交流阻抗法透過微小刺激訊號和大範圍頻率能反應出混凝土材料內部微結構在不同頻率下的阻抗行為，配合等效電路擬合所得的電路元件值，根據其個別所代表的物理意義，可以瞭解混凝土配比的變動所帶來的微結構變化。本研究之目的為探討以交流阻抗法檢測混凝土材料的粗粒料效應，實驗設計為使用固定配比之水泥砂漿，改變粗粒料含量、尺寸以及種類，試體於飽和石灰水中養護56天，將試體取出表面擦乾，以面乾內飽和態進行交流阻抗實驗，將得到的阻抗數據繪製成Nyquist Plot，並選用Song等效電路模型進行擬合，觀察試體整體電阻率與等效電路模型電路元件值的趨勢，探討混凝土中的粗粒料含量、尺寸及種類改變對交流阻抗法可得之各參數之間的關係。
研究結果顯示，由於粗粒料相較於水泥砂漿而言，其電阻率極高，所以添加粗粒料相當於在電流傳導路徑中增加障礙物，降低電流可傳導之截面積，增加電流傳導路徑的曲折度，使得粗粒料含量增加，電阻隨之提高，又粗粒料取代大量砂漿體積，使得固液界面數大減，儲存電荷能力降低，故粗粒料含量增加，電容隨之下降。相同含量不同粒徑的粗粒料，粒徑較小者於空間分布較廣，電流傳導時遇到的機率較高，又粒徑小者的曲折度較粒徑大者大，所以粗粒料粒徑小者電阻較粗粒料粒徑大者高，又粒料粒徑會影響界面過渡區(ITZ)的性質，小粒徑粗粒料的ITZ厚度較薄，孔隙率較低較緻密，儲存電荷能力會較大粒徑粗粒料者低，故使用小粒徑粗粒料的試體電容會較使用大粒徑粗粒料的試體電容來的低。

The Electrical Impedance Spectroscopy (EIS) is a powerful method to reveal the microstructure of materials. The fitting parameters contained in the equivalent circuit can reflect the change of microstructure. In this study, the influence of the content, size and type of coarse aggregates was investigated. Concrete specimens were made by cement mortar and several amounts of coarse aggregates with fixed size and type in a single specimen. After EIS test, we plotted the Nyquist plots and fitted the test results with Song’s model. Then we discussed the coarse aggregates effects via the trends of the bulk resistivity and the values of electronic components.
The results show that variations in coarse aggregate content and size do have the influence on concrete impedance, but type was observed no effects on it. The inclusion of coarse aggregates means adding obstacles in the conductive path due to its high resistivity, so the resistance increases. Also, the increasing of aggregate content means the decreasing of the amount of cement mortar, it will remarkably reduce the amount of solid-liquid interfaces, and it eventually decreases the capacitance. The effects of coarse aggregate size are the smaller the aggregates are, the higher the resistances are, because of the wider spatial distribution and higher tortuosity. And the smaller the aggregates are the lower the capacitances are. It’s probably because of the nature of ITZ, the smaller-size aggregates has thinner and denser ITZ than the larger one, so leading to the lower capacitances.

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