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Frost Resistance of Thermoinsulating Recycled-Aggregate Concretes Containing Glazed Hollow Beads
Zhaoxu Wang,Yuanzhen Liu,Yaodong Guo,Yu Zhao,Lucen Hao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.2
Glazed hollow bead (GHB) is an innovative material that gives concrete very good thermal-insulation properties and improves concrete frost resistance, when used as a partial replacement of ordinary fine aggregate. The improvement in frost resistance under freeze-thaw cycles and the deterioration mechanisms of recycled aggregate thermoinsulating concretes (RATICs) is the objective of this study, after adding GHBs to the mix. Fifteen cubes and ninety prisms made of five RATIC mixes (GHB content = 0, 40, 65, 90 and 130 kg/m3) were tested in compression, to identify the optimum content of GHB. The degradation mechanisms of RATIC were identified based on mass loss, dynamic elastic modulus and uniaxial compressive strength. In addition, RATIC mesostructure was investigated by means of Computed Tomography Scanning, and the deterioration mechanisms by analyzing pore amount, average and maximum pore area and porosity. The experimental results demonstrate that adding glazed hollow beads to recycled aggregate concrete (RAC) moderately changes the mesostructure of the concrete, to the advantage of frost resistance, and that the optimum content of GHB is around 90 kg/m3.
Surface Mesh Generation in Parametric Space Using a Riemannian Surface Definition
Cui Dai,Zhaoxue Wang,Liang Dong,Yiping Chen,Junfeng Qiu 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2
In order to solve the problem of generating distortion elements in the mapping from parameter space to real space, and the boundary coincidence of the mesh generated by the software quality, an approach for parametric surface mesh generation based on Riemannian metric, combined with Delaunay triangulation and AFT is proposed. In our algorithm, the boundary curves are discretized based on the proximity and curvature of the curves in the model after derivation the correlation of curve length between parametric space and real space. Background meshes of parametric space were generated by using improved AFT, and could improve the efficient of the algorithm and control element sizing and metric values. When background mesh of parametric space were refined, to counteract mapping distortion, the traditional Delaunay incremental insertion kernel is replaced by inserting the center of triangle circumscribed ellipse, and the algorithm for locating ellipse center and judging whether nodes within ellipse. In this paper, the details of the surface mesh generated by the algorithm are introduced in detail. The algorithm proposed in this paper has the characteristics of reliable algorithm, high mesh generation efficiency and mesh quality. Finally, the reliability of the proposed algorithm is verified by an example of surface mesh generation.