結構物中所使用之水泥是一種高耗能之工業，生產過程中常對環境造成污染，若能尋求良好之替代性材料，以取代水泥之需求，則在環境保護與資源的開發、利用均有正面之幫助。本文主要以電弧爐煉鋼爐碴-還原碴為研究對象，並以完全取代水泥之概念為出發點，運用鹼活化技術提昇還原碴之活性，尋求新世代的膠結材料。根據以往研究指出，添加鹼活化劑之膠結材料，具有較佳之抗壓強度發展、耐久性及抵抗化學侵蝕能力等，但卻常伴隨著速凝、乾縮量過大及鹼質粒料等缺點。 本文主要針對鹼活化還原碴漿體收縮行為機理進行探討與抑制方 法研究。在抑制收縮試驗方面，採用的抑制方法包括添加輸氣劑、減水 劑、降低水膠比、提高養護溫度等。經試驗結果顯示，以添加輸氣劑與 提高養護溫度兩種方式所得之效果最好，但會致使抗壓強度略微下降。 在收縮機理分析方面，配合相關收縮理論與微觀分析，可證實鹼活化還 原碴漿體收縮行為與內部孔隙水發生毛細管冷凝之臨界半徑及孔隙半 徑為1.25 ~ 25 nm之孔隙含量比例有關；當此範圍之孔隙含量比例愈 高，還原碴漿體收縮愈明顯。 The production of cement is a highly energy-consuming industry. The seeking for an alternative material to take place of Portland cement is always a key research issue. The purpose of this study is to evaluate the potential of electric-arc furnace clinker produced in the steel-making processes – reductive slag as a binging material for concrete. The use of alkali-activator promotes the activity of slag and results in a cementing material of the new era. Previous researcher indicated the alkali-activated slag showed the better compressive strength, durability and resistance to chemical attack. However, some problems such as rapid setting, high shrinkage, and alkali-aggregate reactions may also present . This study aims at investigating the shrinkage mechanism of alkali-activated reductive slag and developing techniques in restraining the shrinkage of reductive slag. The proposed methods includes the addition of air entraining agent and/or water reducing agent, reduction of water/binder ratio, and elevation of curing temperature. The experimental results showed that the most effective methods were the addition of air entraining agent and the elevation of curing temperature. However, there may be detrimental effects on the compressive strength developments. It was found that the shrinkage of alkali-activated reductive slag has to do with the critical radius, which is defined as the radius of the pores where capillary condense occurs, and the radius of pore ranging from 1.25 to 25 nm. When the proportion of the pores whose radius in the range of 1.25 ~ 25 nm is higher, the shrinkage of alkali-activated reductive will also be higher.
