高鋁水泥耐久性研討

The Research on the Durability of High Alumina Cement

高鋁水泥是一種快硬早強之水硬性膠凝材料，其主要礦物組成為鋁酸一鈣和二鋁酸一鈣等鋁酸鹽是鋁酸鹽水泥系統中最重要的一種商品，適用於軍事工程、緊急搶修工程、冬季嚴寒施工及要求早強之特殊工程。同時其耐高溫、抗硫酸鹽及海水腐蝕性能好，水化時生成鋁膠使漿體結構緻密具有抗滲透性，而且對含碳酸以及含稀酸也有很好的穩定性，但對鹼性溶液之耐蝕性不佳，且由於晶型轉換而影響其長期強度，故不宜作永久性承載之結構工程。故本文將探討其一般性質及耐久性問題，以供工程界正確選用此類材料之參考。

High alumina cenent is an rapid hardening (high early strengh) hydraulic cement. Its principal mineralogical phase is monocalcium aluminate (CA) and Calciam bialummate (CA2) and secondary phases are C12A7, αA(alamina), C2S,Ferrites, C4AF, etc. It is used for refractory concrete and emergency repair, especially in cold weather. It does not release free lime on hydration with water, also show excellent resistance to chemical attack. The Composition of hydration product shows a time temperature dependency the low temperatare hydration product hexagonal phase CAH10and C2AH8 is thermdynamically unstable, and it tends to convert to a more stable compound cubic phase C3AH6. This Con version will cause an increase in porosity and loss in strength, thus the resistance to atmosphere carbonation and steel corrosion in concrete would be reduced. Therefore it is not recommended for structural use. In this paper the typical properties will be review and discussed. It is hoped these information is helpful for industry in utilizing of this material.