Certifying a Portland Cement to ANSI/NSF Standard 61
Some manufacturers of Portland cement (the main ingredient in concrete) have obtained Certification to ANSI/NSF Standard 61 to ensure that their products are safe for contact with drinking water. NSF Certified tank coatings are almost always required in bid specifications, but it is much less common for Portland cements to be specified in bids as NSF Certified. Yet concrete is commonly used in distribution piping and water storage tanks.
Most state regulations require that
water contact products comply with ANSI/NSF Standard 61. This ensures that one of the most prevalent water contact materials in water treatment plants will be safe. The responsibility thus falls to water utilities and their
contractors and consultants to specify certified cements.
To obtain certification, Portland cement manufacturers submit a full formulation disclosure to NSF, including the formulation of grinding aids used in the processing of cement clinker. The disclosure specifies whether hazardous waste fuels are burned in cement kilns during the manufacturing process.
NSF toxicology staff reviews the formulation of the cement and develops an analytical test plan to detect potential contaminants of concern. This includes regulated metals analysis by ICP/MS, organic chemical analysis by GC/MS, radionuclide, dioxin, furan, and formulation-specific analyses for compounds such as glycols and ethanoloamines.
An NSF auditor verifies the raw materials and their suppliers at the production facility, reviews quality control records, and collects samples for laboratory analysis.
Cement mortar tubes are fabricated and exposed to pH 5 and pH 10 exposure waters for regulated metal analyses, and at pH 8 for organic analyses.
As a final step, toxicology staff gather test data and compare them to established Maximum Allowable Levels (MALs) for each contaminant. If the cement meets the requirements of Standard 61, the product packaging can bear the NSF Mark.
Because concrete is used so extensively in the water industry, it is important that utilities specify NSF Certified Portland cements to encourage others to take the necessary steps to protect the quality of drinking water.