Abstract: A method for fully utilizing old mortar on surfaces of recycled coarse aggregates is provided. The method includes the following steps: S1, performing a weakening treatment on recycled coarse aggregates to obtain pre-treated recycled coarse aggregates, where an elastic modulus of old mortar on surfaces of the pre-treated recycled coarse aggregates is 15% to 80% of an elastic modulus of old mortar on surfaces of original recycled coarse aggregates; S2, reacting an isocyanate component and an amino compound in solvent oil to obtain a polyurea coating material, then spraying the polyurea coating material onto surfaces of the pre-treated recycled coarse aggregates to obtain modified recycled coarse aggregates; and S3, preparing recycled concrete using the modified recycled coarse aggregates obtained in the step S2.

Abstract: A process for improving crack resistance of recycled aggregate concrete is provided. The process includes following steps: (1) soaking recycled fine aggregate in an organosilicon compound for modification, thereby obtaining modified fine aggregate; (2) soaking recycled coarse aggregate in a silica sol solution, then adding quicklime, thereby obtaining modified recycled coarse aggregate; and (3) mixing cement, carbide slag, fly ash and an additive with water until uniform, then sequentially adding the modified fine aggregate and the modified recycled coarse aggregate and mixing uniformly, finally performing later-stage curing to obtain the recycled aggregate concrete.

Abstract: Disclosed are a method and equipment for reinforcing a concrete-filled steel tubular column with an outer concrete-filled steel tube. The method includes following steps: step 1, grinding and derusting an outer wall of a concrete-filled steel tubular column to be reinforced by an auxiliary device; step 2, welding two prefabricated semi-rectangular steel plates in advance, forming a complete rectangular steel tube with the two semi-rectangular steel plates and sleeving the rectangular steel tube outside the concrete-filled steel tubular column to be reinforced; and step 3, filling self-compacting concrete between the outer wall of the concrete-filled steel tubular column to be reinforced and an inner wall of the rectangular steel tube to complete a reinforcement.