• Title/Summary/Keyword: $CO_2$촉진 양생

Search Result 8, Processing Time 0.031 seconds

Investigation of Early-Age Concrete Strength Development Using Hardening Accelerator (경화촉진제를 사용한 콘크리트의 초기강도 발현 특성 검토)

  • Kim, Gyu-Yong;Kim, Yong-Ro;Park, Jong-Ho
    • Journal of the Korea Concrete Institute
    • /
    • v.28 no.3
    • /
    • pp.309-316
    • /
    • 2016
  • In this study, performance of hardening accelerator types which promote setting and hardening of cement has been reviewed in order to develop early age strength of concrete with compressive strength of 21~27 MPa after examination of strength development of the concrete at early age according to curing temperature and unit cement(binder) content. As results, soluble mineral salt showed better hardening acceleration effect than organic salt in the scope of this study. Also, hydration reaction accelerating effect of $C_3S$ by Soluble mineral salt is effective on development of early age compressive strength and it was shown that the Pt's hydration reaction accelerating effect was the best. Construction duration reduction can be expected by securing compressive strength for prevention of early aged freezing damage in 25hour-curing time under curing temperature at $15^{\circ}C$. Also, it was shown that compressive strength of specimen cured at $5^{\circ}C$ was similar with plain specimen cured at $10^{\circ}C$. Therefore, it is expected that fuel costs and carbon dioxide can be reduced when the same construction duration is considered.

Fundamental Characteristics of CO2-cured Mortar with Varied Rates of Blast Furnace Slag Fine Powder Substitution (고로슬래그 미분말 치환율에 따른 이산화탄소 양생 모르타르의 기초 물성)

  • Ryu, Ji-Su;Jang, Kyung-Su;Na, Hyeong-Won;Hyung, Won-Gil
    • Journal of the Korea Institute of Building Construction
    • /
    • v.24 no.1
    • /
    • pp.11-21
    • /
    • 2024
  • This research elucidates the fundamental properties of carbon dioxide (CO2)-cured mortar as influenced by varying substitution rates of blast furnace slag fine powder. The findings indicate that CO2 curing enhances the formation of calcium carbonate (CaCO3), contributing to pore reduction and the early development of strength. While calcium hydroxide (Ca(OH)2) plays a more pivotal role in the primary development of strength compared to CaCO3, an increase in the substitution rate of blast furnace slag fine powder results in reduced production of Ca(OH)2. Nonetheless, the maintenance of strength through CaCO3 formation is observed even after the depletion of Ca(OH)2, suggesting that the required performance can be sustained post-exposure to the atmosphere following CO2 curing. It is noted that substitution rates exceeding 50% lead to performance deterioration due to CO2, highlighting the necessity for careful adjustment of the substitution ratio.

An Experimental Study on the Carbonation Depth of Cement Paste Using Carbonation Reaction Accelerator (탄산화 반응 촉진제를 이용한 시멘트 페이스트의 탄산화 깊이에 관한 실험적 연구)

  • Seok-Man Jeong;Wan-Hee Yang;Dong-Cheol Park
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.11 no.4
    • /
    • pp.349-354
    • /
    • 2023
  • This study wa s conducted a s pa rt of ma ximizing the use of ca rbon dioxide by a pplying CCU(Ca rbon Ca pture, Utiliza tion) a mong technologies for reducing CO2 in the cement industry. In a carbon dioxide curing environment, changes in carbonation depth and changes in basic physical properties by age due to the mixing of carbonation reaction accelerators were usually targeted at Portland cement paste. In addition, in order to check the fixed amount of CO2 in the concrete field, a thermal analysis method was applied to evaluate CaCO3 decarbonization at high temperatures. As a result of the evaluation, it was confirmed that the carbonation depth in the cured body significantly increased due to the incorporation of CRA in the carbonation depth diffusion performance. In addition, it was confirmed that the weight reduction rate increased by 23.8 % and 40.77 %, respectively, compared to Plain, in the order of curing conditions for constant temperature and humidity and curing conditions for carbonation chambers, so it was confirmed that the amount of excellent CaCO3 produced by the addition of CRA increased as the concentration of CO2 increased.

Experimental Study on Accelerated Carbonation Characteristics of OPC Paste for CSC-Based Low Carbon Precast Concrete Products (CSC 기반 저탄소 콘크리트 2차제품 제조를 위한 OPC 페이스트의 촉진탄산화 특성에 관한 실험적 연구)

  • Yoon, Jun-Tae;Kim, Young-Jin;Sim, Sang-Rak;Ryu, Dong-Woo
    • Journal of the Korea Institute of Building Construction
    • /
    • v.24 no.3
    • /
    • pp.285-295
    • /
    • 2024
  • This study investigated the impact of accelerated carbonation on Ordinary Portland Cement(OPC) paste that had undergone steam curing at 500℃·hr. Two carbonation environments were examined: atmospheric carbonation(1atm, 20% CO2) and pressurized carbonation(5atm, 99% CO2). Chemical analysis using X-ray diffraction(XRD) and Fourier-Transform Infrared spectroscopy(FT-IR) were conducted, along with physical characterization via scanning electron microscopy(SEM) and compressive strength testing. Results indicated that atmospheric carbonation with 20% CO2 concentration significantly densified the internal microstructure of the OPC paste, leading to enhanced compressive strength. Conversely, pressurized carbonation at 5atm with 99% CO2 concentration resulted in rapid densification of the surface structure, which hindered CO2 diffusion into the sample. This limited the extent of carbonation and prevented the improvement of physical properties.

