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Autor(a/res): Chen An, Menglan Duan, Romildo D. Toledo Filho e Segen F. Estefen.
Resumo: Sandwich pipes (SP) with steel tubes and a lightweight flexible core are under consideration as a potential solution for ultra-deepwater submarine pipelines, combining high structural resistance with thermal insulation. Besides polymeric materials, strain hardening cementitious composites (SHCC) reinforced with polyvinyl alcohol (PVA) fibers, a micromechanically designed material with high tensile ductility, can be an option for the annular material. The purpose of this work was to investigate experimentally and numerically the collapse behavior of SP filled with SHCC under external hydrostatic pressure. The preparation procedure for SHCC and the fabrication process for SP were presented in detail. The full-scale laboratorial tests of SP were performed using a hyperbaric chamber to analyze the collapse pressure subjected to external pressure. The mechanical behavior of SHCC was simulated using a concrete damaged plasticity (CDP) model provided by the commercial finite element package ABAQUS, whose parameters were estimated by tension and compression tests. In addition, a systematic parametric study was performed to analyze the effects of ovality, thickness and outer/inner radius ratio on the collapse pressure of SP with SHCC core.
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Autor((a/res): Alex Neves Junior, Romildo Dias Toledo Filho, Eduardo de Moraes Rego Fairbairn e Jo Dweck.
Resumo: In a previous work, the authors have carbonated totally high initial strength and sulfate-resistant Portland cement pastes. In order to solve the mechanical problems caused by the intense carbonation that occurred during those experiments, new carbonation conditions were applied in this study. The obtained products were analyzed with respect to the carbonation reactions by thermogravimetry and compressive mechanical strength. Comparative analysis with reference pastes obtained without carbonation at the same age shows that CO2 capture increases with carbonation time. However, there is an optimum time, up to which the carbonation treatment does not affect the mechanical properties of the paste. Below this time, the lower is the carbonation time the higher is the increase of compressive strength, when compared to that of the reference pastes processed at same operating conditions without carbonation.
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