PCA Research Bulletin 45 concludes with 14 major points related to the effects of periclase, free lime, and C3A on “Hydration Expansion Characteristics” (the bulletin title), but it does not address the easy remedy available for those plants with inherently high MgO.

This paper discusses one practical solution, developed decades ago for a plant without the option of avoiding high MgO levels in the quarry, as well as a control procedure that will help avoid over-doing the chemical modification required and contribute to better uniformity.