Q. We are in the preliminary stages of bidding on what designers hope to be a Leadership in Energy and Environmental Design (LEED) structure. We are considering developing a “green” concrete mix design using blended cements. In our research, we discovered there have been recent changes to the ASTM standards for blended cements.

What were these changes?

A. Interest in blended cement products has been increasing, with many producers finding these premixed cements useful in customizing mix designs. Experts define blended cements as “portland-based cements that include supplementary cementitious materials (SCMs), such as ground granulated blast furnace slag, fly ash, or other pozzolans, such as silica fume or meta-kaolin.” Delivered as a premixed blend, producers need to only use one silo in their plant.

Recognizing this increased use, ASTM C 595-06, Standard Specification for Blended Cements, was released in August 2006 with some important changes to nomenclature. The committee responsible for the specification simplified the document, hoping to make it easier to use. The committee also wanted to eliminate a problem with producing cements near the boundaries.

For example, under the previous standard, the old Type IP cement contained between 15% and 40% pozzolan, while a Type I(PM) cement contained between 0% and 15% pozzolan. These definitions made it almost impossible for a manufacturer to produce a blended cement with about 15% fly ash, since as with normal process variation, it would sometimes be classified as a Type IP and sometimes a Type I(PM).

To solve this, the new standard eliminates both classification types. They were replaced by Type IP(X) classification, where the X stands for the nominal percentage of the SCM included in the blended cement. For example, a cement designated as Type IP(20) contains 20% pozzolan by mass.

This change will facilitate communication between the cement suppliers, producers, and engineers for quantifying the amounts of SCM in concrete mixes. It will help producers when considering adding SCMs on projects where the mix may be subject to restrictions on the total amount of SCMs in the concrete.

Here is a summary of the changes found in the new document:

  • Type I(PM), I(SM), I(PM)-A, I(SM)-A, and S were eliminated.
  • New portland-pozzolan cement, Type IP(X), can include between 0% and 40% pozzolans, replacing old Types IP and I(PM).
  • New portland blast furnace slag cement, Type IS(X), can include between 0% and 95% ground granulated blast furnace slag, replacing the old Types IS, I(SM), and S.
  • The letter X stands for the nominal percentage of the SCM included in the blended cements.
  • This topic was recently covered in the December 2006 edition of Concrete Technology, published by the Portland Cement Association (PCA) and is the source of some of the information contained in our reply.

    E-mailed six times a year, Concrete Technology includes the latest edition of Concrete Technology Today in alternate issues, information on materials, concrete topics, common questions, industry resources, and news on current events in the cement industry. To subscribe to this free newsletter visit the PCA at www.cement.org, or e-mail info@cement.org.

     
    Spec Watch

    There have been several changes and updates in important ASTM standards affecting concrete producers. Committee members approved five new ASTM Standards at December's ASTM committee meetings. Here is a brief update on these changes:

    C114 – Standard Test Methods for Chemical Analysis of Hydraulic Cement has been revised to C114-06.

    C1252 – Standard Test Methods for Uncompacted Void Content of Fine Aggregate (as Influenced by Particle Shape, Surface Texture, and Grading) has been revised to C1252-06.

    C1622/C1622M – Standard Specification for Cold-Weather Admixture Systems has been revised to C1622/C1622M-06.

    C511 – Standard Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes has been revised to C511-06.

    C76 – Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe has been revised to C76-06.

    To help producers learn about these and other new standards, ASTM's Web site includes a document summary page. You can access all of this information by visiting www.astm.org. You only need to enter the standard designation number, such as C1207, in the site search.

    The ASTM staff also announced that committees are beginning discussions on four work items. They are:

    WK13439 – Test Method for Total Sulfur in Concrete.

    WK13453 – Standard Specification for Liquid Membrane-Forming Compounds Having Special Properties for Curing and Sealing Concrete is a work item revision to existing standard C1315-06.

    WK13455 – Standard Test Method for Determining Consistency and Density of Roller-Compacted Concrete Using a Vibrating Table is a work item revision to existing standard C1170-06.

    WK13475 – Standard Specification for Packaged, Dry, Combined Materials for Mortar and Concrete is a work item revision to existing standard C387/C387M-06a.

    Producer involvement in these standard discussions is vital. To learn how to become a committee member, telephone ASTM at 610-832-9585 or e-mail service@astm.org. The staff will direct you to the appropriate committee chairman.