JJF [2015] No. 24

To the Committees of Housing and Urban-Rural Development of all districts, Committees of Housing and Urban-Rural Development of Dongcheng and Xicheng Districts, the Construction Bureau of the Economic and Technological Development Zone, all building, construction and supervision units, all ready-mixed concrete production enterprises, and all other relevant units:

In order to further standardize the quality control activities for the ready-mixed concrete used in housing projects in Beijing and ensure the structural quality and safety of housing projects, in accordance with the Construction Law, Regulations on the Administration of the Quality of Construction Projects, Beijing Municipal Construction Engineering Quality Regulations, laws and regulations, normative documents and technical standards, and in combination with the actual situation in Beijing, this Notice on further strengthening the management of ready-mixed concrete used in housing projects is as follows:

I. Strengthen the management of the procurement process of ready-mixed concrete

(I) It is forbidden for construction units to give contracts for ready-mixed concrete directly. Construction units should pay the contract price in full and on time in accordance with the general construction contract, and cannot arbitrarily compress the reasonable construction duration.

(II) The general contracting unit should fulfill the responsibility for the quality management of subcontracting units. The general contracting unit should purchase and use concrete from contracting enterprises which have the professional contracting qualification of ready-mixed concrete. Before signing the purchase contract for ready-mixed concrete, the general contracting unit should carry out an on-site inspection of the production address, production conditions, technical quality assurance capability and quality reputation of the contracting enterprises of ready-mixed concrete along with the supervision units. The general contracting unit should also report the qualification of the ready-mixed concrete contracting unit to the supervision unit in accordance with the relevant provisions.

(III) In order to ensure the quality of ready-mixed concrete products, the general contracting unit should strictly implement the provisions of Notice on Releasing the Quality Control Price of Ready-mixed Concrete (JJF [2014] No. 24).

(IV) The purchase contract for ready-mixed concrete should include the following information: production and business address (Party A and Party B), persons in charge of the project and contact information (Party A and Party B), dispatching telephone number, 7d and 28d (mass concrete 60d) index values of compressive strength of standard concrete specimens, concrete slump and other technical requirements.

II. Strengthen the management of the production process of ready-mixed concrete

(I) The concrete mix ratio used for structural parts for the first time in the unit engineering should be first determined by the general contracting unit, contracting units and supervision units of the ready-mixed concrete at the production site of the ready-mixed concrete.

(II) For housing projects which do not carry out a supervision system of the production quality of ready-mixed concrete at the plant, the general contracting unit should arrange special personnel to carry out quality inspections of the production process of the ready-mixed concrete at least three times. The inspections should focus on the actual production address, raw material quality, implementation of the production mix ratio and concrete performance of the ready-mixed concrete, as well as the filling in of the inspection records.

(III) For housing projects which don not carry out a supervision system of the production quality of ready-mixed concrete at the plant, the construction unit should carry out quality inspections of the production process of the ready-mixed concrete. The construction unit should arrange special personnel or commission a project supervision unit to inspect the production process of the ready-mixed concrete at least three times. The inspections should focus on the actual production address, raw material quality, implementation of the production mix ratio and concrete performance of the ready-mixed concrete, as well as the filling in of the inspection records.

(IV) The general contracting unit should determine the concrete slump according to the structural pouring parts, construction methods and concrete performance characteristics. The slump should meet the provisions in the Technical Specification for Concrete Mineral Admixture Application DB11/T 1029 Table 6.2.2

III. Strengthen the management of the use process of ready-mixed concrete

(I) The general contracting unit should inspect the quality of the on-site ready-mixed concrete. The general contracting unit should check each car’s relevant information in the concrete transportation list and carry out appearance quality acceptance of such performance factors as cohesiveness, water retention and so on. The concrete transport should be signed after it has been accepted as qualified. When testing the ready-mixed concrete, the general contracting unit should check the slump according to the relevant standards. The supervision unit should inspect the acceptance process of the ready-mixed concrete carried out by the general contracting unit.

(II) After the ready-mixed concrete is accepted as qualified, the general contracting unit should submit the application for the registration of ready-mixed concrete procurement in accordance with the Notice on Strengthening the Procurement of Construction Materials and Equipment for Record-keeping (BMCC Law [2011] No. 19).

(III) The general contracting unit should carry out video monitoring of the whole process from when the transport vehicles of the ready-mixed concrete enter the construction site to when the concrete mixture is discharged. The video images should be managed by a special person as construction materials, and should be saved for the final acceptance of the project.

