NRMCA, ASCC Article Examines Issues Concerning Concrete for Slabs on Ground

NRMCA Executive Vice President, Engineering, Colin Lobo recently partnered with technical representatives at the American Society of Concrete Contractors (ASCC) to author an article for ACI Concrete International magazine that addresses whether concrete used for floor slabs should be assigned to the durability exposure classes of ACI 318 and thereby comply with those requirements. There are some exposure conditions whereby the requirements for concrete would require a lower w/cm than typically used in practice and recommended by ACI Committee 302 on floor construction. Using concrete with a low w/cm could impact constructability and the ability to obtain the required finish and comply with floor tolerances.

In this article, it is suggested that concrete floor slabs constructed on a capillary break subgrade layer and on a vapor retarder are adequately isolated from exposure to sulfates in soil and suggests that these do not need to be assigned to the exposure class for more severe sulfate resistance. Testing performed on simulated systems and evaluation of preserving the integrity of vapor retarder sheets are used in this article to support the suggestions.

The article, Vapor Barriers Used with Capillary Breaks Reduce the Severity of Sulfate Exposure of Concrete, by James Klinger, Bruce Suprenant and Colin Lobo is published in the August 2021 issue of ACI’s magazine.

For more information, contact Colin Lobo at clobo@nrmca.org.