Grouting connection of steel reinforcement joints is the key to quality control that needs to be focused on in prefabricated assembly building construction. Based on relevant information and engineering practice, the inspection requirements for grouting connection of reinforcement joints in prefabricated assembled buildings are introduced as follows.

1. Connection joint inspection.

The reinforcing steel connection joint is a metal material, usually manufactured by casting or mechanical processing, generally divided into full and half grouting joints. The length of the reinforcing rebar splice should be determined according to the test, and the standard value of the yield-bearing capacity and tensile-bearing capacity of the joint at its maximum stress should not be less than 1.1 times the standard value of the yield-bearing capacity and tensile bearing capacity of the connected reinforcement.

The minimum internal diameter of the reinforcement joint's grouted section and the connected steel's nominal diameter should not be less than 10 mm (12-25 mm diameter of reinforcement) and 15 mm (28-40 mm diameter of reinforcement).

Rebar splice inspection is divided into factory inspection and type inspection. Factory inspection and material performance test should be the same steel number, specification, and furnace (batch) number of materials as an acceptance batch, randomly selected two.

Rebar splice size and appearance should be produced continuously with the same raw materials, the same type, the same specification, and the same furnace (batch), the number of 1,000 sleeves as an acceptance batch. Less than 1,000 sleeves can still be used as an acceptance batch, randomly selected 10%—material performance, size, and appearance inspection of the indicators to meet the provisions.

If the two test pieces are qualified in the material performance test, the batch of rebar splice material performance is judged to be qualified. In the joint size and appearance inspection, if the passing rate of the joint specimen is not less than 97%, the batch of joints is judged to be qualified.

Material performance, size, and appearance inspection are qualified rebar splices to be judged as qualified products before the factory use. Joints should be accompanied by a product certificate, including at least the product name, joint type, specification, strength level of the steel used, production batch number, material grade, quantity, test conclusion, inspection seal, company name, zip code, address, telephone, and fax.

2. Reinforcing rebar splice grout inspection.

Reinforcing rebar splice grout should be used with grout sleeve matching, and grout inspection is divided into factory inspection and type inspection.

Factory inspection items include:

Initial flow rate.

30 min flow rate.

1 d, 3 d, 28 d compressive strength.

3 h vertical expansion rate.

Difference between 24 h and 3 h vertical expansion rate and water secretion rate.

Type test items in addition to factory inspection of all items, in one of the following circumstances, the type test should be carried out.

(1) the final identification of new products.

(2) after formal production, such materials and processes change significantly, which may affect product quality.

(3) more than half a year out of production when resuming production.

(4) type test more than 2 years.

Manufacturers in the delivery should provide product certification, instruction manuals, and product quality inspection reports, including product quality inspection reports on the factory inspection and type inspection.

Factory inspection sampling rules are produced within 15 d of the same formula, the same batch number of raw materials to 50 t as an inspection batch, less than 50 t should also be used as an inspection batch.

The test should be taken from more than one part in equal amounts, and the total number of samples should not be less than 30 kg so that the product sampling is representative. Grout factory inspection and type inspection of the indicators meet the requirements to be judged as qualified products. Otherwise, if an indicator does not meet the requirements, it is considered an unqualified product. Grout that fails the quality inspection shall not be used in construction projects.

3. Project before use inspection.

When grouted reinforcement joints come in, grouted joints should be taken and matched with grout to make alignment joint specimens and tensile strength tests, and the test results should meet the relevant provisions before use. The number of inspections is the same batch number, the same type, the same specification of grout sleeve, not more than 1 000 for a batch, each batch of randomly selected 3 grouted rebar splices to produce alignment connection joint specimens.

The grouting connection of steel reinforcement joints in each assembly building project using prefabricated components before production should also be joint grouting joint tensile strength testing. For each project, the number of connection joint specimens of each specification is not less than three for the corresponding tensile strength test and only after passing the corresponding project.

4. Inspection in use of the project.

Before grouting construction, the grout joint grouting connection should be tested for grout mix flow, and the initial flow of grout mix should be checked not less than 1 time per work shift to ensure that the grouting operation can be carried out smoothly.

Before grouting:

Moisten the glass plate and cut off the cone mold.

Place the cut-off cone mold in the center of the glass plate.

Pour the mixed grout full of the test mold.

Vibrate and discharge the gas.

Slowly lift the cone test mold.

Please wait for the slurry to flow freely under undisturbed conditions and spread until it stops.

Measure the expansion of the two vertical directions.

Take the average value as the flow of grout.

It is required that the initial flow is not less than 300 mm, the 30 min flow is not less than 260 mm, and the general condition will be qualified between 200~300 mm.

In the process of grouting the reinforcement joints, the supervisor will supervise, and the project experimenter will make the grout compressive strength specimens. The compressive strength test shall conform to the provisions in the relevant code and shall not be less than the compressive strength of the grout required by design.

5. Other requirements.

The reinforcing steel for grouting connection of reinforcement joints should be ribbed reinforcement that meets the requirements of current standards, and the diameter of the reinforcement should not be less than 12 mm and not more than 40 mm.

Grouted rebar splices in the reinforcement strength grade and rib shape changes should also be the form of joint inspection. Reinforcing rebar splice grouting connection inspection in addition to the connection sleeve size, appearance, and grout mix flow test by the prefabricated plant, the construction unit their inspection, the rest of the test inspection should be carried out by the appropriate qualified professional institutions, an inspection of qualified inspection quality certification documents and inspection reports.

At present, reinforcing rebar splice grout is used at an ambient temperature above 5 ℃, and it is not suitable for grouting construction operations in high-temperature weather, winter, and rainy period. In addition to considering the external environment, the grouting of reinforcing rebar splices should also ensure that the specimens used for maintenance meet certain conditions of compressive strength before subsequent construction of the joints. Removing temporary fixing measures should also be carried out after the compressive strength of the grout can ensure that the structure meets the subsequent construction bearing requirements and ensure construction safety and project quality.

The above is about prefabricated assembly building reinforcement joint grouting connection inspection points. If you need more detailed information, welcome to contact us!