Research of Efficient Methods of Superplasticizer Introduction into Cement Materials
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The article presents the results of researching efficiency of different modes of superplasticizer introduction in solution mixture with different consistency - from hard to plastic. The following methods of superplasticizer introduction into cement were researched: co-grinding of superplasticizer with cement, mixing cement with superplasticizer in dry state, introduction of superplasticizer into cement with mixing water, evaluation of water reduction effect of an additive depending on the methods of its introduction into cement and the time of determining its consistency. It is established that the most efficient method of superplasticizer introduction into plastic mixture is its co-grinding with cement.Keywords:
Superplasticizer
This paper shows how polycarboxylate based superplasticizer affects the initial setting time of cement paste. Three superplasticizers are used in this study with different properties and aiming to determine the delay in initial setting time due to superplasticizer. Initial setting time is calculated as per IS: 4031-PART 5-1988 with different SP dosages (0.5%, 0.75%, 1.0% and 1.5% of weight of cement). Superplasticizer is an admixture which reduces the water-cement ratio or increase the workability at the same water content. This paper deals with the evaluation of initial setting time due to superplasticizers.
Superplasticizer
Water–cement ratio
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By using XRD、SEM and other experimental methods, some details of polycarboxylate superplasticizer on the hydration products and performance of phosphogypsum-based cement(PBC) can be obtained. It can be found that the polycarboxylate superplasticizer makes the structure of the cement stone more compact, and significantly increases the strength of the cement. Besides, it can also improve the anti-carbonation and degradation properties of that cement.
Phosphogypsum
Superplasticizer
Degradation
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The incompatibility between the superplasticizer (SP) and cement can cause problems with the cementitious materials' fresh and hardened qualities, such as unstable workability, uncontrollable setting times, excessive air entrainment, and so on. In this paper, five various types of SPs were prepared. Their interaction with pure tricalcium aluminate (C3A) and its hydration products were investigated and their effect on the generation of Ettringite (AFt) and single-sulfur calcium sulphoaluminate hydrate (AFm) in paste and their compatibility with cement were also studied. The results demonstrate that after 15 min of cement hydration, the AFt and AFm content of mixture with polycarboxylate SP and sulfonated acetone-formaldehyde superplasticizer (PCA-SAF) is 124.6% and 24.8% higher than that of SAF, respectively, which decreases the consumption of SPs molecules and improves the compatibility of SAF with cement. Compared with polynaphthalene sulfonate superplasticizer (PNS), PCA-PNS dramatically enhanced the SP's compatibility with cement. Accelerating the production of AFt and AFm during the early stages of cement hydration may be one method to increase SP–cement compatibility.
Superplasticizer
Ettringite
Cementitious
Aluminate
Portlandite
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Because of less thorough study on the properties of cement pastes with superplasticizers and latex mixed together,the influence of different mixing procedures of superplasticizers and latex on the ζ potential of cement pastes(fresh) were analyzed using the ZetaProbe instrument.The experimental results show that with adding different use level(by mass) of polycarboxylic superplasticizer(PC),the cement pastes with both PC and latex added have negative or positive ζ potential.However,the ζ potential of cement pastes with both naphthalene formaldehyde condensate superplasticizer(NF) and latex added is lower than that of cement pastes with NF added but higher than that of cement pastes with latex added.Adding NF into cement pastes with latex added,the absolute value of equilibrium ζ potential of the cement pastes is lower than that of cement pastes with NF added,cement pastes with latex added and cement pastes with both NF and latex added.Adding PC into cement pastes with latex added,the ζ potential of the cement pastes can even reach the equilibrium ζ potential of cement paste with latex added.When latex is added in,the ζ potential of cement paste with 1.0% PC added doesn't change,but the ζ potential of cement paste with 0.1% PC added decreases greatly to a certain value.The ζ potential of cement paste with NF added increases from-10 mV to-6 mV when latex is added in,and then increases slowly with the increase of use level of latex.By adding superplasticizer(NF or PC) and latex into cement pastes simultaneously or adding latex into cement pastes with superplasticizer(NF or PC) added,the adsorbed proportion of polymer particles on cement grains can be decreased.
Superplasticizer
Zeta potential
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This article deals with the ways of mixing method for concrete with extremely low water-cement ratio (w/c) typical for ultra-high performance concretes. For this purpose, the mixture with w/c ratio of 0.2 and amount 6% superplasticizers of cement weight was used. In total 6 various mixing methods was tested, which differed in application of superplasticizers, mixing order or mixing length. Workability, electricity consumption during mixing and compressive and flexural strength after 28 days were examined. The performed experiments showed that workability can be increased by, for example, separate doses of superplasticizers and water or other mixing methods. Strength of concrete was identical for all produced mixtures, even though the total mixing time was shortened in two cases.
Superplasticizer
Mixing ratio
Water–cement ratio
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The article presents the results of researching efficiency of different modes of superplasticizer introduction in solution mixture with different consistency - from hard to plastic. The following methods of superplasticizer introduction into cement were researched: co-grinding of superplasticizer with cement, mixing cement with superplasticizer in dry state, introduction of superplasticizer into cement with mixing water, evaluation of water reduction effect of an additive depending on the methods of its introduction into cement and the time of determining its consistency. It is established that the most efficient method of superplasticizer introduction into plastic mixture is its co-grinding with cement.
Superplasticizer
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Polycarboxylate superplasticizer has the best application prospect in concrete engineering at present, this paper conducted test of working performances such as dispersibility and water-reducing rate to cement particle, slump, slump flow and its gradual loss of concrete by taking one modified high performance polycarboxylate superplasticizer as the study object. The study demonstrated that the modified high performance polycarboxylate superplasticizer solved the problem of sensitization of traditional high performance polycarboxylate superplasticizer to the mixing quantity of superplasticizer, it had good dispersibility to cement particle, and the optimum mixing quantity was 2.3%-2.9%, and the water-reducing rate was 25.6%-33.0%, this test proved that it had good water-reducing effect, which can significantly improve the fluidity and compressive strength of concrete if added with it.
Superplasticizer
Concrete slump test
Water–cement ratio
Water reducer
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Abstract The article presents a comparative analysis on the hydration of cement paste without superplasticizer and water/cement ratio of 0.35 and a cement paste with the same water/cement ratio but has in its composition 2% superplasticizer additive Glenium Sky 526. For characterizing the hydration process of cement paste, both mixtures were subjected to X-ray diffraction and thermogravimetry analysis, at 3, 7, and 28 days passed since the initiation of hydration process.
Superplasticizer
Thermogravimetry
Water–cement ratio
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Superplasticizer
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