• Journal of the Korea Institute of Building Construction
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• v.21 no.4
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• pp.269-279
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• 2021

Palm Oil Fuel Ash(POFA) has been widely used to replace Portland cement to enhance the mechanical properties and durability of concrete. However, it reduces the workability of concrete due to the high content of unburnt carbon and its angular shape requiring the usage of superplasticizer to ensure a proper flowability. In this study, effects of different types and dosage of superplasticizer on the early mechanical and hydration properties of cement paste containing micro-POFA were evaluated using mini-slump test, early compressive strength, TGA, XRD, and SEM. The results indicated that the flowability of cement paste containing micro-POFA reduced as the replacement ratio of micro-POFA increased. As the dosage of superplasticizer increased, the flowability was also increased. In addition, the usage of superplasticizer reduced the early compressive strength, and the strength decreased with an increase in the dosage of superplasticizer. It was confirmed that superplasticizer hindered the formation of C-S-H leading to a relative increase in the formation of Ca(OH)₂.

• Computers and Concrete
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• v.5 no.6
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• pp.559-572
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• 2008

The effects of fly ash and superplasticizer (SP) on workability of concrete are quite difficult to predict because they are dependent on other concrete ingredients. Because of high complexity of the relations between workability and concrete compositions, conventional regression analysis could be not sufficient to build an accurate model. In this study, a workability model has been built using artificial neural networks (ANN). In this model, the workability is a function of the content of all concrete ingredients, including cement, fly ash, blast furnace slag, water, superplasticizer, coarse aggregate, and fine aggregate. The effects of water/binder ratio (w/b), fly ash-binder ratio (fa/b), superplasticizer-binder ratio (SP/b), and water content on slump were explored by the trained ANN. This study led to the following conclusions: (1) ANN can build a more accurate workability model than polynomial regression. (2) Although the water content and SP/b were kept constant, a change in w/b and fa/b had a distinct effect on the workability properties. (3) An increasing content of fly ash decreased the workability, while raised the slump upper limit that can be obtained.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.35-36
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• 2016

Recently, with the increasing demand of high performance of concrete, the mix design of concrete mixture has became low water-to-binder ratio with high binder content. To compensate these trend of mix design, high range water reducer, or superplascizier has been invented to achieve high flowable concrete. Although this superplasticizer provides favorable workability based on its dispersing action on the components of concrete mixture, it has an limitation of decreasing viscosity of the mixture, and thus it is difficult to secure sufficient workability for high performance concrete mixtures with high binder content. To improve the workability of concrete with high viscosity, recently, low-viscosity type superplasticizer was introduced, and in this research, a fundamental properties of low-viscosity type superplasticizer is evaluated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.148-149
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• 2022

The use of high-strength grout applied for facility foundations and bridges has recently been expanding in offshore wind farm. Wind farm in offshore require bearing capacity for horizontal loads such as wind, waves, and earthquakes. In order to improve the bearing force of the base part, sufficient fluidity and a certain strength should be ensured so that the high-strength grout is densely charged in the narrow space of the connection part. Therefore, in this study, changes in fluidity and strength according to the ratio of PC-based superplasticizer mixed in high-strength grout were measured. As a result, as the ratio of the superplasticizer increased, fluidity increased and strength decreased. However, the strength did not decrease when the ratio of superplasticizer was above a 0.005. Therefore, it was confirmed that the fluidity change was remarkable when a 0.005 ratio of PC-based superplasticizer were added.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.813-816
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• 2008

Polycarboxylate-type superplasticizer is widely used for producing self-compacting and high-strength concrete and improving concrete durability. This paper discusses the influence of molecular structure of polycarboxylate-type superplasticizer on the fluidity and the rate of heat liberation of ordinary Portland cement paste. The fluidity of cement paste was increased by addition of polycarboxylate-type superplasticizer. The arrival time up to the maximum rate of heat liberation was increased by addition of polycarboxylate-type superplasticizer. The fluidity and the arrival time up to the maximum rate of heat liberation were more influenced by addition of polycarboxylate-type superplasticizer having shorter grafted chain than that having longer grafted chain.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.68-75
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• 2017

