Long-Term Accelerated Carbonation Behavior and Shrinkage of Ground Granulated Blast Furnace Slag-Based and Cellulose Fiber-Reinforced Cementitious Composites

This study investigated the long-term performance of slag-based fiber-reinforced cementitious composites containing ground granulated blast furnace slag (GGBS) and cellulose fiber (CF) under CO₂ and air curing.Samples were divided into three groups: Ordinary portland cement (OPC), GGBS, and GGBS-CF.Results showed that GGBS and GGBS-CF experienced mass loss under both curing conditions, whereas OPC lost mass in air but gained mass under CO₂ curing.In terms of shrinkage, GGBS-CF exhibited the lowest shrinkage in air curing, while OPC showed the lowest shrinkage under CO₂ curing.For carbonation resistance, OPC had a shallower carbonation depth than both GGBS and GGBS-CF, indicating slower CO₂ penetration.At 91 days under air-curing conditions, GGBS-CF and GGBS achieved compressive strengths 31.0%and 28.5% higher than OPC, respectively.A similar trend was observed in flexural strength, with GGBS-CF showing a 33.9% increase, while GGBS remained comparable to OPC.Under CO₂ curing, OPC exhibited improved mechanical properties, whereas both slag-based mixtures showed reduced strength, suggesting greater alteration of slagderived hydrates than portlandite-rich systems.TGA revealed a pronounced carbonate decomposition peak at 700-800 °C, and XRD confirmed increased carbonate formation after CO₂ exposure.These findings provide guidance for optimizing CO₂ curing in sustainable cementitious materials.