自養護混凝土力學性質與收縮之發展

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。 本文研究測試不同之新配方自養護藥劑，利用自養護藥劑的保水效果，達到較節能之養護方式為目標。本試驗分兩階段，先以固有自養護藥劑成分，搭配新測試之藥劑，依照不同比例分別取10g放置於∅90mm x 15mm之培養皿中，使用四位數高精度電子秤，觀測藥劑在90天內分別於相對濕度40%與相對溼度95%之環境下的重量變化，探討何種藥劑於吸水及放水下成效較佳。將較佳藥劑取總粉體之1%分別加入傳統混凝土及自充填混凝土中，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，自養護新配方藥劑試驗以藥劑七之比例成效為佳，而取1%總粉體量藥劑製成自養護混凝土。濕氣養護 14 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7 天之強度即可達設計強度 8成，自養護組於齡期 90 天之抗氯離子穿透能力(RCPT)與電阻率接近甚至優於基準組，兩組配比皆以濕氣養護 14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 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 test different new blended Self-Curing admixtures proportions (SCA) to achieve better conservation and energy-saving way that based on water retention of SCA. The experiment was divided into two parts. The first part was to test weight change of new SCA with past SCA and mixed with each other in different proportions and environments. The second part was to use the better optimum SCA separated added 1% into traditional concrete and self-compacting concrete (SCC) in order to test the workability, mechanical properties, volume stability and durability. Observing the relationship between standard curing and the way of curing, compare with each other and sort out each variables, then we can make regression analysis. The admixtures results show that the ratio seven of SCA is the best optimum, then we take 1% of it to make curing concrete specimens. The 14 day wet curing specimens with SCA are very close or even better than standard curing without SCA in mechanical properties and durability. The 7 day strength with SCA can be up to 80% then the design strength, and the specimens with SCA at 90 days, the ability for rapid chloride permeability test (RCPT) are very close or even better than the specimens without SCA. These two proportions can just take 14 days through wet curing with SCA can reach the effect of standard curing without SCA.