• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.24 no.1
• /
• pp.27-32
• /
• 2014

This study analyzed the fundamental characteristics of concrete according to a ternary system mixing in order to reduce hydration heat of mass concrete and to improve early age strength. The results are as follows. The fluidity of unconsolidated concrete satisfied the target scope regardless of the binder conditions. When the replacement ratio between FA and BS increased, the slump of low heat-A mix and low heat-B mix increased, and air content was not affected by the change of binders. As for setting time, low heat cement mix had the fastest regardless of W/B, and high early strength low heat mix achieved 6 hours' reduction compared with low heat-B mix at initial set, and 12 hours' reduction at the final set respectively. As for the simple hydration heat, the low mix peak temperature was the highest and low heat-B mix had the lowest temperature. And high early strength low heat mix was similar with that of low heat-B. The compressive strength of hardened concrete had similar strength scope in all mixes except for low heat-B mix at early ages, and had unexceptionally similar one without huge differences at long-term ages.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.12 no.1
• /
• pp.17-24
• /
• 2024

The characteristics of low-heat concrete, mixed with ground blast furnace slag and ferronickel slag aggregate, were analyzed. Moreover, the applicability of this concrete for mass concrete in LNG storage tanks was examined. Initially, the study investigated the characteristics of fresh and hardened concrete. Subsequently, the temperature rising curve was obtained. Utilizing the obtained parameters from the curves, a series of thermal stress analyses for the LNG storage tank were conducted to assess the risk of cracking. The results confirmed that concrete mixtures incorporating ground blast furnace slag and ferronickel slag aggregate not only exhibited sufficient workability but also achieved a compressive strength of approximately 40 MPa within 28 days. Furthermore, the concrete demonstrated a lower terminal heat rise and a faster heat generation rate compared to low-heat Portland cement concrete. An analysis of thermal stress in various sections of the LNG tank validated a low risk of cracking.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.505-508
• /
• 2008

In this study, temperature increase and strength development of concretes with different types of cement were investigated to construct dam drop spillway. For this purpose, boxes of 1${\times}$1${\times}$1m size with 4 different concrete mixtures were made. The types of concrete were Type I cement concrete, fly ash cement concrete and two type concrete with ternary cement, respectively. The temperature at each point were monitored in these boxes. Based on the Box test, hydration analysis of slab of 2.0m thickness was carried out. This paper presents these experimental and analytical results.

• Journal of the Korea Institute of Building Construction
• /
• v.13 no.3
• /
• pp.218-226
• /
• 2013

Of construction materials, cement and steel are the representative material that carbon dioxide. to reduce carbon emissions in the use of these materials The purpose of this study is low heat type blended cement, which is manufactured using a amount of cement than ordinary low heat blended cement. Low heat blended cement, mixing ratio of 10%, was investigated hydration properties and adiabatic temperature of concrete. The study in order to activate the reaction mineral admixture, a separate source of CaO and $SO_3$ areneeded. gypsum and lime, it expected amount of cement, low-carbon low-heat blended cement could reduce the hydration heat concrete than currentlyused low heat blended cement.

• Clean Technology
• /
• v.28 no.4
• /
• pp.278-284
• /
• 2022

This study presents an excellent planar heater based on low-dimensional composites. By optimizing the ratio of 1D carbon nanotubes (CNT) and 2D MXene (Ti₃C₂T_X), it is possible to create a planar heater that has superior electrical conductivity and high heat generation characteristics. Low-dimensional composites were prepared by mixing CNT paste and MXene solution with eco-friendly waterborne polyurethane (WPU). In order to find the optimal mixing ratio for the MXene-CNT-WPU composites, samples with MXene to CNT weight ratios of 3:1, 1:1, 1:3, 1:7, and 1:14 were investigated. In addition to these different weight ratios, 5 wt% WPU was equally applied to each sample. It was confirmed that the higher the weight ratio of CNT, the lower the sheet resistance and the higher the heating temperature. In particular, when the MXene-CNT-WPU planar heater was fabricated by mixing MXene and CNT at a weight ratio of 1:7 and 1:14, the heating temperature was higher than the heating temperature of a CNT-WPU planar heater. These characteristics are due to the optimized mixture of the 1D materials (CNT) and the 2D materials (MXene) causing the formation of a flat surface and a dense network structure. The low-dimensional composites manufactured with the optimized mixing ratios found in this study are expected to be applied in flexible electronic devices.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.05a
• /
• pp.25-26
• /
• 2015

In this study, we test the 3 properties low hydrated heat as binder, and also utilized the hydrated heat disparity construction method to decrease the cracks of the mass concrete caused by hydrated heat. The result showed by using the two methods narrowly decreased the cracks. And we ensured that during the mass concrete pouring, the cracks caused by hydrated heat could be reduced by utilizing the new construction method.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.215-216
• /
• 2009

Recently, the application of SCC (Self Consolidation Concrete) gets more necessity, in order to solve the problem of quality control, noise, etc. In this study describe the optimum mix proportion and the experience of cast in place of the SCC in main structure of underground RC box.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.677-680
• /
• 2008

The surface of particles was energetically modified by inter-grinding OPC and BFS in vibration mill for improvement of the early strength and low-heat evolution of concretes. BFS was pre-grinding in ball-mill to 2535(BS2) and 3245 $cm^2/g$(BS3), in blaine surface area. The inter-grinding time in vibration mill was changed from 10 minutes to 30 minutes. And Mixing ration of BFS to OPC was changed in 60, 70, 80%. After inter-grinding, the change of specific surface area, particle size distribution, hydration heat of cement and compressive strength of mortar were measured. As the result of comparison test with LHC, it was found that the mixture and inter-grinding time satisfying the value of over 100% of compressive strength for 7 days and under 170J/g of heat of hydration for 72 hours. and it was confirmed that the possibility of low heat slag cement utilizing blast furnace slag(BS2, BS3) with the low fineness in high volumes.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.249-252
• /
• 2008

In recent large-scale structures, as mass concrete type structure is frequently applied to the building, temperature crack due to hydration heat needs to be considered. Since a volume change is internally or externally restricted in a mold after placing concrete, temperature crack of mass concrete takes place. By this reason, the reduction method to control this crack is required. In this study, low heat mixture and hydration heat difference is used to execute the analysis of hydration heat, considering the changes of heat transfer coefficient according to curing conditions and block placement of mass concrete. For the analytical modelling, original portland cement and concrete of low heat mixture are placed in the upper and lower payer, respectively. A convection boundary condition is fixed because mass concrete of block placement is characterized by the difference of mold form and curing condition. Through the analysis results considering the changes of low heat mixture, block placement, and heat transfer coefficient, we check out the temperature and stress distribution and analyze the temperature crack reduction effect.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.11a
• /
• pp.55-57
• /
• 2012

In this study, the field applicability on reducing the heat of hydration of mass concrete by using the hydration heat difference method is analyzed with the following summary. As a result of applying the hydration heat difference method by using low heating combination, the temperature difference between the central part and the surface part of mass material was reduced, and as a result of visual observation, there was no showing of cracks by the hydration heat on the upper surface part. Therefore, the cracking index of the field to apply this method was shown to be approximately 1.57 with very little crack occurrence probability of less than 3%.