• Corrosion Science and Technology
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• 제21권2호
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• pp.100-110
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• 2022

Corrosion of steel reinforcement is the most important mode of concrete structures damages. It strongly depends on the composition and physicochemical properties of the cementitious medium. The use of waste materials as lightweight aggregates in concrete is environmentally recommended in polluted environments such as marine and/or industrial atmospheres in order to reduce its porosity and ensure the requested protection of reinforcing steel. The present study investigated the effect of waste cork addition on corrosion resistance of steel rebar in mortar specimen prepared in the laboratory. The main objective of this study was to improve the corrosion resistance of reinforcing steel. Another objective of this study was to valorize this ecological product and preserve the environment. Results obtained from various electrochemical tests indicated that the presence of a fine cork powder substantially improved the corrosion resistance of steel in the mortar contaminated by chloride ions. This improvement was reflected by a notable decrease in corrosion current density and a shift of corrosion potential of the steel towards more noble values. Moreover, the presence of a fine cork powder in the mortar had no adverse effect on its mechanical properties.

• Advances in materials Research
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• 제11권4호
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• pp.299-330
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• 2022

This review article highlights the physical, mechanical, and chemical properties of coconut shells, and the fresh and hardened properties of the coconut shell concrete are summarized and were compared with other types of aggregates. Furthermore, the structural behavior in terms of flexural, shear, and torsion was also highlighted, with other properties including shrinkage, elastic modulus, and permeability of the coconut shell concrete. Based on the reviewed literature, concrete containing coconut shell as coarse aggregate with normal sand as fine showed the 28-day compressive strength between 2 and 36 MPa with the dried density range of 1865 to 2300 kg/m³. Coconut shell concretes showed a 28-day modulus of rupture and splitting tensile strength values in the ranges of 2.59 to 8.45 MPa and 0.8 to 3.70 MPa, respectively, and these values were in the range of 5-20% of the compressive strength. The flexural behavior of CSC was found similar to other types of lightweight concrete. There were no horizontal cracks on beams which indicate no bond failure. Whereas, the diagonal shear failure was prominent in beams with no shear reinforcements while flexural failure mode was seen in beams having shear reinforcement. Under torsion, CSC beams behave like conventional concrete. Finally, future recommendations are also suggested in this study to investigate the innovative lightweight aggregate concrete based on the environmental and financial design factors.

• 농업과학연구
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• 제25권2호
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• pp.271-277
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• 1998

본 연구는 폴리머와 인공경량 세골재 및 인공경량 조골재를 사용한 초경량 폴리머 콘크리트의 응력-변형특성을 구명한 것으로서, 이 연구를 통해 얻어진 결과를 요약하면 다음과 같다. 1. 동탄성 계수는 $1.514{\times}10^5{\sim}1.916{\times}10^5kgf/cm^2$로써 보통 시멘트 콘크리트의 48~96%정도이며, 인공경량 세골재의 양이 적을수록 크게 나타났다. 2. 정탄성계수는 $2.552{\times}10^4{\sim}4.386{\times}10^4kgf/cm^2$으로 보통 시멘트 콘크리트의 8~22%정도로 작게 나타났고, 포아손수도 보통 시멘트 콘크리트보다 작게 나타났다. 3. 응력-변형율곡선은 모든 배합에서 응력의 증가와 함께 증가하다가 최대하중에서 파괴된후 급격한 감소를 보였으며, 보통 시멘트 콘크리트보다 취성이 크게나타났다. 4. 최대응력하에서의 변형율은 P1에서 $6.975{\times}10^{-3}$으로 가장 크게 나타났고, P9에서 $1.600{\times}10^{-3}$으로 가장 작게 나타났으며, 인공경량 조골재의 양이 많을수록 작게 나타났다.