Canadian and U.S. Cements

Construction documents often specify a cement type based on the required performance of the concrete or the placement conditions. Research projects frequently compare the performance of varying types of cement for a given set of experiments. Certain cement manufacturing plants only produce certain types of portland cement. And commonly, varying countries produce cement types with an assortment of nomenclatures. What are the differences in these cement types and how are they tested, produced, and denoted in practice? This article will look specifically at the differences between U.S. and Canadian portland cements.

In the most general sense, portland cement is produced by heating sources of lime, iron, silica, and alumina to clinkering temperature (2500-2800°F [1400-1550°C]) in a rotating kiln, then grinding the clinker to a specified fineness. The heating that occurs in the kiln transforms the raw materials into new chemical arrangements. Therefore, the chemical composition of the cement is defined by the mass percentages and composition of the raw sources of lime, iron, silica, and alumina as well as the temperature and duration of heating. It is this variation in raw materials source and the plant-specific characteristics, as well as the finishing processes (ie: grinding and possible blending with supplementary cementing materials), that define the cement type produced.

Why the Specifications?

To ensure a level of consistency between portland cement-producing plants, certain chemical and physical limits are placed on portland cement. Depending on the country of production, these chemical limits are defined by a variety of standards and specifications. For instance, portland cements and blended hydraulic cements for concrete in the U.S. conform to the American Society for Testing and Materials (ASTM) specification C150 (Standard Specification for Portland Cement), C595 (Standard Specification for Blended Hydraulic Cement) or C1157 (Performance Specification for Hydraulic Cements). Canadian cements are specified in CSA A3001 (Cementitious Materials for Use in Concrete), which is included in CSA A3000-03 (Cementitious Materials Compendium), invoked by the Canadian Standards Association (CSA). Investigating the differences between these standard specifications helps elucidate the differences in cement properties produced in these neighboring countries.

Nomenclature Differences

Each country employs a different nomenclature for defining the cement types. In the US, three separate standards may apply depending on the category of cement. For portland cement types, ASTM C150 describes:

For blended hydraulic cements – according to ASTM C595 – the following nomenclature is used:

However, with the move in the industry for performance-based specifications, ASTM C1157 specifies cements for their performance:

Cement Type	Description
Type GU	General Use
Type HE	High Early-Strength
Type MS	Moderate Sulfate Resistance
Type HS	High Sulfate Resistance
Type MH	Moderate Heat of Hydration
Type LH	Low Heat of Hydration

Note: For a thorough review of the US cement types and their characteristics see PCA’s Design and Control of Concrete Mixtures (EB001) or Effect of Cement Characteristics on Concrete Properties (EB226).

In Canada, the CSA standard has adopted this performance specification in defining all of its cements. CT041 New Canadian Standard: CSA A3000-03 discusses the new nomenclature for defining both standard portland cement types as well as blended and specialty cements in Canadian provinces. For the French version, click here.

Chemical Limit Differences

Until recently, the largest difference between Canadian and U.S. cements was the inclusion of up to 5% limestone for GU and HE portland cement produced in Canada. However, this limestone addition is now allowed by ASTM and is incorporated into U.S. cements as well. Refer to The Use of Limestone in Portland Cement: A State-of-the-Art Review (EB227).

A comparison between ASTM C150 and A3001 show minor differences in chemical limits. For instance, CSA requires Magnesium oxide level to be 5.0% or less, whereas ASTM C150 allows up to 6.0%. Canadian GU cements can have up to 1.5% insoluble residue; whereas all US cements must meet a 0.75% limit.

Physical Performance Requirements

The purpose of creating varying types of cement is to achieve various modes of action in concrete properties. Just as chemical tests verify the content and composition of cement, physical testing demonstrates physical criteria. Typical physical requirements for cements are: air content, fineness, expansion, strength, heat of hydration, and setting time. Most of these physical tests are carried out using mortar or paste created from the cement type. Canadian and U.S. cements generally possess similar physical requirements for comparable performance characteristics; however, subtle differences do exist. A thorough comparison between ASTM C150, C595, C1157 and CSA A3000 is necessary to capture all of the variants.

Summary

Although the process for cement manufacture is relatively similar across North America and much of the globe, the interpretation of cement specifications can be different depending the jurisdiction. However, the implementation of chemical and physical testing in accordance with an adopted standard makes the comparison possible.

As the use of supplementary cementing materials is expanded, researched, and better understood, the benefits and control of their use is reflected in specifications. With changes in specifications, however, subsequent changes in the technical literature is imminent. See PCA’s Canadian Design and Control of Concrete Mixtures on CD ROM (CD101) for information pertaining to the consolidation of CSA standards A5, A8, A23.5, A362 and A363 into 2003’s Cementitious Materials Compendium (CSA A3000-03).

 
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