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Introduction:Full-recycled-aggregate concrete (aRAC) is a new concrete reusing 100% fine and coarse recycled aggregates produced from waste concrete of demolished concrete structures. As there is a lack of studies on the bond behavior between steel bar and aRAC, findings of this study are of significance for the structural application of aRAC. Method:This paper presents the pull-out test results of 24 groups aRAC specimens with deformed steel bar, and discusses the effects of aRAC strength, bond length and lateral constructional stirrups on the bond behavior between deformed steel bar and aRAC. Results and Conclusion:The bond stress and slip at key points of bond-slip curve are analyzed in relation to the tensile strength of aRAC and the bond length of steel bar. The bond-slip relationship between deformed steel bar and aRAC is proposed based on the test and analysis of this study.

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Amine compounds can greatly enhance the thermal stability of the insulating paper used in paper-oil insulation. Many research documents focus on paper's excellent thermal stability, but less attention has been paid to the effect of oil on paper's degradation. In this research paper, we study the influence of different amine compounds on the thermal stability of both paper and oil, and a mechanism for the influence on paper-oil insulation as well as an optimal formula are proposed. First, six groups of paper were modified with different proportions of dicyandiamide (DICY), melamine, and polyacrylamide (PAM). Then, an accelerated thermal aging test at 130 • C was conducted for 30 days and the thermal aging characteristics of the oil-modified paper insulation were measured. The results showed that the thermal stability of the insulation paper modified with the amine compounds was remarkably improved, and P2 (2.25 wt % melamine, 0.75 wt % DICY, and 0.2 wt % PAM) presented the best anti-aging properties. However, certain properties of oil were influenced, such as acid value, and it was found that the ammonia produced by the amine stabilizers increased the copper compound content, which led to the deterioration of the insulating oil. Moreover, using a front-line orbital energy analysis by molecule modeling, it was determined that melamine was the core thermal stabilizer for the paper among the three amine compounds used in P2.

A greatly enhanced breakdown electric field of ∼8 kV/cm was achieved in multi-doping ZnO ceramics, and the role of defects in determining the electrical properties were systematically investigated in this work. At low temperature of around 203 K, it is found that the dielectric loss is composed of dc conduction and two defect relaxation peaks with activation energy at 0.24 eV and 0.37 eV, which can be effectively described according to Debye relaxation theory. At high temperature of 473 K, anther two defect relaxation peaks with activation energy at 0.65 eV and 0.98 eV are found to obey Cole-Davidson function, which are greatly affected by additives and closely related to the electrical properties of ZnO ceramics. Additionally, impedance analysis shows that the grain boundary resistance of ZnO ceramics is increased from 0.56 MΩ to 15.7 MΩ at 473 K and the corresponding activation energy of grain boundary is elevated from 0.23 eV to 1.03 eV. The frequency dependence of the conductivity is interpreted with the Jonscher's law, which indicates that the contribution of dc conduction at low frequency can be evidently suppressed by additives. An equivalent circuit model is demonstrated for expounding the association between enhanced electrical properties and defect relaxation in ZnO ceramics.

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Activate electrolyte enhanced supercapacitors (AEESCs) are considered as promising tools for power capacity due to their high specific capacitance and simple creation form. However, there are many challenges, such as...