• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.365-371
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• 2020

In this study, in order to recycle the stems of opuntia cactus discarded after harvesting the fruit, the cactus stems were powdered and applied as a cement-based admixture. The powder of cactus stem was mixed into the mortar, and its effect on the fresh properties and strength of the mortar was studied. The results were compared with the properties of mortars produced by mixing with a retarder sugar and a viscosity agent methyl-cellulose, which are conventional saccharide-based admixtures. Based on the test results, the cactus stem powder did not clearly show the effect as a retarding agent, whereas the flow and the air content were similar to those of the mortar mixed with methyl-cellulose. This indicated that the cactus stem powder can be used as a viscosity agent. It was found that the strength of the mortar tended to increase when the mixing ratio of the cactus stem powder was lower than 0.3%.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.793-800
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• 2006

This paper reports test results to assess the influence of superplasticizers and different admixture on the flow and compressive strength development of cementless mortar using developed hwangtoh binder. Test specimens were classified into four groups: series for I the mixing ratio of superplasticizers, series II for a kind and replacement level of admixtures according to the variation of water/hwangtoh binder ratio, series III for the specific surface area and replacement level of ground granulated blast-furnace slag and series IV for the replacement level of powered superplasticizer agent developed to improve slump loss of concrete. The proper replacement level of each admixture is proposed for enhancement the flow and compressive strength of the hwangtoh binder mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.541-544
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• 2008

Recently, due to the increase of high-rise buildings construction, many researches for making harden of concrete earlier and remove of forms faster are being performed to reduce construction period. The purpose of this study is to analysis which mixing condition and curing temperature of early strength concrete. Porperties of concrete by the different factors, such as the type of active admixtures, mineral admixtures, curing temperature, the amount of binder, etc. Through the test of concrete using the different type of admixture, PC type was more excellent than PNS type admixture. The concrete Strength remarkably will be able to confirm that decreases from temperature below 12$^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.337-340
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• 2008

As the Ready-mixed Shotcrete using Powdered Polymer Dispersion, Shotcrete Matrix as totally shotcrete gel that a part of second binder in Shotcrete materials is dense. Also, Ready-mixed Shotcrete is showed the decreasing Rebound and rising Durability. Therefore, it is possible that Ready-mixed Shotcrete for High-Strength and High-Waterproof can apply to the Powdered Polymer Dispersion.

• Journal of the Korea Institute of Building Construction
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• v.18 no.3
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• pp.259-266
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• 2018

In recent years, the early strength of concrete is important in order to shorten the time of form removal at the construction site. The purpose of this study is to analyze the moment of form removal as investigating the amount of cement contents and the physical properties and strength of the concrete according to types of admixture in the curing temperature of $10^{\circ}C$ for concrete of 21 to 27 MPa. As a result, it was found that compressive strength of concrete could not be secured 5 MPa by 36 hours even if the amount of cement contents were increased to $360kg/m^3$ with plain admixture. Also, it was confirmed that the strength improvement rate was excellent when using the accelerating agent with polycarboxylic acid type, and the moment of compressive strength of 5 MPa was estimated at 30 hours.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.285-290
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• 2023

Poly-lactic acid (PLA) is the most promising polymer in additive manufacturing as an alternative to acrylonitrile butadiene styrene (ABS). Since it is produced from renewable resources such as corn starch and sugar beets, it is also biocompatible and biodegradable. However, PLA has a couple of issues that limit its use. First, it has a comparatively low glass transition temperature of around 60 ℃, such that it exhibits low thermal resistance. Second, PLA has low impact strength because it is brittle. Due to these problems, scientists have found methods to improve the crystallinity and ductility of PLA. Polyethylene glycol (PEG) is one of the most studied plasticizers for PLA to give it chain mobility. However, the blend of PLA and PEG becomes unstable, and phase separation occurs even at room temperature as PEG is self-crystallized. Thus, it is necessary to investigate the optimal mixing ratio of PLA-PEG at the molecular scale. In this study, molecular dynamics will be conducted with various ratios of L-type PLA (PLLA) or DL-type PLA-PEG (PDLA-PEG) systems by using BIOVIA Materials Studio.

• Magazine of the Korea Concrete Institute
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• v.9 no.3
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• pp.149-156
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• 1997

In order to improve compressive strength of cement mortar, powder admixture(FAS) was mmufactured by mixing fly ash. Il-anhydite and silica hume, and superplasticizer was used for the control of fluidity reduction with the use of this admixture. Cement was substituted by 10, 20wt% of FAS respectively. At W/S = 0.40, the fluidity of' cement paste substituted by PAS was decreased. NSF and NT-2 were very effective fbr the control of fluidity reduction. As the particle size of U -anhydrite was fine, the fluidity of cement mortar was increased. The fluidity reduction of cement mortar substituted by 10wt% of FAS was controlled. The compressive strength of cement mortar substituted by 10wt% of FAS showed higher. value than that of 20wt%, expecially specimen(C1) substituted by 10wt% of $\gamma$ had the highest compressive strength value.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.624-627
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• 2004

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it according to its capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high Quality aggregate. Therefore, For solving the problems we apply to method of packaged dry combined materials for concrete using dried materials. That is to say that it is a kind of making into an instant. In this study, There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate's absorption following the rate of adding water, for using existing materials.

• Journal of the Korea Institute of Building Construction
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• v.5 no.2 s.16
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• pp.131-138
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• 2005

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it in order to do capability at every fields. We have been close to demand new rapability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high quality aggregate. Therefore, For solving the problems we apply to a packing method for using dried materials. That is to say that it is a kind of making into an instant. In this study. There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate's absorption following the rate of adding water, for using existing materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.153-156
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• 2004

Most concrete is recently made of an aggregate which is properly absorbed. and carried in it in order to do capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high quality aggregate. Therefore. For solving the problems we apply to a packing method for using dried materials. That is to say it is a kind of making into an instant. In this study. There is a purpose to present fundamental data. comparing and analyzing a phenomenon about aggregate's absorption following the rate of adding water. for using existing materials.