблему пластифікації цементів, лужне середовище яких визначає при-сутність сполук лужних металів, та запропоно-вано шляхи її вирішення. В якості альтернативи суперпластифікаторам на основі складних поліе-фірів запропоновано широке коло поверхнево-ак-тивних речовин, придатних для пластифікації лужних цементів. Органічні сполуки системати-зовані за ефективністю дії як пластифікатори лужних цементів Ключові слова: лужний цемент, хімічна добав-ка, поверхнево-активна речовина, гранульований доменний шлак, цементне тісто, пластична міц-ність Проанализирована проблема пластификации цементов, щелочную среду которых определя-ет присутствие соединений щелочных метал-лов, и предложены пути ее решения. В каче-стве альтернативы суперпластификаторам на основе сложных полиэфиров предложен широ-кий круг поверхностно-активных веществ, при-годных для пластификации щелочных цементов. Органические соединения систематизированы по эффективности действия в качестве пластифи-каторов щелочных цементов Ключевые слова: щелочной цемент, химиче-ская добавка, поверхностно-активное вещество, гранулированный доменный шлак, цементное тесто, пластическая прочность UDC 691.5

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Section: Analysis Of Plasticizer Effectiveness During Alkaline Cementmentioning

confidence: 63%

“…The paper [11] indicates necessity of modifying molecular structure of plasticizers taking into account changes in the mechanism of adsorption of such admixtures in an alkaline medium and in their manifestation of dispersing functions in dispersions of alkaline cements.…”

Section: Analysis Of Plasticizer Effectiveness During Alkaline Cementmentioning

confidence: 99%

Analysis of plasticizer effectiveness during alkaline cement structure formation

Kryvenko

Runova

Rudenko

et al. 2017

EEJET

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“…(ii) The pastes undergo a chemical reaction with time [2,[4][5], changing the rheological properties. (iii) A majority of the developed chemical admixtures are designed to either change the properties of the suspending medium, the interaction forces between the particles, or to change the rate at which the chemical reaction occurs [6]. As such, cement pastes are typically thixotropic materials with a yield stress and varying rheological properties over time.…”

Section: Introductionmentioning

confidence: 99%

Measuring Rheological Properties of Cement Pastes: Most common Techniques, Procedures and Challenges

et al. 2017

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The science of rheology is increasingly used to describe the properties of fresh cement paste. Compared to standard workability tests, rheological properties allow for more fundamental investigation, more precise phenomenological description of flow properties and serve as input for numerical simulations. Standard commercially available rheometers are typically used to perform those measurements. However, the results of the measurement depend on the geometry, testing procedure and a number of potential artefacts. This technical letter describes the most common techniques and procedures used to assess the rheological properties of cement paste, as well as challenges during measurements and actions to counter these challenges.

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“…The rheology of concrete can be affected by a vast variety of parameters. With increasing complexity of cementitious binders and considering the complex interaction between cement and rheology modifying admixtures on the micro scale [25][26][27][28][29][30][31][32][33][34] the variety of possible rheology changing influences is becoming significantly worse.…”

Section: Challenges For Decision Makingmentioning

confidence: 99%

Concrete casting robustness improvement due to active rheology

2018

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Abstract. With ongoing innovation in process technology, the challenges of concrete technology are more and more focused on the rheological optimisation for these processes, since improper mixture stability or poor compaction ability negatively affect the concrete homogeneity and quality. However, along with the increasing complexity of today's concrete mixture compositions, concrete becomes more prone to failure regarding the casting process. Variable properties of the raw materials typically cause changing workability. The reasons can be found among others in scattering water contents, physical or chemical properties of the cement or varying environmental temperatures. Robustness in the delicately adjusted rheology, however, is of utmost importance for modern and future process technology, from sprayed concrete over pumpable concrete towards 3D-printing, with regard to the long-term strength, the function and the durability. Typically, material induced changes cannot be identified easily due to the complex interactions of concrete constituents. Therefore, a precise and prompt counteraction is impossible. However, it is known that the yield stress can be controlled by addition of supplementary superplasticizer or stabilising agent. In combination with computerized process observation tools that can rapidly interpret and react on changes in the rheology, it is therefore thinkable, that only these two admixture types can adjust the rheology steadily and permanently, regardless of the actual root cause for observed macroscopic rheology change. The presentation will firstly give a comprehensive overview of effects at the interface between pore solution, particles and hydrates, which affect the rheology of fresh concrete. Secondly, ways are recommended how the rheology can be actively manipulated before eventually computerized methods are demonstrated that help to actively and rapidly assess and counteract performance scatter during steady casting processes.

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Superplasticizers and the rheology of concrete

Cited by 116 publications

References 44 publications

Analysis of plasticizer effectiveness during alkaline cement structure formation

Analysis of plasticizer effectiveness during alkaline cement structure formation

Measuring Rheological Properties of Cement Pastes: Most common Techniques, Procedures and Challenges

Concrete casting robustness improvement due to active rheology

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