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Embedded optical fiber Bragg grating (FBG) sensors are used to evaluate the properties of high performance concrete (HPC), subjected to high thermal strain. HPC is composed of polypropylene fibers and steel fibers, as additives, in a cylindrical concrete filled steel tube (CFT). A good agreement response between the FBG temperature sensor and a thermocouple was obtained. In addition, experimental results indicate that a CFT behaves differently from unconfined concrete in the center of a specimen, at a furnace temperature of 250 • C and that polypropylene fibers potentially have a higher capability to restrain spalling than do steel fibers.

The valorization of industrial solid wastes in civil engineering is one of the main routes for enhancing resource cycle toward environmental and social sustainability. In this study, an integrated approach to capturing CO2 in flue gas and stabilizing solid wastes for utilization as supplementary cementitious material via a high-gravity carbonation (HiGCarb) process was proposed. The fly ash (FA) generated from a circular fluidized bed boiler in the petrochemical industry was used. The effect of different operating parameters on the carbonation conversion was evaluated by the response surface methodology. The maximal carbonation conversion of FA was 77.2% at a rotation speed of 743 rpm and an L/S ratio of 18.9 at 57.3 °C. In addition, the workability, strength development, and durability of the blended cement with different substitution ratios (i.e., 10%, 15%, and 20%) of carbonated FA were evaluated. The results indicated that cement with carbonated FA exhibited superior properties, e.g., initial compressive strength (3400 psi at 7 d in 10% substitution ratio) and durability (autoclave expansion <0.15%) compared to cement with fresh FA. After HiGCarb, the physico-chemical properties of FA were upgraded, e.g., lower heavy-metal leaching and stabilized volume expansion, which were beneficial to usage as green materials in construction engineering.

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