The effect of bare electrode in the dielectric constant, $\varepsilon^*(\omega)$, of conductive dielectric materials including space charges was investigated by using three types of electrodes, bare, insulated and partially insulated electrode for the frequency range of $10^4-10^6$Hz at the environmental temperature of T=30℃. The results obtained for de-ionized wate, natural water and cement paste during initial setting, showed that the dielectric constant measured with the bare electrode was explicitly different from that of measuring by the insulated electrode during initial setting of cement paste. These facts represents that the dielectric constant at the electrode masks the that of the specimen(bulk) containing space charges. The dielectric constant and conductivity of cement paste was obtained by the curve-fitting of $\varepsilon'$ and $\varepsilon$ by using insulated electrode, which indicated well the change of viscosity and the amount of ions in the cement paste. The comparison of dielectric constant and heat evolution rate obtained by using the insulated electrode with the work of McCarter and Ashar by the bare electrode, indicated that the dielectric value measured by bare electrode was 10 times as large as that of the insulated electrode. The mechanical properties improved greatly after 7 days hydration under compressive loading. The improvement in density, ultrasonic velocity and modulus of cement paste hydrated under compressive loading was attributed due to the higher degree of compaction resulting from low pore density."
공간전하를 포함하는 물질에대해 bare electrode를 사용하여 측정한 유전상수는 시험편의 유전상수와 많이 달랐다. 이러한 사실은 탈이온수, 자연수, 세멘트 반죽의 유전상수를 세가지 형태의 전극(bare electrode, insulated electrode, partially insulated electrode)을 사용하여 측정함으로서 보여졌다. Insulated electrode를 사용해서 세멘트의 수화과정 동안 유전상수와 전기 전도도는 얻어졌고, 사용한 전극의 영향을 알기위하여 MacCarter와 Afshar의 bare electrode를 사용하여 얻은 값과 비교되었다. Bare electrode를 사용하여 얻은 유전상수는 10배 정도 큰 값을 나타내었다. 수화과정 동안 압축력의 영향은 초기의 수화과정을 빨리 진행시켰고 강도와 밀도를 크게 증가시켰다.
