한국폐기물자원순환학회지 제 34권 제7호 (p.697-704)

CO2 노출 여부에 따른 알칼리 활성 슬래그 콘크리트의 압축강도와 화학적 특성 변화

Changes of Compressive Strength and Chemical Characteristics of Alkali-Activated Slag Concrete Before and After Carbon Dioxide Exposure
키워드 :
Blast-furnace slag,Alkali-activated slag concrete,Carbon dioxide exposure,Compressive strength,Chemical characteristics,Calcium-silicate hydration gels

초록

In this study, alkali-activated slag (AAS) concrete made with blast furnace slag (BFS) was investigated as a replacement for ordinary Portland cement (OPC) concrete for changes in the compressive strength before and after CO2 exposure and chemical reactions with CO2. Before CO2 exposure, the compressive strength of AAS concrete was found to be up to 21 MPa, which was higher than that of OPC concrete. Exposing AAS concrete to CO2 at 5,000 ppm for 28 days did not significantly change the compressive strength. In contrast, the compressive strength of OPC concrete decreased by 13% in the same conditions. In addition, AAS concrete had the highest CO2 capture capacity of greater than 50 g CO2/kg, while the CO2 capture capacity of OPC concrete was only 2.5 g CO2/kg. Rietveld analyses using XRD results showed that fractions of main calcium-silicate-hydration (C-S-H) gels on the surface of AAS concrete did not significantly drop after CO2 exposure; the C-S-H gel on the AAS concrete was continuously produced by reacting with the SiO2 produced after the reaction with CO2 and Ca(OH)2 inside the concrete, with the result that the compressive strength of AAS concrete did not change after CO2 exposure. Thus, AAS concrete can be applied to CO2-rich environments as both a stable construction material and a CO2 sequestrate agent.