Physicochemical Properties of Cement Paste Containing Mg(OH)2 Cured by CO2 curing Method (CO2 양생을 이용한 Mg(OH)2 혼입 시멘트 페이스트의 물리화학적 특성)

  • Chen, Zheng-Xin;Lee, Han-Seung
    • Journal of the Korea Institute of Building Construction
    • /
    • v.18 no.3
    • /
    • pp.203-210
    • /
    • 2018
  • Corrosion of the rebar is one of the main factors affecting the durability of reinforced concrete in the world which lead to the failure of the reinforced concrete structures. In this research, a new method of fixing $CO_2$ is practiced to improve the carbonation resistance of the concrete. Brucite($Mg(OH)_2$), a kind of common $CO_2$ fixation materials, was added into ordinary Portland cement paste. Samples containing 0%, 5%, 10%, and 15% $Mg(OH)_2$ were exposed to an accelerated carbonation curing regime with 20% concentration of $CO_2$, 60% relative humidity, and a temperature of $20^{\circ}C$ until tested at 3d, 7d, 14d and 28d. After 28d of $CO_2$ accelerated curing, in the paste containing $Mg(OH)_2$, magnesian calcite was detected by SEM-EDX. Meanwhile, the paste containing $Mg(OH)_2$ exhibit the better pore distribution than ordinary Portland cement paste and the compressive strength of the cement paste containing $Mg(OH)_2$ were more than 50Mpa.

An experimental study on carbonation resistance of Mg(OH)2 mixed cement paste (Mg(OH)2 혼입 시멘트 페이스트의 탄산화 저항성에 관한 실험적 연구)

  • Chen, Zheng-Xin;Lee, Yun-Su;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2017.05a
    • /
    • pp.165-166
    • /
    • 2017
  • Corrosion of reinforcement is the main factors affecting the durability of reinforced concrete in the world which lead to the failure of structures of reinforced concrete buildings. In this research, mixed brucite(Mg(OH)2) into ordinary portland cement paste in ratio of 5, 10 and 15% as a kind of CO2 fixation material. Samples were exposed to an accelerated carbonation enslavement of 20% CO2 concentration, 60% relative humidity, and a temperature of 20℃ until tested at 3d, 7d, 14d and 28d. After 28d CO2 accelerated curing, in the paste containing MH megnesian calcite was found by XRD and SEM-EDX. Meanwhile, paste containing Mg(OH)2 exhibit the better pore distribution than ordinary portland cement paste and relatively good compressive strength.

  • PDF

Effect of Cement Contents and Combinations of Accelerators on Strength Development of Concrete Cured at 10℃ (10℃ 양생조건에서 단위 시멘트량 변화 및 경화촉진제의 복합사용에 따른 강도발현 성능에 관한 연구)

  • Song, Young-Chan;Lee, Tea-Gyu;Kim, Yong-Ro;Seo, Chi-Ho
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.6 no.2
    • /
    • pp.94-99
    • /
    • 2018
  • The purpose of this study is to investigate the effect of combinations of different accelerators mixed on the early age strength development of concrete of 21 to 27MPa in the curing temperature of $10^{\circ}C$ compared with existing early strength agent. The present study was assessed the early strength development of combinations of three different accelerating admixtures with early strength type agent comparing to single accelerating admixture with early strength type agent. As a result of this study, the effect of $CaBr_2+NaSCN+DEA$ combination on strength development showed better than $CaBr_2$ or NaSCN alone with early strength type agent. Therefore, we observed that concrete using $CaBr_2+NaSCN+DEA$ combination with early strength agent was achieved 5MPa 12hours earlier than use of $CaBr_2$ or NaSCN alone.

Material and Behavior Characteristics of Lightweight Embankment for Road Constructed on Soft Ground (연약지반에 시공된 도로용 경량성토체의 재료 및 거동특성)

  • Yea, Geu-Guwen;Lee, Yong-Jae;Kim, Hong-Yeon;Yoon, Gil-Lim;Han, Sang-Hyun
    • Journal of the Korean Geosynthetics Society
    • /
    • v.17 no.2
    • /
    • pp.41-49
    • /
    • 2018
  • The purpose of this study is to fabricate a full scale road embankment using lightweight air foamed soil as a soil material on soft ground and to investigate its material characteristics and behavior in order to promote dredged soil utilization and minimize ground improvement. As a result of the laboratory test of the onsite mixed samples, the total unit weight of the specimens decreased almost linearly until curing 28 days. In particular, the total unit weight after 28 days of curing was reduced to about 81% of the slurry state before curing, which will be useful in the formulation of similar native soil materials in the future. The unconfined compressive strength began to decrease with the 14th day of curing as shown in the previous study. When the cement content is increased, the strength decreases sharply at a small strain change after the occurrence of the maximum compressive strength, and the maximum strength is exhibited in a range of a smaller axial strain than normal range. The settlement at the surface layer of the ground due to the lightweight embankment was about 1 / 2.75 of the soil embankment and was in agreement with the unit weight ratio (1 / 2.7) of the embankment materials. This indicates the cause and effect of the settlement due to the difference in self weight of the embankments. Also, the difference in settlement between soil and lightweight embankment increased with increasing depth. This shows that the difference in the point at which the settlement is terminated is clear. The ground horizontal displacement under the lightweight embankment was about 15~20% smaller than that of the soil embankment and the depth of occurrence was also 4.5~5.0m shallower in the lightweight embankment.