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Self-compacting concrete (SCC) is a cementitious composite which serves complex formworks without mechanical vibrations with superior deformability and high resistance to segregation. Besides, the recycled aggregate concrete (RAC) is also developing rapidly and along with the ever-increasing sustainable demand for infrastructure. The combination of the fibers, RAC, and SCC may create advantages for the construction industry. In this study, the polypropylene (PP) fiber at 0.1, 0.15, 0.2, and 0.25% volume fractions and steel fibers at 0.25, 0.5, 0.75, and 1% volume fractions are introduced into fiber-reinforced recycled aggregate selfcompacting concrete (FR-RASCC). Both fresh property and hardened mechanical performance, comprising compressive and tensile strengths and modulus of elasticity are analyzed. The fibers validate the optimal 0.1% volume fraction for PP fiber and 0.75% volume fraction for steel fiber. In addition, the results are proved to enhance the mechanical properties and reduce cracking despite the negative impact on the fresh property. Moreover, the experimental outcomes are compared with previous researches to establish the linear model, demonstrating the relationship between fiber fraction and the mechanical properties. K E Y W O R D Sfiber-reinforced recycled aggregate self-compacting concrete, polypropylene fibers, recycled aggregate concrete, self-compacting concrete, steel fibers

It is known that accelerated carbonation technology can stabilise municipal solid waste incinerator air pollution control (APC) residues through encapsulation of hazardous components and cementation by carbonate precipitation. The aim of this work was to investigate the possibility of sequestering flue gas CO 2 in APC residues with a view to reducing greenhouse gas emissions. The fundamental parameters affecting the carbonation process have been studied. An adverse effect of the CO 2 concentration was observed and the optimum water-to-solid ratio and temperature were 0.3 and 20-30 C, respectively. The reaction consisted of two stages. Initially, the reaction rate was controlled by the movement of the carbonation interface and the activation energy at this stage was 14.84 kJ mol À1 ; as the reaction proceeds, the rate controlling regime switched to gas diffusion through product layer control, and the activation energy was calculated to be 30.17 kJ mol À1 . The openness of the pores in the solid is the key to carbonation efficiency. 10-12% (w/w) of CO 2 can be trapped in APC residues during the carbonation process if flue gas is used.

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