• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.433-442
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• 2021

In this study, the properties of no-fines polymer concrete with different polymer binder contents were evaluated. The polymer concrete was formulated using a polymeric binder (unsaturated polyester resin), fly ash, and recycled coarse aggregate (60%) and crushed coarse aggregate (40%). The polymeric binder content (4.0-6.0wt.%) was used as an experimental variable because it dramatically affects both the cost-effectiveness and material properties. The results showed that the density, compressive strength, flexural strength both before and after exposure to freezing and thawing increased as the polymer binder content increased, while the absorption, void ratio, permeable voids, coefficient of permeability, and acid resistance (mass loss by acid attack) decreased as the polymeric binder content increased. In particular, even though the void ratio was 18.4% and the water permeability coefficient was 7.3mm/sec, the compressive strength and flexural strength were as high as 38.0MPa and 10.0MPa, respectively, much more significant than those of previous studies. Other properties such as absorption and acid resistance were also found to be excellent. The results appear to be rooted in the increased adhesion of the binder by adding a cross-linking agent and the surface hydrophobicity of the polymer.

• Journal of Conservation Science
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• v.36 no.5
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• pp.339-350
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• 2020

This study attempted to apply a hybrid technology that integrated mineral-based fillers and water-repellent agents to control the efflorescence that results from the use of inorganic binders, for the conservation treatment (surface finishing) of cultural heritage materials made up of stone. Herein, different types of mixing ratios of a filler (silica fume 3.4%) and a water repellent (silane-siloxane 1%) were selected for fabricating the inorganic binder, and it was determined that the ratio selected by weight is effective in controlling efflorescence substances. In addition, it was identified that the inorganic binder with the mixing ratio resulted in a higher compressive strength than the standard (20MPa), and the water permeability resistance was high with low water absorption. The result of ion elution from the bilder showed that a smaller number of ions was observed to affect the efflorescence (directly and indirectly) as compared to that of the control group, which was considered to be relatively stable.

• Computers and Concrete
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• v.24 no.2
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• pp.151-158
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• 2019

The sustainable development principle of replacing natural resources with renewable material is an important research topic. In this study, waste LCD (liquid crystal display) glass powder was used to replace cement (0%, 10%, 20% and 30%) through a volumetric method using three water-binder ratios (0.47, 0.59, and 0.71) to make cement mortar. The compressive strength was tested at the ages of 7, 28, 56 and 91 days. The test results show that the compressive strength increases with age but decreases as the water-binder ratio increases. The compressive strength slightly decreases with an increase in the replacement of LCD glass powder at a curing age of 7 days. However, at a curing age of 91 days, the compressive strength is slightly greater than that for the control group (glass powder is 0%). When the water-binder ratios are 0.47, 0.59 and 0.71, the compressive strength of the various replacements increases by 1.38-1.61 times, 1.56-1.80 times and 1.45-2.20 times, respectively, during the aging process from day 7 to day 91. Furthermore, a prediction model of the compressive strength of a cement mortar with waste LCD glass powder was deduced in this study. According to the comparison between the prediction analysis values and test results, the MAPE (mean absolute percentage error) values of the compressive strength are between 2.79% and 5.29%, and less than 10%. Thus, the analytical model established in this study has a good forecasting accuracy. Therefore, the proposed model can be used as a reliable tool for assessing the design strength of cement mortar from early age test results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.186-187
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• 2022

The purpose of this study was to give fluidizing properties to non-sirtered cement made using by-products that can replace Portland cement by using a fluidizing agent. Blast furnace slag, C-type fly ash, and F-type fly ash were used for non-sirtered cement, and sand was used for aggregate. The amount of fluidizing agent used was fixed at 1%, and the water-cement ratio (W/C) was different by setting the binder blending ratio of the non-sintered cement differently, and the fluidity test and flow were compared. As a result of the experiment, when the flow standard was 170mm when the fluidizing agent was used, the fluidizing properties were shown at an average water-cement ratio (W/C) of 36%. Through this study, it was confirmed that the fluidizing properties appeared when the fluidizing agent was used in non-sintered cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.877-880
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• 2008

Recently the press and institute recognized fly ash as it had excellent performance. Its research and applications are on the rise largely as a substitute for cement. On the contrary, it is in a situation that the regulation of high quality fly ash remains at a low level. Accordingly, this study was to establish 8000 class of fineness of fly ash and three levels of substitute like 15%, 3 0%, and 45% in order to analyze the replacement ratio and effect of water-binder ratio for fly ash that affected the properties of ternary system concrete. As a result of experiment by planning water-binder ratio for two levels like 40% and 50%, it increased the fluidity in a fresh state, and it decreased the air content. This study has found out the setting acceleration and reduction of heat of hydration. As for the strength property in a set state, this study has shown the tendency of being equal or higher in age 28 days.

