We all know that the chloride ions contained in natural sea sand can cause the corrosion of steel bars in traditional concrete, and then lead to concrete cracking, so the preparation standards of sea sand concrete are very strict.
On November 15, the General Office of the Ministry of Housing and Urban-Rural Construction issued a notice for public consultation on the industry standard "Technical Specification for the Application of Sea Sand Concrete (Draft for Partial Revision)".
This partial revision involves the amendment of six articles. Article 3.0.1, Article 3.0.4, Article 4.1.2, Article 4.2.2, Article 5.1.3 and Article 5.2.
Partial Revision of Exposure Draft (Revised Part)
III. Basic provision
3.0.3.0.
Change to:
3.0.3.0.3.0.4 Delete
IV. Raw materials
4.1 Sea
sand 4.1.2 The quality of sea sand shall conform to Table 4.1. The test method for quality inspection of sea sand shall conform to the provisions of the current industry standard Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete JGJ 52.
Change:
4.1.2 The quality of sea sand shall conform to Table 4.1. The test method for water soluble chloride ion content of sea sand shall adopt the rapid test method in Appendix A and Appendix B of this specification. In case of any dispute, it shall/should/can be judged according to the current national standard GB/T 14684 of Sand for Construction. Other test methods for sea sand quality inspection shall conform to the relevant provisions of the current national standard GB/T 14684 of Sand for Construction. 4.2
. Fly ash and granulated blast furnace slag powder shall respectively comply with the provisions of the current national standards Fly Ash for Cement and Concrete GB/T 1596 and Granulated Blast Furnace Slag Powder for Cement and Concrete GB/T 18046. 4.2
. Fly ash shall comply with the relevant provisions of the current national standard Fly Ash for Cement and Concrete (GB/T 1596), and granulated blast furnace slag powder shall comply with the provisions of the current national standard Granulated Blast Furnace Slag Powder for Cement and Concrete (GB/T 18046). Steel slag powder shall comply with the provisions of the current national standard Steel Slag Powder for Cement and Concrete GB/T 20491, and granulated electric furnace phosphorus slag powder shall comply with the provisions of the current industrial standard Granulated Electric Furnace Phosphorus Slag Powder for Cement and Concrete JG/T 317. Natural pozzolanic materials shall comply with the provisions of the current industry standard Natural Pozzolanic Materials for Cement Mortar and Concrete JG/T 351, and limestone powder shall comply with the provisions of the current national standard Limestone Powder Concrete GB/T 30190. The composite admixture shall comply with the provisions of the current industrial standard Composite Admixtures for Concrete (JG/T 486). The use of other admixtures shall be subject to systematic test research and demonstration, and shall be verified by long-term performance and durability tests.
Five、 Performance
of sea sand concrete 5.1 Technical requirements
for mixture 5.1.3 The maximum content of water-soluble chloride ion in sea sand concrete mixture shall conform to Table 5.1. The content of water-soluble chloride ion in sea sand concrete mixture shall be determined according to the rapid determination method of chloride ion content in concrete mixture in the current industry standard Test Code for Concrete in Port and Waterway Engineering JTJ 270. 5.1.3 The maximum content of water-soluble chloride ion in sea sand concrete mixture
used for structural engineering shall comply with Table 5.1. The content of water-soluble chloride ion in sea sand concrete mixture shall comply with the current industry standard Technical Specification for Detection of Chloride Ion Content in Concrete (JGJ/T). Method for determination of chloride ion content in concrete mixtures in 322. When calculating the maximum content of water-soluble chloride ions, the amount of auxiliary cementitious materials shall not be greater than amount of Portland cement, and inactive cementitious materials shall not be included in the cementitious materials. 5.2
Mechanical properties
5.2. The mechanical properties of sea sand concrete shall be tested and determined in accordance with the provisions of the current national standard Standard for Test Methods of Mechanical Properties of Ordinary Concrete GB/T 50081, and shall meet the design requirements. 5.2
. The mechanical properties of sea sand concrete shall be tested and measured in accordance with the provisions of the current national standard Standard for Test Methods of Physical and Mechanical Properties of Concrete GB/T 50081, and shall meet the design requirements.
Appendix A: Rapid Test Method for Water-Soluble Chloride Ion in Sea Sand — Chloride Ion Selective Electrode Method:
A.0.1 Instruments and equipment shall meet the following requirements:
1. Chloride ion selective electrode: the measurement range is 5 × 10-5 ~ 5 × 10-2 mol/L, the pH range is 2 ~ 12, the response time is not more than 2 min, and the temperature range is 5 ℃ ~ 45 ℃;
2. Reference electrode: double salt bridge saturated calomel electrode. The potential-chloride ion concentration curve shall be established according to the following steps before the salt bridge is charged with 0.1mol/L KNO3 or
0.A.0.2:
1. The chloride ion-selective electrode shall be placed in 0.A.0.3 prepared
from distilled or deionized water. The test shall be carried out as follows:
1. Before the test, the chloride ion selective electrode shall be placed in
0.A.0.4, and the calculation and determination of the chloride ion content of sea sand shall meet the following requirements:
1. The water-soluble chloride ion content of sea sand shall be calculated according to the formula (A.0.4) and shall be accurate to 0.01%;
2. The content of water-soluble chloride ions in sea sand shall be the arithmetic mean of the results of two tests. And shall be accurate to 0.
Appendix B: Rapid Test Method for Water-Soluble Chloride Ions in Sea Sand — Test Tube Method:
B.0.1 Instruments and equipment shall comply with the following provisions:
1. The rapid test tube for chloride ions shall be verified by the standard sample of sea sand. Chloride ion content test with measuring range of 0.002 ~
0.B.0.2 shall be carried out according to the following steps:
1. 500g of sea sand shall be put into a clean ground bottle, and 500g of distilled water shall be added;
2. A magnetic stirring device shall be used to continuously stir for 15 minutes;
3. Cut off the two ends of the chloride ion rapid test tube, see Fig. B.1 for the schematic diagram;
Fig. B.1 for the schematic diagram
of the cutting position of the test tube 4. Insert the filter at the end A, and install the suction ear ball at the end B of the test tube, see Fig. B.2 for the schematic diagram;
Fig. B.2 Schematic Diagram
of Installation of Filter and Suction Ball 5. Insert 1/3 ~ 1/2 of the lower end of the filter into the ground bottle, and use the suction ball to suck the filtrate into the test tube. See Fig. B.3 for the schematic diagram;
Fig. B.3 Schematic diagram of
inserting the filter into the ground bottle 6. The detection agent in the test tube is brown. When the chloride ion reacts with the detection agent, it will turn white. When the moisture indicator shows blue, it indicates that the reaction is complete. The suction ear ball should be removed immediately after the reaction is complete;
7. Observe the chromogenic part of the test tube, and immediately read the highest and lowest readings of the chromogenic part (Figure B.4). The water-soluble chloride ion content of sea sand shall be the average value of the highest and lowest readings. And shall be accurate to 0.
Figure B.4 Schematic diagram
of data reading 8. After reading, the syringe shall be immediately installed to the end A of the chloride ion rapid test tube through the connecting rubber tube. See B.5 for the schematic diagram;
Fig. B.5 Schematic Diagram
of Syringe Installation 9. Pull out the syringe push rod, and buckle the fixing wire on the upper end of the syringe plastic tube to prevent the push rod from moving. Hold for 20 to 30 seconds to suck out the excess filtrate in the chloride ion rapid test tube. See B.6 for the schematic diagram;
Figure B. B.
0.3 The arithmetic mean of the two test results shall be taken as the determined value, to the nearest 0.
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