低相對濕度環境下自養護混凝土之研發與應用

Abstract

混凝土於澆置完成後須進行養護工作，良好的養護能使混凝土提 高水密性、強度、體積穩定性、耐久度等性能。而今基於環保與節能 減碳需求，皆會使用卜作嵐材料取代部分粉體，但卜作嵐材料其水化 反應時間晚於水泥，若養護不當將使卜作嵐材料無法於後期進行水化 反應，致使混凝土的硬固性質有所缺陷。 本研究目標為提高自養護混凝土 在低相對濕度環境下的各項硬 固性質；試驗中採用自養護藥劑製作混凝土試體，並於澆置完成後以 不同養護方式與不同養護時間與傳統養護比較，依據試驗中所得之水 分重量損失、體積改變、試體強度與抗氯離子穿透能力，以探討混凝 土之自養護行為。 由研究結果顯示，自養護組養護3 天之水分重量損失優於濕養護 控制組，自養護組養護3 天以上之體積改變量優於濕養護控制組，自 養護組之試體強度於1 天齡期即可達設計強度9 成，自養護組養護3 天以上之抗氯離子穿透能力等同於飽和石灰水養護28 天，代表養護 僅需3 天即可達傳統濕治養護14 天之成效。

Curing is essential to achieve a good concrete with low permeability, high strength, high volume stability, and durability. Nowadays, the sustainability is a very important issue and reduction of carbon dioxide is required. Pozzolanic materials are added to concrete for this purpose. Moisture is needed for pozzolanic reactions and this makes curing even more important. This research studies the effect of hardened concrete of self-curing concrete(SCC) under various curing regime and low RH. The weight loss, volume change, strengths, and RCPT were studied. It is found that even under the low RH, the self-curing admixture can still function. The weight loss and volume stability of SCC with 3 days wet curing is less than the control concrete, which is 28 day wet cure. The SCC can reach 90% of targeted strength at 1 day. The RCPT of SCC with 3 days wet cure is similar to that of 28 days standard curing concrete. This results demonstrate that the SCC with 3 day wet cure can have properties of 14-28 days standard curing and SCC is very helpful to the quality of concrete.