• Computers and Concrete
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• v.21 no.2
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• pp.149-156
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• 2018

This paper investigated the influence of binary and ternary blends of mineral admixtures in self-compacted mortar (SCM) on the fresh, mechanical and durability properties. For this purpose, 25 mortar mixtures were prepared having a total binder content of $640kg/cm^3$ and water/binder ratio between 0.41 and 0.50. All the mixtures consisted of Portland cement (PC), fly ash (FA) and silica fume (SF) as binary and ternary blends and air-entrained admixture wasn't used while control mixture contained only PC. The compressive and tensile strength tests were conducted for 28 and 91 days as well as slump-flow and V-funnel time tests whilst freeze-thaw (F-T) resistance and capillary water absorption tests were made for 91-day. Finally, in general, the use of SF with FA as ternary blends improved the tensile strength of mortars at 28- and 91-day while the use of SF15 with FA increased the compressive strength of the mortars compared to binary blends of FA. SCM mixtures with ternary blends had lower the sorptivity values than that of the mortars with binary blends of FA and the control mixture due to the beneficial properties of SF while the use of FA with SF as ternary blends induced the F-T resistance enhancement.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.34-39
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• 2017

Under a corrosive environment, electrodes that are applied in the water-treatment system need not only very high electrochemical activity for fast reactions, but also high durability for cost saving. Therefore, the fabrication condition of iridium electrodes was examined to produce a more durable iridium electrode in this study. Tantalum was selected as a binder to enhance the durability of the iridium electrode. Investigation of the weight ratio between the catalyst and the binder to improve electrochemical activity was performed. Also, to compare the effect of the different coating amounts of the catalyst, the results of CV (Cyclic Voltammetry) and EIS (Electrochemical Impedance Spectroscopy) were discussed. Furthermore, an ALT(Accelerated Lifetime Test) was designed and applied to the electrodes to determine the conditions for highly durable electrode fabrication.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.593-599
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• 2013

The unrestrained shrinkage strain of alkali-activated (AA) slag concrete was examined and compared with design equations specified in code provisions and empirical equations proposed by Yang et al. The main parameters investigated were the water-to-binder ratio (W/B), unit water content and fine aggregate-to-total aggregate ratio (S/a). Test results revealed that shrinkage strain of AA slag concrete is nearly proportional to the W/B ratio, whereas its time function is independent of the W/B ratio. The shrinkage strain of AA slag concrete increased significantly when the unit water content is above $185kg/m^3$, whereas it is marginally affected by the S/a ratio. The design equation of ACI 209 considerably overestimates the shrinkage behavior of AA slag concrete, whereas CEB-FIP equation tends to underestimate the shrinkage at the age more than 28 days. The empirical equation of Yang et al. is in better agreement with test results, showing that values of mean and standard deviation of error coefficients obtained from each specimen are 016 and 0.07, respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.104-112
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• 2019

The material properties of the 3D printing cement composite mortar were evaluated, and the performance range in which printing was possible was calculated using the void ratio in a fresh state as a single index. As a results of the tests, as the water-binder ratio (W/B) increased, the mortar flow value increased and the density and strength decreased. As the sand-binder ratio (SS/B) increased, the mortar flow value decreased. However, strength and density increased and decreased up to a certain SS/B. As admixture-binder ratio (Ad/B) increased, mortar flow value, density, and strength decreased. These trends make it difficult to mix-design to meet the target performances of 3D printing mortars, represented by extrudability and buildability. The value of mortar flow increased proportionally with the void ratio, while the density and strength apparently decreased as the void ratio increased. This indicates that void ratio can be utilized as a single index for controlling the material properties in the design of mortar mixtures. It was found that mortar mixture could be printed by a 3D printer when the void ratio was in the range from 0.6 to 0.7. This was verified by printing a mortar which has the void ratio of 0.634. The mortar was produced with the mixture design of W/B 35.0%, SS/B 60.0%, and Ad/B 0.1%. Further research applying diverse admixtures is needed to improve the quality of 3D printing output mortars.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.367-370
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• 2005

In this study, air meter method and capacitance measurement method to apply economically at quality control of ready-mixed concrete among various unit water content measurement technique was selected. Then, it was evaluated estimating performance of unit water content according to the change of water-binder ratio and unit water content. Also, it was examined influence about error occurrence of unit water content by change of properties of used materials. Finally, based on this study, it was proposed fundamental data to utilize measurement technique of unit water content to quality control. of ready-mixed concrete in construction field.