不同細度模數之細骨材對含氯混凝土工程性質影響之研究

Abstract

台灣地區地狹人稠，人口密度成長迅速，結構物邁向超高層大樓，國家經濟起飛也帶動了 公共工程建設蓬勃發展，使得砂石需求量日益增加。在本島四面環海，河川砂石量有限的 情況下，以海砂來取代河砂做為混凝土細骨材將是未來趨勢，但海砂蘊含的氯離子及本身 細度模數的因素對混凝土結構物卻存在著極大的殺傷力。因此，若從事相關之工程師在使 用海砂前能對含氯混凝土工程性質有一初步的膫解，應可對海砂作最有效之利用。本研究 使用不同細度模數之細骨材，並添加不同的氯離子含量，在相同水灰比的情況下，探討以 上變數對硬固混凝土抗壓強度、動彈性係數，及新拌混凝土中水溶性氯離子濃度隨時間之 變化和坍度的影響。相信能對含氯混凝土之工程性質與力學行為有更深一層的認識，對相 關之從事人員也希望有相當的助益。由研究結果顯示，混凝土之抗壓強度與動彈性係數隨 著細骨材細度模數增加而有增加的趨勢，氯離子在一定的添加量內將有助於強度的發展。 水溶性氯離子濃度隨時間的增加率依細度模數增加而有增高的現象，而混凝土之坍度在低 細度模數下較小，也將隨時間增加而變小。 Taiwan is a small sea-island with growing population，economy today.The econom ic growth makes the public-engineering develop rapidly.As a result,sand has be come an essential materially for this modern country.Based on above descriptio ns,the amount of river sand has been descreased.So，the replacement of river s and by sea sand as the fine aggregate will be the future trend.However,the chl oride ion contented in the sea sand and the factor of it*s fineness modulus(F. M.). are harmful for concrete structures.TheThis research utilized a number of F.M.，added in different concentration of chloride ion and used the same wate r-cement ratio to explore the influence by above vibrations to harden concrete *s compressive strength.In addition，the change of the concentration of chlori de ion in fresh concrete depends on the time frame, and slump are also discuss ed.I believe that this study will make people more understand about the engine ering and mechanic behavior of concrete with chloride ion ,also will be helpfu l for peopThe result of this study pointed out that the compressive strength a nd dynamic elastic modulus of concrete increased with the F.M. of fine aggrega te . And the certain amount of free chloride ion is helpful for the developmen t of strength . The increasing rate of concentration of free chloride ion depe nding on time will increase with the increasing of F.M..The slump of concrete under the low value of F.M. is lower and it also decreases when time increases .