Reinforced recycled lump/aggregate concrete precast column and construction method thereof
A reinforced recycled block/aggregate concrete precast column and a construction method are provided. The reinforced recycled block/aggregate concrete precast column includes several first one-bar hoops, vertical reinforcement bars, several second one-bar hoops, a flexible hinge area, and recycled block/aggregate concrete; the first one-bar hoops and second one-bar hoops are each provided with an anchor end; the first one-bar hoops and second one-bar hoops are disposed in the flexible hinge area, and only the second one-bar hoops are disposed outside the flexible hinge area; the outer edge of each first one-bar hoop is flush with the outer surface of the reinforced recycled block/aggregate concrete precast column; and the interior of the reinforced recycled block/aggregate concrete precast column is filled with the recycled block/aggregate concrete, thereby greatly increasing the recycling rate of engineering waste, reducing shedding of a concrete protective layer in the flexible hinge area of the column.
1. A reinforced recycled lump/aggregate concrete precast column, comprising a plurality of first one-bar confinements, longitudinal bars, a plurality of second one-bar confinements, a plastic hinge region, and recycled lump/aggregate concrete;
each of the first one-bar confinements and each of the second one-bar confinements being provided with an anchoring end;
the plurality of first one-bar confinements and some of the plurality of second one-bar confinements being arranged in the plastic hinge region, and some of the second one-bar confinements being arranged outside the plastic hinge region; outer edges of the first one-bar confinements being flush with outer surfaces of the reinforced recycled lump/aggregate concrete precast column, the first one-bar confinements being configured to restrain a concrete cover, and a vertical spacing between two adjacent first one-bar confinements of the first one-bar confinements being not greater than 200 mm; the second one-bar confinements abutting against the longitudinal bars, and the second one-bar confinements being configured to restrain the longitudinal bars;
the anchoring end being formed by bending at 135° twice; and
an interior of the reinforced recycled lump/aggregate concrete precast column being filled with the recycled lump/aggregate concrete, the recycled lump/aggregate concrete consisting of fresh concrete and demolished concrete lumps, and the fresh concrete being recycled aggregate concrete containing recycled coarse aggregates and excavated soil, wherein
a mass ratio of the recycled coarse aggregates to natural coarse aggregates in the fresh concrete is not greater than 4, the excavated soil partially or completely replaces natural sand, and a mass ratio of the excavated soil to the natural sand is not less than 1
a strength grade of the fresh concrete is not lower than C40; and
the demolished concrete lumps are lumps formed by breaking old buildings, structures, and roads after removing all or part of steel bars, and a characteristic size of each of the demolished concrete lumps is not less than 60 mm.
2. The reinforced recycled lump/aggregate concrete precast column according to claim 1 , wherein a mass ratio of the demolished concrete lumps to the fresh concrete in the recycled lump/aggregate concrete is 1:4 to 2:3.
3. The reinforced recycled lump/aggregate concrete precast column according to claim 2 , wherein each of the first one-bar confinements and each of the second one-bar confinements is a stirrup formed by bending a high-strength steel bar for multiple times, and a size of the outer edge of each of the first one-bar confinements is larger than the size of an outer edge of each of the second one-bar confinements.
4. The reinforced recycled lump/aggregate concrete precast column according to claim 3 , wherein a length of each of two straight segments of the anchoring end is not less than a larger value in 10 d and 75 mm, and d is a diameter of the stirrup.
5. The reinforced recycled lump/aggregate concrete precast column according to claim 4 , wherein a height of the plastic hinge region is between 1.0 h and 2.0 h, and h is a cross-sectional height of the reinforced recycled lump/aggregate concrete precast column.
6. The reinforced recycled lump/aggregate concrete precast column according to claim 5 , wherein a spacing between the two adjacent second one-bar confinements in the plastic hinge region is not greater than a smaller value in 6 D and 100 mm, and D is a minimum diameter of the longitudinal bars; and a spacing between the two adjacent second one-bar confinements outside the plastic hinge region is not greater than 10 D.
7. The reinforced recycled lump/aggregate concrete precast column according to claim 1 , wherein a yield strength of each of the first one-bar confinements and the second one-bar confinements is not less than 500 MPa.
8. The reinforced recycled lump/aggregate concrete precast column according to claim 2 , wherein a yield strength of each of the first one-bar confinements and the second one-bar confinements is not less than 500 MPa.
9. The reinforced recycled lump/aggregate concrete precast column according to claim 3 , wherein a yield strength of each of the first one-bar confinements and the second one-bar confinements is not less than 500 MPa.
10. The reinforced recycled lump/aggregate concrete precast column according to claim 4 , wherein a yield strength of each of the first one-bar confinements and the second one-bar confinements is not less than 500 MPa.