It became clear when I first entered the site to re-test the concrete admixtures.

Items for on-site re-inspection of concrete admixtures: should be determined according to relevant standards. Usually, the on-site re-inspection items for different admixtures are not exactly the same. Generally common re-inspection items are:

(1)PH value, density (or fineness), water reduction rate, etc.

(2) Early-strength superplasticizer increases the corrosion of steel bars and the ratio of 1d and 3d compressive strength;

(3) Retarding water reducing agent increases the setting time difference;

(4) Air-entraining agent increases the air content;

(5) Early strength agent increases the 1d and 3d compressive strength ratio;

(6) Pumping agent increases slump Increased drop value and slump loss value;

(7) The addition of expansion agent limits the expansion rate; the accelerating setting agent increases 1d compressive strength and setting time.

Batch grouping and sampling

1) According to "Concrete Admixtures" (GB8076-1997 ) Standard concrete admixtures: each inspection batch of the same type of admixture with a content of ≥1% is 100t, and each inspection batch of admixtures with a content of ≤1% is 50t. If the quantity is less than 100t or 50t, it can also be regarded as one inspection batch.

2) Waterproofing agent: Every 50t of waterproofing agent with an annual output of more than 500t is an inspection batch; every 30t of waterproofing agent with an annual output of less than 500t is an inspection batch. If the quantity is less than 50t or 30t, it will also be regarded as one inspection batch.

3) Pumping agent: Every 50t of waterproofing agent with an annual output of more than 500t is an inspection batch; every 30t of waterproofing agent with an annual output of less than 500t is an inspection batch . If the quantity is less than 50t or 30t, it will also be regarded as one inspection batch.

4) Antifreeze: Every 50t of antifreeze is an inspection batch, and any amount less than 50t is also an inspection batch.

5) Accelerator: Every 20t of antifreeze is an inspection batch, and less than 20t is also an inspection batch.

6) Expanding agent: When the daily output exceeds 200t, 200t shall be regarded as one inspection batch. When the daily output is less than 200t, the daily output shall not exceed one inspection batch.

7) Sampling quantity for each inspection batch: the maximum amount of antifreeze should be no less than 0.15t of cement; the amount of quick-setting agent should be no less than 4kg; other admixtures shall not be less than the amount of admixture required for 0.2t of cement.

The samples obtained from each inspection batch should be fully mixed and divided into two equal parts. One copy shall be tested according to the specified items; the other shall be sealed and kept for half a year in case of doubt, and submitted to the nationally designated testing agency for re-inspection or arbitration.

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