| 摘要: | 因應水泥工業高碳排放之挑戰及永續建材的需求，本研究探討以石灰石部分取代卜特蘭水泥所製成之低碳石灰石水泥（limestone cement, LC），應用於鋼筋混凝土中之工程性質，並結合二氧化碳加速養護（CO₂ curing，約 4 kgf/cm²、4 小時）技術，分析其對混凝土物理及力學性能之影響。
本研究設計三種水泥系統：傳統卜特蘭水泥（PC）、石灰石水泥（LC）、以及石灰石水泥搭配飽和石灰水拌合（HLC），分別於常規水養護與壓力鍋式碳養護（autoclave-type CO₂ curing）條件下進行比較。試體規格為直徑 50 mm、高度 100 mm 之圓柱體，試驗項目包含抗壓強度、彈性模數、吸水率測試，並輔以熱重分析（TGA）觀察碳酸鈣（CaCO₃）與氫氧化鈣（Ca(OH)₂）含量變化，以探討碳化反應效果。同時製作鋼筋混凝土試體，進行握裹與拉力裂縫控制試驗，以評估不同水泥系統對鋼筋–混凝土界面握裹力與裂縫發展行為之影響。
結果顯示，LC 與 HLC 系統於碳養護後皆展現顯著 CO₂ 吸收反應，TGA 分析亦驗證碳酸鈣含量明顯上升，證實碳化反應有效進行，促進孔隙結構緻密化，進而提升抗壓強度。彈性模數方面，碳養護試體普遍呈現剛性增加趨勢；吸水率亦明顯下降，反映材料致密性改善。握裹試驗中，HLC 系統因界面組成改變導致握裹力略微下降，而 LC 系統於鋼筋混凝土拉力試驗中則展現優異之延遲開裂能力與裂縫寬度控制效果，顯示其具優越的抗裂性與抑制裂縫發展潛力。
綜合評估，石灰石水泥搭配碳養護處理，除具 CO₂ 吸存與減碳效益外，亦可強化混凝土之整體力學性能與微觀結構穩定性，為低碳結構工程提供具實用性與永續性的材料替代方案。
;In response to the high carbon emissions of the cement industry and the growing demand for sustainable construction materials, this study investigates the engineering performance of low-carbon limestone cement (LC), produced by partially replacing ordinary Portland cement (OPC) with limestone, in reinforced concrete applications. An accelerated carbonation curing technique (CO₂ curing, approximately 4 kgf/cm² for 4 hours) was employed to evaluate its effects on the physical and mechanical properties of concrete.
Three cement systems were prepared: traditional OPC (PC), limestone cement (LC), and limestone cement mixed with saturated limewater (HLC). Cylindrical specimens (50 mm in diameter, 100 mm in height) were subjected to standard water curing and autoclave-type CO₂ curing. Experimental tests included compressive strength, modulus of elasticity, water absorption, and thermogravimetric analysis (TGA) to quantify the formation of calcium carbonate (CaCO₃) and the consumption of calcium hydroxide (Ca(OH)₂), revealing the extent of carbonation reactions. In addition, reinforced concrete specimens were tested for bond behavior and crack control performance to assess the rebar–concrete interface under different cement systems.
The results showed that LC and HLC systems exhibited significant CO₂ uptake after carbonation curing. TGA confirmed a substantial increase in CaCO₃ content, indicating enhanced carbonation and densification of the pore structure, which led to improved compressive strength. The modulus of elasticity also increased, reflecting enhanced stiffness, while water absorption significantly decreased, suggesting better compactness. In the bond strength test, the HLC system showed a slight reduction due to altered interface composition, whereas the LC system demonstrated superior crack control and delayed crack initiation in the tensile tests of reinforced concrete specimens.
Overall, limestone cement combined with carbonation curing not only offers effective CO₂ sequestration and emission reduction but also improves the mechanical properties and microstructural stability of concrete. It presents a feasible and sustainable alternative for future low-carbon structural engineering applications. |
