How to plant rebar well?

Building engineering in the construction process is divided into nine parts:

Positioning → drilling → hole cleaning → reinforcement treatment → preparation of anchoring glue → reinforcement planting → curing, protection → inspection.

Our workers drill holes at the required anchorage depth, and the aperture ensures that the gap between steel bars on each side is greater than 2mm. Then the workers clean the holes with an air pump, and the holes are clean and free of dust. The amount of rebar planting glue should ensure that the hole is full, and the rebar should be screwed in to make the orifice overflow slightly. After the reinforcement glue is consolidated, the workers should carry out on-site pull-out test. The next step can only be carried out after passing the test.

First, positioning

First, we mark the drilling position and model according to the design requirements. If there are reinforced bars on the base material, the drilling position can be adjusted appropriately, but they should all be planted inside the distribution bars of the shear wall. Dig anti-slip holes, and punch small holes with chisels at the marked points of rebar planting, so as to avoid sliding dislocation of the drill bit when drilling.

Second, drilling

The drilling type is percussion drilling. First of all, the drilling is generally vertical to the plane of concrete members, with a slope of no more than 8 degrees (except for being too close to the floor and having no operating space or special requirements), and the drilling depth is 15d(d is the diameter of reinforcement). When drilling, the progress should not be too fast, so as not to affect the concrete strength around the drilling due to the heating of the drill bit. When drilling, if the main reinforcement or stirrup in the original structure needs to be displaced and avoided, it must be approved before it can be displaced.

Third, hole cleaning

When cleaning the dust in the hole, if the dust accumulates in the hole during drilling, especially when drilling downward, the dust is not easy to run out, so it should be cleaned frequently, otherwise it will burn out the drilling rig and the drill bit. At this time, workers should use a hair dryer for high-pressure washing when cleaning holes. After drilling is completed, the dust in the hole is blown out with compressed air after the hole depth and aperture are qualified, then the hole wall is brushed with a brush, and the compressed air is blown out again, which should be repeated for 3-5 times until there is no dust and debris in the hole, and before the glue is poured, the hole wall is free of dust, oil pollution and organic impurities.

Four, steel processing

According to the design requirements of the drawings, the length of steel bars should be determined before blanking. If external steel bars are welded, the steel bars should be welded first and then planted. If it is difficult, they must be welded later. The distance between the welding spots and the concrete surface of the base material should be greater than 15d(d is the diameter of steel bars), and the roots of the exposed parts of the steel bars should be wrapped with a wet towel soaked in ice water, that is, the minimum length of the steel bars to be welded later is: hole depth+welding length +15d, so as to avoid high temperature affecting the strength of the glue during welding. Steel bar surface treatment: use electric steel wire or manual steel wire brush to remove rust on the steel bar surface, and use acetone or alcohol to remove oil stain and dust on the steel bar surface.


V. Preparation of anchoring glue

There are two kinds of rebar-planting glues, namely, barreled rebar-planting glues, which are composed of component A and component B. Mechanical stirring is suitable for the glue distribution. The stirrer can be composed of electric hammer and stirring teeth, and the stirring teeth can be made of cross φ 14 steel bars welded at the end of electric hammer bit. A small amount can be stirred manually with a thin steel bar. Take a clean container (plastic or metal basin, free of oil, water and impurities) and mix it with a weighing scale according to the mixture ratio, and stir it with a stirrer for about 10 minutes until the components A and B are evenly mixed. It is best to stir in the same direction when stirring, and try to avoid mixing air to form bubbles. Glue should be used now, and the amount of glue should not be greater than 5 kg each time.

Six, implanted steel bar

After the bar planting glue is prepared according to the design requirements, it is manually fed with glue, which is 2/3 of the hole depth. Implant the processed steel bars into the holes filled with structural adhesive; Manual insertion method: Insert the steel bar into the hole, because the structural adhesive has a certain concentration, it can't be inserted to the bottom at one time. Pull out, insert or rotate repeatedly until the steel bar is inserted into the fundus (note that sometimes it will rebound after being inserted to the bottom, which should be prevented). Center positioning of steel bar: Because the diameter of the drilled hole is larger than that of the implanted steel bar, the implanted steel bar may not be in the center, so stones are used to support and position the hole, and then the hole is closed with hard glue to play a fixing role to prevent the glue in the hole from flowing out of the hole.

VII. Curing and Protection

Curing time refers to the hardening time of structural adhesive, but the strength of the adhesive only reaches 40%-60% of the design strength. When the temperature is 20℃, it will take about 48 hours to reach the design strength, so structural adhesive is generally required to anchor the steel bar. After the construction is completed, it will take 48 hours according to the environmental temperature before the stress is allowed. Before the structural adhesive is solidified, the anchor bars should be protected, and the anchor bars should not be swayed and collided, and special personnel should be assigned to protect them on site.

Eight, quality inspection

Measure the length of exposed steel bars in drilling holes to determine the depth of implanted steel bars. Measure whether the position, model and diameter specifications of rebar planting are wrong (make records). Carry out drawing test, and the supervision engineer will identify and approve the test results. The allowable deviation of rebar planting depth is +20mm, and the allowable deviation of verticality is 5.

Nine, it is forbidden to deal with quality problems overnight, and make a quality summary every day.