In the present study, the effects of electrodes type (copper, steel or CFRP) and design (plate or mesh) on electrical stability of conductive cement as exposed to various weathering conditions were investigated. To fabricate these composites, multiwalled carbon nanotube and carbon fiber were added to the cement composites by 0.6 and 0.4% by cement mass. Seven different types of electrodes were embedded to the samples, and their electrical stability was examined during the curing period. In addition, the fabricated samples were exposed to water ingress and cyclic heating conditions. Then, the compressive strength of the samples was evaluated to observe the interfacial bonding between the cement paste and electrodes. Based on the experimental results, it was found that the samples showed different electrical stability even their mix proportion was same. Thus, it can be concluded that the type and design of the electrodes are important in measuring the electrical properties of the conductive cement composites. Specifically, an improved electrical stability of electrodes is required when they are exposed to various weathering conditions.

The use of recycled materials, such as the fine recycled aggregate made from concrete waste and carbon fiber (CF) product of industrial waste, for the manufacture of conductive recycled mortars (CRM), transforms the mortar base cement normally made with cement:sand in a sustainable multifunctional material, conferring satisfactory mechanical and electrical properties for non-structural uses. This action provides ecological benefits, reducing the use of natural fine aggregates from rivers and the amount of concrete waste deposited in landfills resulting from construction waste. In this investigation the effect of the addition of CF on electrical properties in hardened, wet and dry state, electric percolation in dry state and fluidity of the wet mixture of a cement based CRM was evaluated: fine recycled aggregate: graphite powder, CRM specimens with dimensions of 4 × 4 × 16 cm. were manufactured for 3, 7 and 28 days of age and sand/cement ratios = 1.00, graphite/cement = 1.00, water/cement = 0.60 and CF = 0.1, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% compared to the weight of cement. The results demonstrated the effect of the addition of CF in CRM, reducing fluidity of the mixtures due to the opposition generated by its physical interaction of CF with recycled sand or recycled fine aggregate and graphite powder (GP), in its case, placing the electric percolation percolation at 0.30% and 0.45% of CF for CRM with and without GP, respectively. Increases in electrical conductivity (EC) without the presence of GP are defined by the contact between the CF and the conductive paths formed. In contrast, with the presence of GP, the EC is defined by the contact between the CF and the GP simultaneously, forming conductive routes with greater performance in its EC.

Pollution of chloride ion-reinforced concrete can trigger active corrosion processes that reduce the useful life of structures. Multifunctional materials used as a counter-electrode by electrochemical techniques have been used to rehabilitate contaminated concrete. Cement-based pastes added to carbonaceous material, fibers or dust, have been used as an anode in the non-destructive Electrochemical Chloride Extraction (ECE) technique. We studied the performance of the addition of Carbon Fiber (CF) in a cement-graphite powder base paste used as an anode in ECE of concretes contaminated with chlorides from the preparation of the mixture. The experimental parameters were: 2.3% of free chlorides, 21 days of ECE application, a Carbon Fiber Volume Fraction (CFVF) of 0.1, 0.3, 0.6, 0.9%, a lithium borate alkaline electrolyte, a current density of 4.0 A / m2 and a cement/graphite ratio of 1.0 for the paste. The efficiency of the ECE in the traditional technique using metal mesh as an anode was 77.6% and for CFVF of 0.9% it was 90.4%, with a tendency to increase to higher percentages of the CFVF in the conductive cement-graphite paste, keeping the pH stable and achieving a homogeneous ECE in the mass of the concrete contaminated with chlorides.

탄산화가 고전도성 시멘트 복합재료의 전기전도도에 미치는 영향에 대해 실험적으로 확인 하였다. 탄소나노튜브(carbon nanotube, CNT)가 혼입된 페이스트형 및 모르타르형 시멘트 복합재료를 설계하였으며, 제조된 시편을 촉진탄산화 환경에 노출 시켰다. 반년간의 노출 후 확인한 결과 시멘트 복합재료의 전기전도도가 급격하게 감소한 것을 확인 할 수 있었다. 이 특성은, 전도성 시멘트 복합재료를 콘크리트용 센서로 사용했을 때, 탄산화에 의해 복합재료의 전기전도도가 변화할 수 있음을 고려해야 한다는 증거임과 동시에, 이 복합재료가 탄산화 센서로 사용될 수도 있다는 것을 의미한다. 본 논문은 본 연구 진의 기존논문 Lee et al.(2019)를 요약한 것이다.

전기전도도가 높은 시멘트 복합재료에 염소가 침투했을 경우 그 자체의 전기전도도가 어떻게 바꾸었는지를 실험적으로 확인 하였다. 시멘트 복합재료의 전기전도도 확보를 위해 탄소나노튜브(carbon nanotube, CNT) 및 탄소섬유(Carbon fiber)를 사용하였다. 염소의 침투가 시멘트 복합재료에 미치는 영향을 알아보기 위해 1) 염화나트륨을 배합 시 적당량 혼입하는 방법과 2) 염화나트륨 수용액에 전도성 시멘트 복합재료를 함침시키는 두가지 방법을 활용하였다. 실험 결과 염소 침투에 의해 전기전도도가 일부 증가하는 경우와 함께 반대로 감소하는 경우도 동시에 발견되었다. 본 논문은 본 연구진의 기존 논문 Lee et al.(2019)을 요약한 것이다.