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Raw material control measures of concrete mixing station

Author: admin Release time: June 14, 2017 Number of visits:

1、 Cement

1. Portland cement conforming to the current national standard Portland cement, ordinary portland cement (gb175-1999) shall be used. If it is necessary to adjust the varieties, the application must be submitted 45 days in advance, and the corresponding trial matching should be done.

2. In addition to the inspection on the variety, grade, packing or bulk warehouse number and delivery date of cement entering the site, the soundness, setting time and strength of each inspection batch with the same type, strength grade and factory number not exceeding 500t must be retested;.

3. Strengthen the performance monitoring of cement entering the site, such as the detection of incoming temperature.

4. Strictly prevent mixing strength of the same grade and cement grade. After the cement is stored for more than three months, the physical properties shall be tested again, and the cement shall be used according to the re inspection results, and the cement shall not be used in important parts of the structure.

2、 Aggregate

1. Strengthen the control of aggregate performance, origin, manufacturer and test report to ensure the stability of aggregate performance and source.

2. According to the current technical standard for coarse aggregate (jg53), the standard of coarse aggregate for concrete (jg53) is adopted. The fine aggregate shall be water washed sand conforming to the technical index requirements of the current industry standard "quality standard and inspection method for sand for ordinary concrete" (jg52).

3. Strictly control the mud content and clay block content in coarse and fine aggregate, use medium and coarse sand, and ensure continuous gradation of coarse and fine aggregate.

4. According to the strength grade of concrete and the engineering position, the types of coarse and fine aggregate are selected.

5. The alkali activity index of the aggregate should meet the national standard to ensure that the coarse and fine aggregates are low alkali active or non alkali active, and the radiation performance index can meet the specified requirements.

6. It is strictly forbidden to mix harmful substances that affect the performance of concrete.

3、 Admixture

Grade I fly ash conforming to the current national standard fly ash for cement and concrete (gb1596) shall be adopted as far as possible, and the mix proportion shall be designed according to the specification for mix proportion design of ordinary concrete (jgj55-2011). If the witness sampling retest is grade II, the mix proportion shall be designed according to grade II. The design can be carried out according to grade I only when the witness sampling retest is grade I, and the spot check by station personnel shall be accepted at any time.

4、 Admixtures

1. The pumping agent that meets the technical requirements of the first-class product in the current industrial standard concrete pumping agent (jc473) or the superplasticizer that meets the technical requirements of the first-class product in the current national standard concrete admixture (gb8076) and the expansion agent that meets the first-class technical requirements in the current industrial standard concrete expansion agent (JC476) are adopted. In winter construction, antifreeze that meets the technical requirements of the first grade in the current industrial standard concrete antifreeze (jc475) shall be used.

2. Before using the admixture, the adaptability test should be carried out strictly.

3. Ensure that the ammonia content in the admixture meets the relevant provisions of the current national standard "limits of ammonia release from concrete admixtures" (GB 18588).

4. The alkali content and chloride ion content in the admixture shall be strictly controlled, and the relevant requirements specified in the current national standard technical specification for application of concrete admixtures (GB 50119-2003) shall be met.

5、 Water

All mixing water is drinking water.

6、 Ensure the authenticity and validity of all kinds of raw materials.

7、 Ensure that all kinds of raw materials are classified and stored with clear identification.