PURPOSES : In this experimental study, the resistance of blended cement concrete containing air-cooled slag (AS) and water-cooled slag (WS) to freeze–thaw action was investigated. For comparison, the durable performance of ordinary Portland cement (OPC) concrete exposed to a similar damage environment was also evaluated. METHODS : Based on the ASTM C 666 standard, the relative dynamic modulus of elasticity, mass ratio, surface electric resistivity, and compressive strength of blended cement concrete specimens were periodically measured and compared with those of OPC concrete to evaluate the durability of concrete exposed to the freezing-thawing environment. In addition, microstructural characteristics of deteriorated concrete parts were evaluated using scanning electron microscopy (SEM) and energy dispersive spectroscopy techniques to detect products formed by freeze–thaw action. RESULTS : It was found that the resistance of blended cement concrete containing AS and WS to freeze–thaw action was significantly better than that of OPC concrete. Furthermore, the SEM results revealed the frost damage of OPC concrete, owing to the formation of thaumasite. CONCLUSIONS : The application of AS in concrete can effectively improve the durability of concrete, particularly in freeze–thaw environments.

PURPOSES : This paper presents the experimental results of tests conducted on concrete produced with air-cooled (AS) and water-cooled (WS) ground blast-furnace slag exposed to multi-deterioration environments of carbonation and scaling. METHODS : Carbonated and uncarbonated concrete specimens were regularly monitored according to the ASTM C 672 standard to evaluate the durability of concrete exposed to both scaling and combined carbonation and scaling conditions. Additionally, mechanical properties, such as compressive strength, flexural strength, and surface electric resistivity, were analyzed. RESULTS : It was found that concrete specimens produced with AS and WS had a beneficial effect on the mechanical properties because of the latent hydraulic properties of the AS and WS mineral admixtures. Moreover, carbonated concrete showed good scaling resistance in comparison to uncarbonated concrete, particularly for concrete produced with AS and WS. CONCLUSIONS : The improved scaling resistance of carbonated concrete showed that AS is a suitable option for binders used in cement concrete pavements subjected to combined carbonation and scaling.

PURPOSES : Durability of concrete is traditionally based on evaluating the effect of a single deterioration mechanism such as freezing & thawing action, chloride attack, carbonation and chemical attack. In reality, however, concrete structures are subjected to varying environmental exposure conditions which often results in multi-deterioration mechanism occurring. This study presents the experimental results on the durability of concrete incorporating air-cooled slag(AS) and/or water-cooled slag(WS) exposed to multi-deterioration environments of chloride attack and freezing & thawing action. METHODS: In order to evaluate durable performance of concretes exposed to single- and multi-deterioration, relative dynamic modulus of elasticity, mass ratio and compressive strength measurements were performed. RESULTS: It was observed that multi-deterioration severely affected durability of concrete compared with single deterioration irrespective of concrete types. Additionally, the replacement of cement by AS and WS showed a beneficial effect on enhancement of concrete durability. CONCLUSIONS : It is concluded that resistance to single- and/or multi-deterioration of concrete is highly dependent on the types of binder used in the concrete. Showing the a good resistance to multi-deterioration with concrete incorporating AS, it is also concluded that the AS possibly is an option for concrete materials, especially under severe environments.

전기로 환원슬래그는 가장 처리하기 곤란한 부산물이였지만, 공기급냉에 의해 수화 활성도를 높임으로서 자원으로서 활용하는 것이 가능하다. 본 연구팀은 용융상태의 슬래그를 공기 급냉하여 비드상으로 응고시킨 후, 이를 일정한 크기의 미분으로 분쇄한 후 적절한 첨가제를 사용하여 국내의 시장에서 요구되는 속경성과 강도를 만족하는 제품을 개발하였다.

본 논문은 제강슬래그를 잔골재 대체재로 콘크리트에 활용할 경우 유리석회의 다량 함유로 인한 팽창성 때문에 콘크리트용 골재로서의 사용이 제한되고 있어 제강슬래그를 급냉시켜 유리석회의 함유량를 크게 낮춘 급냉제강슬래그를 잔골재로 활용한 콘크리트의 특성에 관한 연구이다. 따라서 급냉제강슬래그의 대체율 및 잔골재율을 달리하여 제작한 콘크리트 시험체의 슬럼프로스시험, XRD 및 SEM분석에 따른 수화특성, 재령에 따른 압축강도 시험, 길이변화시험 및 급속염소이온침투시험결과를 비교 고찰하여 급냉제강슬래그의 적정 대체율 및 잔골재율을 도출하였다.