Bond strength and flexibility work together, holding masonry units in place yet flexing in response to lateral loads or expanding and contracting in response to temperature swings. To achieve the balance of properties for a particular application, you mix different proportions of portland cement, hydrated lime, sand and water. Portland cement yields greater compressive strength but lower water retention during the cure, thus risking shrinkage cracks. Lime yields lower compressive strength but greater bond strength and flexibility. Sand, the aggregate, adds volume and minimizes shrinkage as the cement dries.
Water makes the mix workable and activates hydration, the chemical reaction that hardens the cement.
Type N is recommended for most exterior, above-grade walls exposed to severe weather, including chimneys. Used by permission. Read our Privacy Policy .