On December 10, Jinhua Housing and Urban-Rural Construction Bureau issued the Notice on Publishing the Results of Spot Inspection of Production Quality of Ready-mixed Concrete Enterprises in 2024. Since the end of October, spot checks have been carried out on the implementation of the system and production quality of ready-mixed concrete enterprises in the whole city. Random spot checks and differential management methods have been adopted. A total of 29 ready-mixed concrete enterprises have been sampled. The results of this spot check have been formed by combining the third-party test results and the verification and inspection of the extension site. In the spot check, 26 rectification and supervision notices, 2 law enforcement proposals and 8 typical cases were issued.
The details are as follows:
of this random spot check and differential management, a total of 29 ready-mixed concrete enterprises, combined with the third-party test results and the extension of the site to verify the inspection, the results of this spot check. In the spot check, 26 rectification and supervision notices, 2 law enforcement proposals and 8 typical cases were issued.
2. Existing problems
(1) In terms
of quality control of production enterprises, a small number of enterprises have committed serious illegal acts of lending qualifications and signed business transfer contracts with unlicensed mixing sites in society; The implementation of environmental temperature and humidity control measures in the laboratories of some enterprises is not in place, and environmental control facilities such as humidifiers and dehumidifiers are not equipped as required; the number of individual instruments and equipment (balances) is not uniform, resulting in non-standard measurement range, and the calibration status identification of some equipment is out of date, affecting the accuracy of detection and measurement; The re-inspection of raw materials is not standardized, the re-inspection batches do not meet the standard requirements, and the original re-inspection records are incomplete. Some enterprises lag behind in the statistical evaluation of the strength of impermeable concrete and low-grade concrete below C30.
(2) Sampling inspection of raw materials and strength rebound test
of on-site solid components 1. A total of 76 samples of machine-made sand and fly ash raw materials were sampled in this inspection, and the comprehensive qualified rate of various quality indicators was 83.1%, among which the unqualified phenomenon of fly ash activity indicators was more common; 2. A total of 58 components were sampled for the strength rebound test of solid components on site, and the qualified rate was 87. The rebound strength of most unqualified components had reached more than 95% of the design strength, and the rebound strength of individual project solid components was seriously low.
(3) Implementation of
relevant documents on concrete quality improvement 1. Some concrete production enterprises have not strictly controlled the content of fly ash and mineral powder in various strength mix proportions according to the requirements of document No.12 of Jinshi Construction [2024]. The proportion of fly ash and mineral powder in cementitious materials in one or more strength mix proportions does not conform to the requirements of the documents, and the design mix proportions of some enterprises are not calculated and adjusted according to the strength standard deviation of 6.0; 2.
III. Typical case
(I) Main problems of Jinhua Jiaotou Construction Industrialization Co., Ltd.
: After contracting business, the unqualified unit "Jinhua Baihui Engineering Technology Co., Ltd." Signed a concrete supply contract with the general contracting enterprise of the project construction, and provided the product certificate. Some of the products were produced through other illegal sites, and the tax sales invoices were issued by Baihui Company, which was suspected of transferring or lending the qualification certificate or transferring the contracting business; the information of the origin and brand of raw materials such as mineral powder was inconsistent with the quarterly public information; the sampling results of raw materials such as fly ash were not qualified; the random sampling of C50 production mix ratio was inconsistent with the actual production value.
(II) Main problems of Zhejiang Lanfeng New Building Materials Co., Ltd.
: After extended inspection of the physical quality of the supply project Wucheng Wansheng Huafu Phase II Project, the rebound strength of the site components is seriously inconsistent with the design strength (the design value is C30, and the estimated value of the rebound of the column wall on the 12th floor of 26/J-H axis is 20.0 MPa. Estimated value of roof structure beam rebound of 25/B-D axis (20.5MPa); Batch inspection was carried out for the unqualified components, and the estimated value of rebound was converted according to the carbonization depth value of 2.5mm.
(III) The main problems of Jinhua Longding Concrete Co., Ltd.
were as follows: the strength rebound test of on-site solid components was unqualified; the sampling results of fly ash raw materials were unqualified; The place of origin, brand and other information of raw materials such as mineral powder are inconsistent with the quarterly public information; there is no record of concrete mix proportion adjustment and trial mix after the implementation date (August 15) of JSJJ [2024] No.12 document.
(IV) Main problems of Yiwu Guhe Commercial Concrete Co., Ltd.
: the mix proportion of C30 and C35 in the spot check in October showed that the content of mineral powder was not less than 20% of the total amount of cementitious materials; the spot check result of fly ash raw materials was unqualified; The mix proportion design was not adjusted according to the requirements of JSJJ [2024] No.12 Document, and the standard deviation of configuration strength was not adjusted according to 6.
(V) Main problems of Dongyang Shizhan Transportation Industry Development Co., Ltd.
The content of fly ash is not less than 15% of the total amount of cementitious materials, and the content of mineral powder is not less than 20%. The sand and gravel silo for concrete production is mixed with the open-air sand and gravel sales site, which is seriously inconsistent with the closed management regulations of the sand and gravel silo for concrete production.
(VI) Main problems of Jinhua Boxiang Garden Construction Co., Ltd. (Ivy Community Project)
: signing a concrete purchase contract with a mixing station without concrete production and operation qualification; failing to organize concrete delivery inspection as required.
