Abstract
A parabolic stress–strain constitutive model for inorganic thermal-insulating material confined by carbon fiber-reinforced polymer (CFRP) exposed to a surrounding elevated temperature was proposed in this paper. The thermal-insulating material used in this study was composed of high-early-strength cement (HESC) and perlite powder. The compression strengths of four kinds of perlite powder composition ratios of thermal-insulating materials cylindrical specimens which were confined by one, two, and three-layer CFRP composite materials were acquired. The experimental results showed that the compression strength was enhanced as the amount of perlite substitute decreased or as the number of CFRP wrapping layers increased. The Mohr–Columb failure criteria were adopted to predict the maximum compressive strength of CFRP-confined inorganic thermal-insulating material. The strain at the maximum compressive strength was found from the experimental results, and the corresponding axial strain at the maximum compressive strength in the constitutive model was determined from the regression analysis. Furthermore, the compressive strengths of the four different perlite composites of thermal-insulating materials were obtained when heating the specimens from ambient temperature to 300 °C. The compressive strength decreased with an increase in temperature, and a thermal softening parameter model was proposed; the thermal softening parameter was determined from the experimental maximum compressive strength at an elevated temperature. Combining the above two models, the constitutive model of HESC with perlite powder additive as a thermal-insulating material confined by CFRP under elevated temperature was proposed.
Highlights
Petrochemicals are critical to the development of the global industry, and low-carbon steel-made pipelines are commonly used for transporting petroleum products because they are the most cost-effective
This study aims to build a performed on specimens made of high-early-strength cement (HESC) with various proportions of perlite at different temperatures
The experimental procedures comprised compressive strength tests of thermal-insulating materials made of HESC with various ratios of perlite powder which were confined by carbon fiber-reinforced polymer (CFRP) composite materials
Summary
Petrochemicals are critical to the development of the global industry, and low-carbon steel-made pipelines are commonly used for transporting petroleum products because they are the most cost-effective. In aspects of the thermal conductivity and mechanical properties of results indicated that the compressive strength of the concrete specimen diminished while the lightweight concrete, the compressive strength and elastic modulus decreased with the increment of replacement rate of perlite powder increased. Instead of cylindrical reinforced concrete columns, the compression strength of square strength increased with the number of CFRP wraps, and the strains of CFRP-confined concrete specimens columns can be improved by enclosing with CFRP composite materials as well. Rousakis et al used transversely strength increased with the number of CFRP wraps, and the strains of CFRP-confined concrete placed basalt composite rope as an external confining reinforcement and combined this with FRP specimens decreased with the higher inherent strength of the concrete [28]. The test results showed that the bond strength of the CFRP-overlaid specimens has a significant degradation at a temperature of 200 ◦ C. da Costa Mattos et al [34] analyzed the glass fiber-reinforced polyurethane repair system for corroded metallic pipelines; it was shown that the water temperature (between 60 and 90 ◦ C) was a major shortcoming in the use of polymeric material in the repair system
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