ASTM C1622

ASTM C1622 – Standard Specification for Cold-Weather Admixture Systems

Description:

Abstract

This specification covers cold-weather admixture systems to be added to hydraulic-cement concrete when the temperature of the concrete immediately after placement will be low. This specification stipulates tests of the cold-weather admixture system with suitable materials specified or with materials proposed for specific work, and provides three levels of testing. The apparatus used shall be suitable for low temperature environment. The concrete, cementitious materials, aggregates, and air-entraining admixture shall be tested and shall conform to the values of chemical and performance requirements such as initial setting time, compressive strength, shrinkage, durability.

Scope

1.1 This specification covers cold-weather admixture systems to be added to hydraulic-cement concrete when the temperature of the concrete immediately after placement will be as low as -5.0 °C [23.0 °F] prior to the time of initial set.

1.2 This specification stipulates tests of the cold-weather admixture system with suitable materials as described in 11.1 – 11.3 or with materials proposed for specific work (See 11.5). Unless otherwise requested by the purchaser, tests shall be made using suitable concreting materials as described in 11.1 – 11.3.

NOTE 1: Whenever practicable, tests should be made using the concreting materials, the mixture proportions, and batching sequence proposed for the specific work (See 11.5) because the time of setting, compressive strength gain, and other properties may vary.

1.3 This specification provides three levels of testing.

1.3.1 Level 1—During the initial approval stage, proof of compliance with the performance requirements defined in Table 1 demonstrates that the cold-weather admixture system meets the requirements of this specification. Uniformity and equivalence tests (See Section 6) shall be carried out to provide results against which later comparisons can be made.

(A)The values in the table include allowance for normal variation in test results

(B)As an example, in the case of initial time of setting, if the control mixture has a set time of 4.0 hrs, the test specimens can have a set time up to 8.0 hrs. For length change, if the control specimen shrinks X units, the test specimen is allowed to shrink up to 1.35X.

(C)The compressive strength of the concrete containing the cold-weather admixture shall not be less than 90 % of that attained at the previous test age. The objective of this limit is to require that the compressive strength of the cold-weather admixture concrete shall not decrease with age.

(D)Because the test specimens will be cool and damp for the 7d compressive test, it will be necessary to use unbonded caps as described in Practice C1231/C1231M.

(E)Alternative requirements, see 17.1.2: Percent of control applies when shrinkage of control concrete is 0.030 % or greater; the increase over control limit applies when shrinkage of control concrete is 0.030 % or less.

(F)This requirement is applicable only when the cold-weather admixture is to be used in air-entrained concrete that may be exposed to freezing and thawing while wet.

1.3.2 Level 2—Limited retesting is described in 5.2, 5.2.1, and 5.2.2. Proof of compliance with the requirements of Table 1 demonstrates conformity of the admixture system with the requirements of this specification.

1.3.3 Level 3—For acceptance of a lot or for measuring uniformity within or between lots, when specified by the purchaser, uniformity and equivalence tests (See Section 6) shall be used.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the inch-pound units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 The text of this standard references notes and footnotes, which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.