海洋環境下高性能混凝土之耐久性探討

The Durability of High Performance Concrete under Marine Environment

本文係探討高性能混凝土在海洋環境下之物理、化學及力學性質之行為，並評其耐久性能。計劃之初，規畫以高性能混凝土取代一般港灣設施所需求之中、低強度之傳統混凝土，於拌製過程中進行混凝土漿體之坍度、坍流度之量測，製作標準圓柱試體，進行各項基本性質試驗。為長期觀測其耐久性能，製作大尺寸之鋼筋混凝土試驗牆曝放於大氣中，每日定時施以海水噴灑表面，進行乾濕循環加速試驗。牆內埋置有各種偵測元件，監測項目包括有漿體之電阻、溫度、濕度及鋼筋腐蝕電位、腐蝕電流密度等長期性之變化。初期試驗結果顯示，高性能混凝土具有甚佳之工作度、高強度、高電阻係數、低透水係數、低電滲量（小於1000庫倫）。試驗牆曝放一年六個月後，內部之鋼筋腐蝕電位仍處於-100 mV (Cu/ CuSO4)，鋼筋腐蝕電流密度甚小，後續腐蝕變化仍持續監測中。

In the study, the behaviors of high performance concrete (HPC) on their physical, chemical and mechanic properties were under investigated; long term durable performance was also evaluated. At the first stage of the project, HPC was designed to instead of traditional ordinary Portland concrete (OPC) at medium to low compressed strengths required for marine concrete structures. At mixing concrete paste, the index of workability such as slump and flow test were measured and compared for both HPC and OPC. Standard cylindrical specimens were cast for further fundamental qualities analysis. Large scale of reinforced concrete walls of HPC and OPC were made and exposed at outdoors sprayed by seawater. Inside the concrete walls, there were seniors embedded for long-term monitoring on concrete resistance, temperature, moisture, rebar potential and corrosion current density. Test results depicted that HPC has very excellent workability, high compressive strength, high concrete resistance, low permeability, and low charge passed (less than 1000 coulombs). Rebar potentials of concrete walls were at -100mV (by Cu/CuSO4), and their corrosion current densities were also low after one and half years exposed.