1 Scope
This standard specifies the limit and determination of water-soluble chromium (VI) content for general purpose portland cement.
This standard is applicable to general purpose portland cement and other cements for which the adoption of this standard is specified.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 12573 Sampling method for cement
GB/T 17671 Method of testing cements - Determination of strength (ISO method)
JC/T 681 Mixer for mixing mortars
JJG 196 Verification regulation of working glass container
3 Index requirements
The water-soluble chromium (VI) content for cement shall not be greater than 10.00 mg/kg.
4 Tests
4.1 Cement specimen preparation
Samples shall be taken according to the method specified in GB/T 12573, and the samples sent to the laboratory shall be representative and uniform. The specimen shall be split to about 1,000 g as specimen to be tested, and put into a sealed, clean and dry container, and mixed well. All operations shall be carried out as quickly as possible to reduce the exposure time of specimen in the air.
4.2 Test methods
As specified in Annex A.
5 Inspection rules
5.1 Inspection types
5.1.1 The index requirements specified herein are applicable to type inspection items.
5.1.2 Under normal production conditions, cement production enterprises shall conduct water-soluble chromium (VI) content inspection at least once every six months.
5.1.3 Inspection shall be carried out under any of the following conditions:
——trial production and stereotyping of new product;
——upon off-site production of the product;
——when change takes place in production process, refractory material and raw material;
——where the production is resumed after halt for more than six months.
Foreword i
1 Scope
2 Normative references
3 Index requirements
4 Tests
5 Inspection rules
Annex A (Normative) Determination of the water-soluble chromium (VI) content for cement - Diphenylcarbazide spectrophotometric method
