The calcium sulfate marketed by GSM is a "synthetic gypsum" that is produced as a by-product of mixing the mineral calcium fluoride with sulfuric acid. This synthetic gypsum is much harder than the naturally occurring gypsum that is used to make wall board. For this reason, the synthetic gypsum performs as an excellent flexible base for roads, parking lots, and storage yards.

Extensive laboratory and engineering studies have been conducted on this synthetic gypsum. The purpose of these studies was directed toward gaining an understanding of the physical and engineering properties of the material and developing specifications for the use of the synthetic gypsum in construction applications. Engineering properties are located at "SUBMITTALS" and material specifications are located at "PRODUCT OVERVIEW".

The Texas Water Commission, the Texas Dept. of Water Resources, and the Texas Dept. of Health have all affirmed that the synthetic gypsum marketed by GSM poses no adverse impacts to the environment. In essence, the synthetic gypsum requires no more special handling than would be required when using crushed limestone or crushed concrete.

Misconceptions

Calcium sulfate can also be produced as a by-product of mixing calcium phosphate with sulfuric acid. However, the calcium sulfate produced from this reaction requires special handling and should not be confused with the synthetic gypsum marketed by GSM.

TxDOT ITEM 247

The synthetic gypsum marketed by GSM is generally accepted as an approved alternate.

Ask the Engineer

Contact: Don Brandon, P.E., 409/550-4165, dbrandon1949@gmail.com