Green and Environmental Protection Recycled Concrete in Road Engineering

In response to a series of national strategic guidelines for green and sustainable development, recycled concrete is used as a recyclable resource. First, the mechanical properties, workability, and durability of recycled concrete are briefly introduced, and the benefit and necessities of research on recycled concrete are described from environmental, economic, and social perspectives. Second, the mixing method and molding process of recycled concrete are described in detail, and the influence of vibration molding and compression molding on the performance of recycled concrete is analyzed. It is found that the compressive strength first increases and then decreases with the increase of molding pressure. In addition, porosity decreases as molding pressure build-up. Therefore, it is recommended that the molding pressure of recycled concrete be generally controlled between 600 and 800 N. Then, the influence of the water-cement ratio on recycled concrete’s fluidity and mechanical properties is discussed. It is found that with the increase of the water-cement ratio, the compressive strength first increases and then decreases and the optimum water-cement ratio is proposed to be 0.2. Finally, the application status and problems of recycled concrete in road engineering are briefly described, and relevant suggestions for construction technology are put forward. Based on the fire safety and reliability requirements of concrete structures, the performance of high-performance concrete structures after fire can be restored to the initial level or even improved through the processes and measures of building structure design, repair, and reinforcement; the strength and crack healing of high-performance concrete after fire can be gradually restored by applying or soaking repair agent and water curing; the recovery of pH value of concrete after fire and the reduction of carbonation depth can be realized by using electrochemical realkalization technology; using carbon fiber to strengthen the components after fire can restore the bearing capacity, but the degree of stiffness recovery is low; and beam side steel plate reinforcement and steel bonding reinforcement can realize the recoverability of bearing capacity, stiffness, and ductility of members after fire.