(IV) The general contracting unit should formulate a test plan and carry out the sampling, making and marking of 7d and 28d standard concrete specimens and curing specimens of structural entities under the same conditions to inspect the structural strength of the concrete, and keep relevant video records. The video records should be able to clearly reflect the sampling sites, whole process, sample numbers, molding dates, concrete strength grades, samplers, witnesses and other information of the concrete samples. It is suggested that affordable housing projects use chips implanted in concrete specimens, two-dimensional codes or other electronic information tagging technologies.

(V) During the concrete construction process, the general contracting unit should carry out the construction in strict accordance with the Concrete Structure Construction Specifications (GB50666) and other concrete construction technical specifications. It is forbidden to add water during the conveying and pouring process of the concrete. During concrete pouring, the managers and supervisors of the general contracting unit should be present and stop adding water in good time.

(VI) In order to ensure the structural quality of the concrete, enough time should be allowed for mold maintenance. When the concrete pouring is completed, it should be moisturized and conserved in good time. The conservation time and insulation coverage measures should meet the relevant regulations. The supervision unit should inspect the curing of the concrete according to the detailed supervision rules. The supervision unit should use the rebound method or other methods stipulated by the State to carry out the parallel inspection of the strength of the structural concrete members. At least 2% of similar components should be taken for each strength grade and the number of each strength level taken should be not less than 5 pieces.

(VII) Before the quality acceptance of the concrete structures, the construction unit should entrust qualified engineering quality inspection agencies to carry out the sampling inspection of the concrete strength of the project entities. At least one member of each wall and floor should be selected. The general contracting unit should also organize the contracting units of the ready-mixed concrete and supervision units to participate in the quality acceptance of the concrete structures with the in-plant supervision system.

(VIII) The supervision unit should promptly check the project's test results in the Beijing Municipal Construction Quality Monitoring Information System and urge the general contracting unit to promptly deal with projects whose strength test results of 7d and 28d standard concrete specimens are registered as unqualified. The processing measures and results should be fully recorded in the system. For projects which are not processed in good time by the general contracting unit, the supervision unit should promptly report the construction unit and the construction administrative department.

IV.  Further strengthen the management of the ready-mixed concrete quality of all parties participating in the construction

(I) The main parties participating in the project's construction should establish an inspection system for the quality management control of the ready-mixed concrete of the corresponding project. They should also inspect such quality management behavior as procurement, on-site acceptance, pouring, vibrating, maintenance, demolding of ready-mixed concrete and construction quality.

(II) The general contracting unit should establish a list of qualified suppliers of ready-mixed concrete and concrete quality management systems to monitor the production process of the ready-mixed concrete, video monitor the production of test specimens and the whole discharge process of the concrete mixture, monitor the concrete strength-test data and carry out the warning process for any detected failures.

(III) The general contracting unit should regularly inspect the concrete quality management of the corresponding projects, focusing on the selection of ready-mixed concrete contractors, contract price, opening appraisal, concrete worker training, video data of test personnel and on-site experimental environment and facilities, whole processes of specimen production and concrete mixture discharge, and monitoring of the concrete production process, as well as the treatment of any detected specimen strength failures.

(IV) The supervision unit should inspect the qualifications of the ready-mixed concrete contracting units, review and supervise the implementation of the trial plan, monitor the concrete production process, inspect the concrete standing process, and inspect the concrete curing and treatment of unqualified results.

V. Further strengthen the supervision and management of the use of ready-mixed concrete

The municipal and district project quality supervision institutions should focus on the inspection of the fulfillment of the quality responsibility of building units, concrete units and supervision units, as well as the treatment of unqualified concrete test results. The supervision institutions should further strengthen the supervision and law enforcement of ready-mixed concrete, investigate and deal with any illegal acts that come to light, and give a score according to the relevant scoring management approach. The results should be recorded in the market behavior evaluation system.

If the units participating in the construction commit the following acts, the municipal and district administrative departments of housing and urban-rural development should urge them to make corrections. The responsible units should entrust qualified project quality inspection agencies with testing the quality of the project's structure entity. If the test results are unqualified, the relevant units should be punished severely according to the provisions of the relevant laws and regulations:

(I) The construction unit gives contracts for ready-mixed concrete directly.

(II) The general contracting unit uses ready-mixed concrete from enterprises without professional contracting qualifications.

(III) The general contracting unit is insincere about the inspection of concrete specimens.

(VI) The general contracting unit adds water during the pumping and pouring of the concrete.

VI. This Notice will take effect as of January 1st, 2016.