ASTM C563

ASTM C563 – Standard Guide for Approximation of Optimum SO3 in Hydraulic Cement

Description:

Significance and Use

3.1 The purpose of this guide is to estimate the SO₃ content for a hydraulic cement that gives maximum performance. The value obtained is one way to establish an appropriate level of sulfate in the manufacture of cements specified in Specifications C150/C150M, C595/C595M, and C1157/C1157M.

3.2 The SO₃ content of a cement giving maximum performance is different at different ages, with different performance criteria and with different materials such supplementary cementitious materials and chemical admixtures. A manufacturer can choose the performance criteriato determine optimum SO₃ content. This optimum SO₃ content may be a compromise between different ages and different performance criteria.

NOTE 1: Typically, the optimum SO₃ content is higher the later the age.

3.3 This guide indicates optimum SO₃ content for cement, optionally in presence of supplementary cementitious materials and admixtures. Several alternate methods are allowed: compressive strength of concrete or mortar, heat of hydration of paste or mortar, and drying shrinkage of mortar.

3.4 It should not be assumed that the optimum SO₃ estimated in this guide is the same SO₃ content for optimum performance of a concrete prepared in the field using the same materials. The optimum SO₃ is influenced by parameters such as ambient and fresh concrete temperature, admixtures, and supplementary cementitious materials.

3.5 The guide is applicable to cements specified in Specifications C150/C150M, C595/C595M, and C1157/C1157M.

Scope

1.1 This guide describes the determination of approximate optimum SO₃ for maximum performance as a result of substituting calcium sulfate for a portion of the cement.

1.2 This guide refers to the sulfur trioxide (SO₃) content of the cement only. Slag cements and occasionally other hydraulic cements can contain sulfide or other forms of sulfur. The determination of SO₃ content by rapid methods may include these other forms, and may therefore produce a significant error. If a significant error occurs, analyze the cement for SO₃ content using the reference test method of Test Methods C114 for sulfur trioxide.

1.3 Values stated as SI units are to be regarded as standard.