Evaluation of the Durability of Hydrophobic Treatments on Concrete Architectural Heritage
Abstract The protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration. Existing commercial products - mainly silane or siloxane in either water or solvent based formulations - were submitted to different ageing processes including UV radiation, dry-wet cycles, thermal shocks, freeze-thaw cycles, carbonation and their effectiveness has been evaluated on the basis of contact angle, vapour and chloride permeability and, capillarity water absorption. The results obtained clearly show that hydrophobic treatments display a good behaviour under the main ageing conditions.
Churches and Concrete in Liège District: History, Architecture and Pathologies
Reinforced concrete is a key element of the architectural evolution and has been specifically involved in the development of religious architecture. Since its discovery in the nineteenth century, this invented material, economic and fire resistant, however showed its limits: cracks, spalling and disintegration are some of the degradations we may observe today. It therefore seems necessary to worry about the current state of churches: these monuments are indeed the testimony of architectural evolution but also landmarks for the neighborhood. In Liège district, Belgium, nine parish churches have been identified as mainly concrete based. For each church, a visual inspection has been realized: this overview led us to make an assessment of the monument, with regard to concrete and reinforced concrete situation. This inspection is the first step for further investigations included into a restoration or renovation process.
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.