What are the precautions in the construction of post-cast strip?

Attention should be paid to the concrete construction of post-cast strip:

(1) The width of post-cast strip is generally 700- 1000mm, and there are three common types: 800mm, 1000mm and1200 mm.

(2) There are four joint forms of post-poured strip: straight joint, step joint, notch joint and X joint. (3) The steel bars in the post-cast strip are completely disconnected and then overlapped, and there are provisions for continuously setting additional steel bars.

(4) The concrete pouring time of post-cast strip shall not be less than 65,438+04 days, 42 days, 60 days and 28 days after capping.

(5) Concrete preparation and strength of post-cast strip, some require the original concrete to improve its strength grade, and some require that it be poured with non-shrinkage concrete of the same grade or higher.

(6) The curing time is inconsistent, including 7 days, 14 days or 28 days.

The existence of the above differences brings a lot of inconvenience to the construction and has great expansibility. Therefore, only by carefully understanding the differences of professional specifications and applying the specifications flexibly and reliably according to the characteristics and nature of the project can the quality of the project be effectively guaranteed.

Section form, reinforcement treatment and concrete pouring at the joint of post-cast strip;

(1) shall be determined according to the actual situation of wallboard thickness, with general thickness; 300mm wallboard can be made into stepped seam or trough shape symmetrical up and down; On the thickness; 600 mm walls can be made into concave or polygonal concave parts.

(2) Whether the reinforcement remains intact or disconnected depends on the type of post-cast strip. The steel bars of settlement post-cast strip should be connected, the steel bars of expansion post-cast strip should be disconnected, the plate steel bars of beam-slab structure should be disconnected, but the beam steel bars should be connected. If the reinforcement is continuously opened, the shrinkage of concrete near the reinforcement will be greatly limited, which will lead to tensile stress cracking, thus reducing the ability of the structure to resist temperature stress.

Post-poured belts in different parts should be zigzag connected.

(3) For concrete pouring of post-cast strip, generally, non-shrinkage concrete should be adopted, and expansive cement can also be mixed with ordinary cement. The strength of concrete is at least the same as or one grade higher than that of the original concrete.

Construction quality control:

The connection form of post-cast strip must be designed according to the construction drawing, the template must be inserted plate or steel mesh, and the joint interface form is provided with convex strips on the plate. Before pouring concrete, the joints should be carefully cleaned, chiseled and washed, the displaced steel bars should be reset, and the concrete must be vibrated and compacted, especially the basement floor should be carefully treated to improve its own waterproof ability.

(1) After the first pouring of post-cast strip, protective measures should be taken, including top covering and fence protection, to prevent garbage from entering the joint, steel bar pollution and trampling deformation, which will bring difficulties to cleaning.

(2) The beams and slabs on both sides of post-cast strip are in cantilever state for a long time before pouring concrete, so the formwork supports on both sides cannot be removed before pouring concrete. After pouring concrete in post-cast strip, the strength of concrete reaches above 85%, so pay attention to protection, observe and record, and maintain in time.