Conductive cementitious materials have gained immense attention in recent years owing to the possibility of achieving multifunctional materials. The usual approach has been to incorporate carbonaceous nanomaterials and/or virgin carbon fibres into cementitious matrices. This paper presents the first research devoted to the development of conductive cementitious materials using recycled carbon fibres (rCFs). Four different types of PANbased rCFs were studied, by varying the aspect ratio and supplying characteristics, in two concrete dosages: conventional and ultra-high-performance concrete mixes. Two mixing methods-dry and wet-commonly used to fabricate fibre-reinforced concrete were considered. The results obtained in our result have shown that wet mix method achieves better

This paper studies the microstructural and tribological differences of layers formed during the ferritic nitrocarburizing of AISI 4340 alloy steel and AISI 347 stabilized stainless steel. The samples were exposed to different times of immersion in a nitrocarburizing bath (60, 75, 90, 105 and 120 min) at 580 °C. Subsequently, they were subjected to an oxidation process at 480 °C in order to form a Fe3O4 layer. Surface microstructural studies were carried out by SEM-EDS and x-ray diffraction (XRD). Wear and friction coefficient of nitrocarburized samples and non-treated samples were studied by pin-on-disk test. The results show two well-differentiated zones in AISI 4340 steel: an outer oxides layer, a white layer or compound layer and a diffusion zone. However, the compound layer was not found in AISI 347 steel. In both steels, the specific wear coefficient (k) of nitrocarburated samples is about thirty times lower than the reference samples.

The electrical and piezo-resistive responses of recycled carbon fibre (rCF)-reinforced concrete is analysed in this article. Two different PAN-based rCFs (monofilament rCF and fibrillated rCF sheets) incorporated into dry concrete mix were investigated. Piezo-resistivity was evaluated by simultaneously monitoring the variation in the applied DC voltage during both flexural and compressive tests. Although both plain and rCF-reinforced concrete samples showed piezo-resistive responses, the latter show increased signal-to-noise-ratio and thus behave like self-sensing materials. The electrical behaviour suggests a mixed control owing to both ionic and electronic conductivity, with the dominant one depending on the rCF content