Method for fully utilizing old mortar on surfaces of recycled coarse aggregates

A method for fully utilizing old mortar on surfaces of recycled coarse aggregates to improve impact resistance of concrete, comprising the following steps:

• S1, performing a weakening treatment on the recycled coarse aggregates, with specific operations as follows:
• soaking the recycled coarse aggregates in a weak acid aqueous solution, and/or, placing the recycled coarse aggregates into a rotating drum with toothed rings on an inner surface for rotation, to obtain pre-treated recycled coarse aggregates;
• wherein 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 the surfaces of the pre-treated recycled coarse aggregates to form a polyurea coating on the surfaces of the pre-treated recycled coarse aggregates, thereby obtaining modified recycled coarse aggregates;
• and
• S3, preparing recycled concrete using the modified recycled coarse aggregates obtained in the step S2.