(VII) Main problems of Zhejiang Construction Engineering Group Co., Ltd. (Complex Building Project of Wucheng Sub-branch of Jinhua Chengtai Rural Commercial Bank)
: Zhejiang Lanfeng New Building Materials Co., Ltd. The concrete delivery inspection records of the complex building project of Jinhua Chengtai Rural Commercial Bank Wucheng Branch constructed by Zhejiang Construction Engineering Group Co., Ltd. on August 21 and August 31 showed that the slump value was too large; the floor slab was measured and set out within 24 hours after pouring, and the auxiliary materials were lifted. All of the above do not meet the relevant requirements of Jinshi Jianjian [2024] No.12 Document.
(VIII) Main problems of Zhejiang Baixia Construction Co., Ltd. (Old Village Reconstruction High-rise Residential Project of Yi'an Village, Houzhai Street)
: Spot check the seven-storey floor panel of Building 2 of the project supplied by Yiwu High-tech Zone Building Materials Technology Co., Ltd. and constructed by Zhejiang Baixia Construction Co., Ltd. There are membrane lifting operations such as measuring and setting out, lifting auxiliary materials within 24 hours after pouring; there is no monthly summary of concrete delivery inspection, and there is a phenomenon that the slump value of concrete at the pouring part of components below 27 meters is greater than 180 mm. All of the above do not meet the relevant requirements of Jinshi Jianjian [2024] No.12 Document.
4. Handling opinions
: Jinhua Trading and Construction Industrialization Co., Ltd., which has been listed as a typical case for two consecutive quarters, shall be included in the list of enterprise products to be used cautiously in the next quarter, and shall be placed on file for investigation; Zhejiang Lanfeng New Building Materials Co., Ltd., Jinhua Longding Concrete Co., Ltd., Yiwu Guhe Commodity Concrete Co., Ltd. and Dongyang Shizhan Transportation Industry Development Co., Ltd., which violate the provisions of JSJJ [2024] No.12 Document for the first time, are included in the list of key regulatory enterprises in the next quarter; the Ivy Community Project is given a "red card" warning; A "yellow card" warning was given to the comprehensive building project of Wucheng Branch of Jinhua Chengtai Agricultural and Commercial Bank and the high-rise residential project of Yiwu Houzhai Street.
For the relevant concrete enterprises with unqualified quality indicators in the sampling inspection of raw materials, it is required to carry out batch inspection and verification of the concrete solid components produced and supplied by the same batch of raw materials, and to implement the closed-loop rectification according to the results of the inspection and verification; For the relevant concrete enterprises and construction units with unqualified components in the spot check of the rebound strength of concrete solid components, it is required to carry out batch inspection and verification of the same strength grade concrete components poured in the same batch by the third party inspection agency, and implement the closed-loop rectification according to the verification results; the Wansheng Huafu Phase II Project in Wucheng District shall report the rectification plan to the local competent construction department; The competent construction department of Wucheng District shall intensify the spot check of all projects under construction supplied by Zhejiang Lanfeng New Building Materials Co., Ltd. to Wucheng District in November, and carry out the strength test of concrete solid components according to the proportion of spot check of all real estate projects and no less than 50% of other projects.
5. Requirements
for the next step (1) Strengthen the quality control of production process. All ready-mixed concrete enterprises should strengthen the construction of quality system of raw materials and products, make full use of information tools, strictly manage the use and testing of raw materials, and ensure the batch and frequency of testing. Standardize the quality control of ready-mixed concrete production process, improve the management measures of ready-mixed concrete factory inspection, ensure that the data stored in the system can be accessed at any time, and ensure the accuracy and traceability of the test data.
(2) Strengthen environmental management in production areas. All ready-mixed concrete enterprises should strictly implement the environmental control measures in the concrete production area, and consciously do a good job in road hardening and dust control in the plant area.Vehicle travel routes ensure that there is no residue leakage, no tire mud and other phenomena, so as to achieve green production and civilized driving.
(3) Implementing the quality responsibility of the main participants. All construction, supervision and construction units should further implement the quality control of the whole process of ready-mixed concrete construction, strictly implement the on-site delivery inspection procedures in accordance with the requirements of relevant documents for quality improvement in 2024, strengthen the relevant provisions for pouring and maintenance, resolutely put an end to the act of adding water during pouring, and resolutely put an end to the act of making false test blocks.
(4) Effectively strengthen industry supervision. The competent construction departments of counties (cities and districts) should strengthen the supervision of ready-mixed concrete production enterprises and all parties involved in construction projects, strictly supervise and spot check the links of delivery and delivery, strengthen the quality control of the source of concrete raw materials, and ensure the quality of ready-mixed concrete; At the same time, we should continue to follow up and supervise the construction of key processes such as concrete pouring, formwork removal and maintenance, so as to ensure the quality of concrete components under construction.
(5) Give full play to the guiding and self-discipline role of associations. Concrete industry associations should further guide the healthy competition of ready-mixed concrete enterprises, guide enterprises to standardize internal testing and improve the level of information management in accordance with the "Jinhua City Ready-mixed Concrete Enterprise Standardization Laboratory On-site Evaluation Standards (2023 Edition)", assist the competent authorities in quality and safety control, and urge member units to implement green. To promote the sustainable and healthy development of ready-mixed concrete production industry in our city.