The study investigates the effects of the content and using method of chemical admixtures such as superplasticizer and viscosity modifying admixture on the fluidity, bleeding ratio, volumetric change and compressive strength of the grout in order to provide basic data for the development of high-quality grout for prestressed concrete. It appeared that the combination of superplasticizer and viscosity modifying admixture decreased the fluidity of grout with small content of superplasticizer. On the contrary, Grout used more than 0.1% of superplasticizer appeared to have significant effect on the improvement of the fluidity. On the other hand, bleeding of grout reduced according to increasing the content of viscosity modifying admixture. Superplasticizer with less than 0.05% had practically no effect on the reduction of bleeding, whereas superplasticizer with more than 0.1% appear to have significant effect on the reduction of bleeding. Also the combination of superplasticizer with 0.15% and viscosity modifying admixture with 0.15% resulted in satisfactory fluidity accompanied with fair reduction of bleeding and shrinkage of the grout.

• Journal of the Korea Institute of Building Construction
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• v.3 no.1
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• pp.115-122
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• 2003

In order to analyze liquidity change according to increasing the charge of superplasticizer, we inputted charges by dividing into six steps, 0% through 1.25%; at the same time, to observe liquidity change according to the change of charge-time, we carried out the experiment applying 30-minute intervals, i.e. at beginning of mixing, 30, 60 and 90 minutes. The results are below. 1) According to increasing the charge of superplasticizer, the liquidity of concrete was enhanced, however, when inputted 1.25%, a little segregation was occurred, which allowed us to make a conclusion that concrete performance would be deteriorated due to this segregation. 2) When we inputted 1.25% of superplsticizer, steady liquidity features were shown regardless of the charge-time of concrete, which allowed us to make a conclusion that this input would be the best for liquidity performance considering only liquidity features. 3) After analyzing the dynamical features of liquid concrete, the result showed that there was not significant effect on revelation of compressive strength. We concluded form this result that there was no influence on the stripping-time of a mold form. 4) When we charge superplasticizer in concrete more than 1%, we, in advance, should clearly judge the concrete performance required during constructing in site, as it were, the compressive strength or liquidity etc.; furthermore, we had better decide a charge and input-time of superplasticizer to meet the required performance.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.387-393
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• 2010

To improve concrete quality one of the most widely used chemical admixtures is polycarboxylate type superplasticizer. Unlike lignosulfonate and naphthalene-sulfonate, it has high dispersion property and excellent sustainable dispersion property for cement and concrete. Thus, polycarboxylate type superplasticizer has been widely used as a high-performance water reducing admixture together with silica fume in high-performance concrete and other applications for the dispersion of high-strength concrete over 100 MPa. However, even though there have been many studied on the dispersion of concrete by the structure of polycarboxylate type superplasticizer, there have a few studied that clarified the relationships between its rheological properties and microstructure properties in the early hydration behavior of ordinary portland cement. To investigate the correlations between the rheological properties and microstructure of cementitious materials with polycarboxylate type superplasticizer, this study experimented on the rheology, pore structure, heat evolution, and consistency in early hydration as well as on the compressive strength by early dispersion characteristics.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.743-748
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• 2002

Properties of concrete have been tested with Polycarboxylic superplasticizers based on Malein Anhydride Acid Polymer synthesized in a laboratory, to decide the proper formulation for concrete. Ready-mixed concrete has been placed at field with the chosen formulated Polycarboxylic superplasticizer. The superplasticizer showed quite a performance in workability retention and strength development of concrete at laboratory test and field application.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.638-644
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• 1999

Workability time of superplasticized concrete is maintained generally for 30-60 minutes only. Therefore it is of great advantage for the concrete producer to use a high range water reducer which provides an extended slump life. Recently slump retentive srperplasticizer has been developed. Concrete mixing tests were done to know slump, setting, air content, bleeding and hardening characteristics of concrete using slump retentive superplasticizer. With slump retentive superplasticizer, high quality concrete was produced and slump loss of concrete was reduced in big way, making long transportation time possible as a practical alternative to on-site addition.