Mortar is a mixture of which materials?

• A. Sand, lime, water, and Portland cement
• B. Sand and lime
• C. Water and lime
• D. Sand and Portland cement

Answer: (A)

Mortar bonds masonry by combining a binding agent with an inert bulk and enough water to make a workable paste. The sand provides the bulk and gives the mortar something to key into the masonry joints. The binders are Portland cement and lime: cement hydrates and hardens for strength, while lime adds plasticity and improves workability and breathability, helping the mortar tolerate slight movement without cracking. Water is essential to hydrate the binders and let the mixture set properly. This blend of sand, lime, Portland cement, and water gives a mortar that is both workable during application and sufficiently strong once cured. Without lime you’d have a cement-only mortar that’s less forgiving; without cement you’d have a lime-sand mortar that’s weaker and slower to set; without sand there’s no proper bulk or joints, and without water the mix won’t hydrate and cure.