GB 8076-2008Concrete Admixtures (English PDF)

3.1 High performance water reducer

It is superior to high efficiency water reducer in the following aspects. higher water- reducing rate, better slump keeping performance, less dry shrinkage and a certain performance of air entraining.

3.2 Reference cement

The cement that meets the requirements in Appendix A of this Standard and is specially used to inspected concrete admixture performance.

5.1 Performance indexes of test concrete

Performance of concrete added with admixture shall meet the requirements listed in

Table 1.

5.2 Uniformity indexes

Uniformity index shall meet requirements of Table 2.

6.1 Materials

6.1.1 Cement

Cement specified in Appendix A of this Standard is adopted.

6.1.2 Sand

Medium sand which meets the requirements of Area II in GB/T 14684; but the fineness modulus is 2.6 ~ 2.9 and silt content is less than 1 %.

6.1.4 Water

It shall meet the technical requirements for water consumption of concrete mixing specified in JGJ 63.

6.1.5 Admixtures

The admixtures that need to be inspected.

6.2 Mixing proportion

Reference concrete mixing proportion is designed according to JGJ 55.The proportion of test concrete added with non-air-entraining admixture shall be the same with that of cement, sand and crushed-stone of the corresponding reference concrete. Mixing proportion design shall meet the following provisions.

6.3 Concrete mixing

Adopt the single-lay-shaft forced blender with nominal capacity of 60L and that meets the requirements stipulated in JG 3036.The mixing amount of blender shall neither be less than 20L nor greater than 45L.

6.4 Sample preparation and sample amount needed in test

6.4.1 Sample preparation

Concrete sample is prepared and cured according to GB/T 50080; however, concrete pre-curing temperature is (20±3) °C.

6.4.2 Test items and sample amount

Test items and amount are listed in Table 3.

6.5 Performance test method of concrete mixtures

6.6 Performance test method of hardened concrete

6.6.1 Compressive strength ratio measurement

Compressive strength ratio is represented by the ratio of compressive strengths

BETWEEN concrete added with admixture AND same-duration of reference concrete.

It is calculated according to Formula (9), accurate to 1%.

6.7 Uniformity test methods

6.7.1 Chloride ion content measurement

Chloride ion content is measured according to GB/T 8077 or the method specified in

Appendix B of this Standard. For arbitration, the methods stated in Appendix B are applied.

6.7.2 Measurement of solid content, total alkali amount, water content, density, fineness, pH value and sodium sulfate content

It shall be measured according to GB/T 8077.

7.1 Sampling and lot number

7.1.1 Spot-sample and mixing-sample

Spot-sample refers to a sample obtained from the product in one-time production.

Mixing-sample refers to the sample that is obtained after three or more spot-samples are mixed equivalently and evenly.

7.1.2 Lot number

Manufacturer shall number the products by lot according to output and manufacturing equipment condition. Each lot number of admixture, with the same type and whose mixing proportion is greater than 1% (including 1%), is 100t; and each lot number of admixture, whose mixing proportion is less than 1%, is 50t.

7.2 Samples and reserved-sample

Samples taken from each lot shall be thoroughly and evenly mixed, which shall be divided into two equal-portions. In which, one portion is tested according to the items listed in Table 1 and Table 2, and the other is sealed and conserved for half a year.

authorities for retest or arbitration.

7.3 Inspection classification

7.3.1 Exit-factory inspection

Items of exit-factory inspection of each lot of admixtures are inspected according to the items specified in Table 4 and based on different varieties.

7.3.2 Type inspection

Type inspection items include all performance indexes in Chapter 5.Under any of the following conditions, type inspection shall be carried out.

7.5 Retest

Retest shall be carried out with sealed and reserved samples. If user-organization requires for on-site sampling, then the requirements shall be specified in procurement contract in advance, and mixing-sample shall be taken on-site when both personnel from the manufacturer and user-organization are present.

8.1 Product instructions

When products leave the factory, product instructions shall be provided; it shall include the following content at least.

8.2 Packages

Powder admixture may be packed with woven bag lined with plastic bag; liquid admixture may be packed with plastic bucket or metal bucket. Error of net mass package shall be not greater than 1%. Liquid admixture may also be packed in tank- truck in bulk.

8.3 Product exit-factory

In case of any of the following conditions, the products shall not leave the factory.

incomplete technical documents (product instructions, certificate and inspection report etc.), non-conformant package, insufficient mass, deteriorated product by moisture, and expired products. Controlling value of product uniformity index shall be indicated in related technical material clearly.

8.4 Storage

Admixture shall be stored in special warehouse or in fixed place for well-keeping; take the principle of easy to identify, convenient to check and delivery. During handling period, products shall be taken and placed gently to prevent damage. In addition, damping shall be avoided during transportation.

8.5 Return of products

Under specified storage condition and in valid period, if user-organization discovers that admixture performance is inconsistent with those specified in this Standard after retest, it shall be allowed to return or replace.

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