自養護自充填混凝土工程性質之研究

Abstract

養護之目的在於避免水分從混凝土中過度蒸散，且達到充分的水化反應以提升混凝土之工程性質。隨著現今人類環保意識抬頭、材料技術進步及經濟性的需求下，常使用卜作嵐材料取代部分膠結材料，但卜作嵐反應相較於水泥水化需時較長，養護之於混凝土在時代的演進下更顯其重要性。 本研究測試不同水膠比之自養護藥劑效果與卜作嵐材料在晚期與自養護藥劑之卜作嵐反應作用，以提升自充填混凝土之各項工程性質、較經濟之養護方式、合適的應用自養護藥劑於自充填混凝土為目標。本試驗分別採高性能混凝土常用之水膠比區間以了解自養護藥劑於各工程性質的適用性，澆置0.32、0.36、0.40、0.44、0.48五組水膠比的試體，並分別對五組試體採以濕氣養護2天、濕氣養護5天、飽和石灰水養護28天等三種養護方式養護，試體完成養護後存放於大氣環境下（相對溼度70%），待齡期達1-7、14、28、56、90天時測試其各項工程性質。 測試項目有抗壓強度試驗、劈裂抗張強度試驗、鋼筋拉拔試驗（握裹強度）、混凝土水分重量損失試驗、混凝土收縮試驗、含鋼筋混凝土收縮試驗、快速氯離子穿透試驗、表面電阻率試驗，觀察與比較不同養護方式與基準組間關係，以統整各項試驗數據做迴歸軟體分析。 結果顯示自養護自充填混凝土各項工程性質試驗隨水膠比與養護條件有所變異，在本研究中將以各項工程性質做為判斷自養護自充填混凝土的養護效果，並分析得自養護藥劑的水膠比適用性範圍、判斷較經濟的養護齡期，以期對自養護藥劑的使用方法、作用方式有更深入的研究與了解。

The purpose of curing is to prevent excessive evaporation of water from the concrete to achieve full hydration to improve quality of the concrete. With today’s environmental consciousness of human being, the progress of material technology and economic needs, the use of mineral admixtures (slag, fly ash) often replace part of cement, but pozzolanic reaction of mineral admixture is in the later age than the hydration reaction of cement. This makes curing more important to guarantee the effectiveness of pozzolans. This study use different water cementitious ratio with the addition of SCA to test the fresh and hardened concrete’s properties, including mechanical properties, volume stability and durability. Several curing regimes were employed for comparison. And multi-variable regression analysis was executed. It is found that different w/cm ratios exhibit different performince in terms of strength, shrinkage, water loss, RCPT, and surface electrical resistance. In addition, it is also found that steel rebar can effectively restrain the shrinkage, and better for higher steel ratio.