自養護藥劑於含礦物摻料之水泥砂漿與混凝土研究

Abstract

養護的目的為避免水分從混凝土中過度蒸散，且達到充分的水化反應，提升混凝土性質。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，常使用礦物摻料取代部分粉體，但礦物摻料之卜作嵐反應其水化反應時間晚於水泥，故更突顯養護之重要性。 本文研究測試不同配比下，利用自養護藥劑的效果與礦物摻料在晚期之卜作嵐反應特性，以提升新拌與硬固混凝土各項性質，且達到較節能之養護方式為目標。本試驗分兩階段，先以固定水膠比0.38之礦物摻料─水泥砂漿於不同配比下，添加自養護藥劑，養護3天後，藉重量損失、抗壓強度與收縮試驗，探討於何種配比下成效較佳。篩選配比製成混凝土，作工作性測試、重量體積穩定性、力學試驗與耐久性試驗，觀察幾種養護方式與標準養護之基準組間關係與比較，統整各項變數後，作迴歸公式預測。 研究結果顯示，礦物摻料─水泥砂漿配比以爐石量30%~50%，飛灰量0%~10%之配比，綜合三項試驗結果成效為佳。而自養護混凝土(C5S5與C7S3)濕氣養護3天即有相當接近甚至超越標準養護基準組的結果(力學性、耐久性)，其自養護組齡期3天之強度已超越設計強度280 kgf/cm2，自養護組於齡期90天之抗氯離子穿透能力(RCPT)與電阻率皆優於基準組，兩組配比皆以濕氣養護3天即可達到標準養護之成效。

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 later than the hydration reaction of cement. This makes curing more important to guarantee the effectiveness of pozzolans. This study use different pozzolan replacements with the addition of SCA to test the fresh and hardened concrete’s properties and to achieve more energy-efficient concrete. The experiment was divided into two phases. The first used w/b 0.38 of mineral admixtures-cement mortar in different proportions with SCA, and after curing, the weight loss, compressive strength and shrinkage were tested to investigate the best combinations of replacement ratio and SCA. The second phase was to select the mix proportion which show better performances and then use them in producing concrete and test the workabilty, mechanical properties, volume stability and durability. Several curing regimes were employed for comparison. And multi-variable regression analysis was executed. The results show that the optimum replacement ratio for slag is 30-50% and fly ash is 0-10% of total cementitious material in mineral admixtures-cement mortar. The 3 day wet curing specimens with SCA (C5S5 and C7S3) are very close or even better than standard cured specimens without SCA in mechanical properties and durability. The 3 day strength with SCA has exceeded the design strength and reaches 280 kgf/cm2, and the specimens with SCA at 90 days, the resistance to chloride ion penetration (RCPT) and resistivity are better than the specimen without SCA. Proportions use 3 day wet curing with SCA can reach the performances of standard cured specimens without SCA.