高水灰比波索蘭混凝土耐久性之研究

Abstract

本研究乃參考 ACI 配比設計，設計出三種不同高水灰比混凝土（W/C=0.75、0.90、1.15），且添加飛灰及爐石粉等波索蘭材料取代 20% 的水泥量；在 28 天水中養護完成後，施以大氣養護及人工海水乾溼循環加速作用，以便探討其中種種之差異；而本研究乃採力學試驗、化學分析及電化學試驗的方法，以了解波索蘭材料對高水灰比混凝土的影響。 研究結果顯示：抗壓強度試驗、劈裂強度試驗乃動彈性模數試驗結果皆顯示出，添加波索蘭材料試體晚期強度及動彈性模數較高，且乾溼循環中之試體，動彈性模數比大氣中試體來的高；氯離子濃度試驗顯示，大氣中試體氯離子的濃度隨齡期增加而下降，且乾溼循環中由於海水的侵入，氯離子濃度皆隨齡期增加而上升，而且水灰比愈低之試體氯離子濃度亦較低；鋼筋腐蝕電位試驗及混凝土電阻試驗結果，大氣中試體皆未達腐蝕程度，而乾溼循環中之試體，鋼筋已經產生腐蝕，且隨齡期的增加腐蝕更為嚴重，添加波索蘭材料之試體其鋼筋腐蝕電位值及混凝土電阻值皆高於未添加波索蘭材料試體，所以對鋼筋的腐蝕，能提供一個較佳的保護環境。

The research takes ACI code, design to three different high water-cement ratio concrete (W/C=0.75, 0.90, 1.15) .We add fly-ash and slag to replace 20percent cement. Treat them in air curing and dry-wet cycle acceleration to find their different after 28 days water curing. This research uses mechanical test, chemical method and D.C to understand the influence of Pozzolans for high water-cement ratio concrete. The research result points out that add Pozzolans the compressive strength, dynamic modulus of elasticity, and modulus of rupture will be higher in the later period. Besides the dynamic modulus of elasticity in the dry-wet cycle will be higher than in the air curing. The experiment in the content of Cl- points out that the content of Cl- decrease in air curing as time increase, but in dry-wet cycle acceleration becrease the seawater permeate, the content of Cl- increase as time increase. When the W/C lower the content of Cl- lower. The experiment of Potential and the Resistence points out that yhe steel will be not corrsive in air curing, but the steel have corrsived in dry-wet cycle acceleration and will be as heavy as time increase. Add Pozzolans in dry-wet cycle the Potential and Resistence will be higher than that not add Pozzolans, and can provide a good protective environment for steel.