1.1 This specification covers materials for use as chemical admixtures to be added to hydraulic-cement concrete mixtures in the field for the purpose or purposes indicated for the seven types as follows:
1.1.1 Type A8212;Water-reducing admixtures,
1.1.2 Type B8212;Retarding admixtures,
1.1.3 Type C8212;Accelerating admixtures,
1.1.4 Type D8212;Water-reducing and retarding admixtures,
1.1.5 Type E8212;Water-reducing and accelerating admixtures,
1.1.6 Type F8212;Water-reducing, high range admixtures, and
1.1.7 Type G8212;Water-reducing, high range, and retarding admixtures.
1.2 This specification stipulates tests of an admixture with suitable concreting materials as described in 11.1-11.3 or with cement, pozzolan, aggregates, and an air-entraining admixture proposed for specific work (11.4). Unless specified otherwise by the purchaser, the tests shall be made using concreting materials as described in 11.1-11.3.
Note 18212;It is recommended that, whenever practicable, tests be made using the cement, pozzolan, aggregates, air-entraining admixture, and the mixture proportions, batching sequence, and other physical conditions proposed for the specific work (11.4) because the specific effects produced by chemical admixtures may vary with the properties and proportions of the other ingredients of the concrete. For instance, Types F and G admixtures may exhibit much higher water reduction in concrete mixtures having higher cement factors than that listed in 12.1.1.
Mixtures having a high range water reduction generally display a higher rate of slump loss. When high-range admixtures are used to impart increased workability (6 to 8-in. slump [150 to 200–mm]), the effect may be of limited duration, reverting to the original slump in 30 to 60 min depending on factors normally affecting rate of slump loss. The use of chemical admixtures to produce high-slump (flowing) concrete is covered by Specification C 1017
Note 28212;The purchaser should ensure that the admixture supplied for use in the work is equivalent in composition to the admixture subjected to test under this specification (see Section 6, Uniformity and Equivalence).
Note 38212;Admixtures that contain relatively large amounts of chloride may accelerate corrosion of prestressing steel. Compliance with the requirements of this specification does not constitute assurance of acceptability of the admixture for use in prestressed concrete.
1.3 This specification provides for three levels of testing.
1.3.1 Level 18212;During the initial approval stage, proof of compliance with the performance requirements defined in Table 1 demonstrates that the admixture meets the requirements of this specification. Admixtures (except for Types B, C, and E) shall qualify for provisional compliance when the physical requirements and any of the alternative compressive strength requirements in Table 1 are met. If subsequent test results at 6 months or one year fail to meet the standard requirement of 100 % of reference strength, the compliance of the admixture to this standard is withdrawn and all use......
Copyright ©2024 All Rights Reserved