In some projects, the horizontal joints of prefabricated sandwich exterior wall are not installed with sealant and PE rod after temporary fixation, but directly blocked with slurry.
In some projects, the control of reinforcement protective layer of prefabricated stair flight slab is poor, and the sampling inspection qualification rate of reinforcement protective layer of escalator components does not meet the specification requirements.
6.
The construction quality of exterior wall waterproof joints at the construction site of waterproof and blocking joints still needs to be improved.
02 pay attention to the implementation of the main responsibilities of all parties and highlight the primary quality responsibility management of the construction unit.
In some projects, only horizontal members such as laminated plates are accepted, and wall plate load-bearing members are not accepted.
The construction unit shall strengthen the quality control of reinforcement grouting sleeve connection and waterproof joints of external wall joints, and improve the process control and quality verification of key processes.
5、 Next step 01 the project participating units shall further implement several provisions on Further Strengthening the quality management of assembled integral concrete structure projects in Shanghai, guidelines for the quality management of waterproof technology of assembled integral concrete buildings in Shanghai, and notice on Further Strengthening the construction quality management of reinforced sleeve grouting connection of assembled integral concrete structure projects in Shanghai And other document requirements.
03 the supervision organization shall further strengthen the supervision of fabricated concrete structure works, and order relevant units to rectify and seriously investigate and deal with those who fail to implement their quality responsibilities and have potential quality hazards on site due to violations..
3.
There is a long interval between the grouting implementation of prefabricated wallboard and the actual hoisting construction in some projects.
1、 Inspection overview in this inspection, a total of 30 fabricated concrete structure projects under construction were randomly selected in the whole city, including 20 shear wall structure projects and 10 frame and frame shear structure projects, with a prefabrication rate of 20% ~ 40%.
In many projects, the temporary support has been removed without grouting at the connection of wallboard or the grouting strength does not meet the design requirements.
The construction unit shall strengthen the quality control of all links of assembly type construction engineering.
Improper design of exterior wall waterproof joints of some projects causes hidden dangers of structural safety and leakage.
In some projects, the system of holding certificates for grouting and hoisting operators is not well implemented.
The inspection of the project quality management system found that the construction unit did not effectively manage the quality of the fabricated structure project on site.
There are quality defects in the grouting plumpness of reinforcement sleeve in some projects, random construction of node reinforcement due to unclear requirements for in-depth design, local strength of cast-in-situ concrete of the structure is lower than the design requirements, non-standard use and construction of sealing materials, improper selection of components and frequent quality problems, and there are potential structural safety hazards in some projects.
3、 Main problems (I) construction quality 1.
7.
The grouting plumpness of the reinforcement sleeve of vertical load-bearing components in some projects does not meet the requirements, and the slurry in the sleeve is not full, which affects the mechanical performance of the joint.
The main stressed reinforcement of the structure is not set according to the design requirements during the installation of reinforcement works on site.
The preparation of special construction scheme for grouting and waterproof of some projects lags behind, and the implementation of the scheme is not enough.
The selection of stair run slab of escalator in some projects does not meet the design requirements.
The construction of prefabricated shear wall reinforcement sleeve connection in structural member connection part is not standardized, resulting in structural safety hazards in member connection.
The connection form of prefabricated components of prefabricated concrete structure is mainly reinforced sleeve grouting connection.
The opening of individual wallboard components causes the exposure of reinforcement, and the opening in the detailed drawing enhances the lack of expression.
The longitudinal reinforcement of edge members of post cast structure of some works is missing; The bottom reinforcement of the superimposed floor slab is not arranged in full length; Lack of main beam stirrup at the junction of primary and secondary beams; Due to the occupation of reinforcement in beam column joints and beam wall joints, the bending anchor reinforcement on the upper layer of beam and the longitudinal reinforcement extending into the joint of frame column are arbitrarily cut during construction and installation, resulting in insufficient anchorage length of reinforcement, etc.
Although the conclusion of the strength test report of standard curing is qualified, the concrete strength of the corresponding cast-in-situ shear wallboard and frame column is lower than the design requirements through non-destructive testing.
Further strengthen the concrete quality management, improve the concrete pouring, vibration and maintenance, and standardize the witness sampling behavior to ensure the concrete quality.
2.
For the projects with quality problems in the finished prefabricated components, the component manufacturer shall be notified and handed over to the housing and Urban Rural Development Commission for relevant credit punishment.
During the on-site inspection, 30 quality problem rectification notices and 8 local construction suspension orders were issued, and violations were reported to 6 projects and 15 related units.
The design value of reinforcement protective layer is 20mm, and the thickness of reinforcement protective layer of installed stair run slab is 15mm.
The construction drawing lacks the expression of relevant contents of prefabrication and assembly, there are no requirements for plane split layout of typical components in the design drawing, and the requirements of node details in the construction drawing do not meet the requirements of design depth.
At the same time, we should pay attention to the constraints on the quality performance of professional units.
Some projects do not pay attention to the material management of sealing joints.
5.
Source: in order to implement the spirit of Several Provisions on Further Strengthening the quality management of assembled integral concrete structure projects in Shanghai (hjza [2017] No.
（2） Quality problems caused by design 1.
The requirements for the configuration of torsional reinforcement of precast beam, the extension of reinforcement of precast frame beam joint into the support, and the section change of reinforcement of precast frame column at the bottom and top elevation of the structure are not clearly expressed in the detailed design drawing.
The first section installation and acceptance procedure of concrete members is not standardized.
2.
2、 Overall inspection and evaluation this inspection shows that the awareness of quality responsibility and management level of all parties involved in the construction of prefabricated structures in the city have been improved through the promotion of regulatory policies for prefabricated structures.
The witness sampling of concrete strength test specimens of some projects is a mere formality.
For projects with quality problems in grouting plumpness, on the basis of administrative disposal of the general contractor and the supervision unit, the professional units implementing grouting shall be subject to administrative punishment according to law, and the grouting operators shall be handed over to the Municipal Construction Association for industrial punishment.
The inspection includes on-site construction quality, on-site component quality, sampling inspection of raw materials and structural entity inspection.
Supervision side station is a mere formality, and some typical quality problems are not pointed out.
241), guidelines for quality management of waterproof technology of assembled integral concrete buildings in Shanghai (hjza [2020] No.
The joint waterproof joint between precast wallboard and precast bay window is not clear, etc.
4.
20), and other documents, To further improve the construction quality of fabricated building structure engineering, Shanghai Construction Engineering Safety and quality supervision station will carry out special inspection on the construction quality of fabricated building structure engineering in the whole city from July to August 2021.
There are weak links in the on-site quality management of some engineering components.
3.
Concrete quality management on site concrete quality management still needs to be strengthened.
The responsible units involved in serious violations of relevant laws, regulations and technical specifications in the inspection shall be given administrative penalties, and the relevant responsible persons shall be scored.
However, the inspection also found that the quality awareness of some units was weak, and the current quality verification methods for the key links of the fabricated structure were imperfect, resulting in weak quality control, and the quality problems of all links of the participating enterprises further appeared on the construction site.
During the inspection of prefabricated component installation, it is found that the construction level of reinforcement sleeve grouting still needs to be improved.
The component detailed design drawings of some projects have not been reviewed and confirmed by the original main structure design unit, and the implementation of the original structure design intention is unclear.
See the annex for details.
The bottom section of prefabricated columns of frame structure is filled with sealing materials, and its compressive strength and deformation performance indexes are not tested as required.
4、 Results disposal: the project and responsible unit that have been inspected for violations of laws and regulations shall be notified of the city and ordered to make comprehensive rectification.
