NIST reaffirms commitment to cement industry. (News Briefs).

NIST portland cement Standard Reference Materials (SRMs) have underpinned product quality for the cement industry for nearly 50 years. The cement SRM 1880 series has proven to be essential to laboratories which certify concrete products for performance and which evaluate mechanisms for concrete corrosion and failure. NIST has recently completed re-certification of the entire suite of 10 cement SRMs in the 1880 series in collaboration with a subsidiary of the Portland Cement Association, and the U.S. Geological Survey.

The replacement series of cement SRMs reflects newer cement types now being used; ordinary and blended portland cement products from around the world were selected, including blends with limestone, slag, and fly ash, low Fe white cement, and two calcium aluminate cements. These materials are certified for more components that cover a wider range of elemental composition than any prior series. Four of the certificates of analysis of the new SRMs carry a table of results from the Cement and Concrete Reference Laboratory Proficiency Sample Program operated by NIST, which summarizes proficiency test results from over 200 laboratories.

A key development of the project was a matrix-independent x-ray fluorescence method created by a NIST scientist, in which calibration standards are prepared from primary reference materials using borate fusion. Major, minor, and trace constituents can be determined without corrections for matrix effects, which typically lead to high relative uncertainties in the final results. This new high performance method consistently yields expanded relative uncertainty estimates below 1%. In addition to cement, the versatile method has already been applied to zeolite compounds, low alloy steel, and aerospace alloys.

CONTACT: John Sieber, [phone]; [e-mail] or Bruce MacDonald, [phone]; [e-mail].