Refers to the chemical method of planting reinforcement with glue in building engineering, referred to as planting reinforcement. It is a connection technology of post-anchorage of steel bars in seismic reinforcement engineering of building structures, and it is the best choice for structural reinforcement and heavy-load fastening. Chemical reinforcement planting refers to drilling holes in concrete, surrounding rock and other substrates, and then injecting high-strength reinforcement glue (note: high-strength building reinforcement glue can be roughly divided into injection reinforcement glue and barrel reinforcement glue). It is a common construction engineering technology in the steel bar industry to insert steel bars or profiles and bond the steel bars with the base material after the glue is cured.
Relevant codes and regulations of reinforcement planting technology
The scheme preparation, rebar planting construction, inspection and acceptance of this project are based on Technical Specification for Reinforcement of Concrete Structures (CECS 25: 90). In fact, this standard does not have very specific provisions on steel bar planting technology. This ancient code has been replaced by Code for Design of Reinforcement of Concrete Structures (GB50367-2006). The standard closely related to the acceptance of bar planting should be Technical Specification for Post-anchorage of Concrete Structures (JJ145-2004), and there are local standards in different regions, such as Chongqing local standard "Code for Construction and Acceptance of Inorganic Anchorage Materials for Concrete" DBJ/T50-032-2004 (hereinafter referred to as "Code")
Terminology in Article 2.10.5 of JJ145-2004: chemical planting of rebar-a kind of post-anchored rooting rebar that uses chemical adhesive (anchoring adhesive) to bond and fix ribbed rebar and long screw in the anchoring hole of concrete matrix; Terminology in article 2. 1. 10 of GB50367-2006: rebar planting-use special structural adhesive to anchor ribbed rebar or fully threaded screw in foundation concrete. These two terms about what is "rebar planting" define the type of rebar used for rebar planting: ribbed rebar or fully threaded screw. The transverse rib of ribbed steel bar can make the implanted steel bar colloid form a rib that engages with the transverse rib of the steel bar in the anchorage section. These ribs are mechanical splines to ensure the long-term anchoring performance of implanted steel bars. The spline is too shallow to form effective engagement with the transverse rib of steel bar, and the spline is too deep to resist the shear caused by engagement with the transverse rib of steel bar. Clause 12. 1.4 of GB50367-2006 stipulates that the relative rib area of ribbed steel bars shall meet the following requirements. The shape of cold-rolled and twisted steel bars can not only form mechanical teeth, but also make the local colloid too thick, which will lead to great shrinkage and affect the anchoring effect. Moreover, the colloid thickness of the anchorage section varies greatly. The thicker the colloid, the greater the shear deformation and the smaller the shear stress, while the thinner the colloid, the greater the shear stress, which leads to the uneven bonding shear stress between reinforcement and colloid and affects the effect of rebar planting. Therefore, the cold-rolled and twisted steel bars should not be used in the roof panel design of this project for planting steel bars!
Cold-rolled and twisted steel bars cannot be used for planting steel bars. Can round steel bars be used? In a project, the author once saw an example of vertical distribution of steel bars in a shear wall anchored by Grade I steel bars with a diameter of 8 mm.. Whether the first-grade steel can be used for "rebar planting" is controversial in the industry at present. JGJ 145-2004 and GB50367-2006 stipulate that round steel is not used, because round steel can't form mechanical tooth key, and the long-term anchorage performance of rebar planting can't be guaranteed.
Article 3.0. 1 of DBJ/T50-032-2004 stipulates that the concrete bar planting technology is not applicable to all kinds of lightweight concrete structures, masonry structures and load-bearing structures equipped with round steel. Non-load-bearing structure pull into the structure of the bar planting construction can refer to this procedure. According to this regulation, it is very important to distinguish structural members. In the design of Rachel reinforcement of infilled wall of frame structure, planting reinforcement should be allowed, but the vertical distribution reinforcement of grade I reinforced shear wall should not be used as planting reinforcement for anchorage. It should be noted that the local standard Southwest 05G70 1 series of drawings recommended three methods of Rachel reinforcement for infilled walls. The first method is to reserve Rachel bars, the second method is to embed iron pieces, and the last method is to plant bars. However, in the national standard 06G614 promulgated later, two methods, namely reserved lacing and embedded iron parts, were restricted, and rebar planting did not advocate infilled wall lacing.