低相對濕度環境下自養護混凝土最佳藥劑含量之研發與應用

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，依據試驗中所得之抗壓強度、體積改變、抗氯離子穿透能力及握裹拉力試驗，以探討自養護對混凝土之力學行為。 由研究結果顯示，整體表現最佳者為自養護藥劑含量1%組，養護3天以上其抗壓強度及體積改變量優於濕養護控制組，於齡期28天時自養護組養護3天以上其強度優於控制組飽和石灰水養護；而其抗氯離子穿透能力，濕氣養護5天以上即可優於濕養護控制組；自養護組無論空氣養護或濕氣養護7天其握裹應力均優於飽和石灰水控制組。 關鍵字：混凝土、自養護、濕氣養護、抗壓強度、RCPT、握裹

Curing is a very important step toward a more durable, higher strength, and less shrinkage concrete. Since sustainability has been the main stream to counteract global warming, supplementary cementitious materials, such as fly ash and slag, have been used widely to partly replace cement. This makes curing even more important.

This study is trying to improve the quality of concrete under low relative humidity with various self-curing admixtures(SCA) and dosages. The compressive strengths, volume change, RCPT, and bond strengths were investigated for concrete specimens with and without SCA. It is found that the optimum SCA dosage is 1% of cementitious material. A 3 days wet cure of specimens with SCA showed comparative strength of specimens without SCA under standard curing. For RCPT, a 5 day wet curing of specimens with SCA showed better resistance than standard cured specimens without SCA. The bond strengths of specimens with SCA, regardless of wet curing regime, are better than specimens without SCA and wet-cured for 28 days. The specimens with SCA demonstrated better bond strength compared to the control specimens at all curing regimes.

Keywords: concrete, self-curing, wet curing, compressive strength, RCPT, bond