Why Is Sand Needed When Mixing Mortar?

Basic Principles

• The inclusion of sand in a mortar mixture is elemental because it makes the binding agent disperse throughout the area being held together. Sand, once combined with either lime or cement, allows for the mortar to be larger in bulk quantity and have the texture of paste. Dry lime and cement are finely ground materials that become smooth once water is added to produce a spreadable mixture. Sand brings bulk and consistency to the mixture, thus allowing for a more tacky and bulky paste to form, which then allows for distribution and spreading.

Lime Mortar

• The addition of sand to a lime-based mortar mix is imperative in creating a finished product less impacted by shrinking as the mortar dries. The right combination of sand, lime and water creates a rugged product that is hearty enough to withstand various weather conditions. The typical combination of materials consists of 1 part lime and 6 parts sand. The lime and sand are mixed with water until a wooden stick can stand upright in the thick mortar. The lime and sand meld with the water to create the paste, and the sand adds bulk to the mortar. Lime mortar is most desirable for projects where slight flexibility of the mortar is required.

Portland Cement Mortar

• The inclusion of Portland cement to a lime, sand and water mixture produces a variation of basic mortar. Portland cement is also sturdy enough to be mixed simply with sand and water for a mortar variation. The ratio of sand to cement, regardless of whether lime is used in conjunction with Portland cement, remains the same. The amount of sand required is five to six times the amount of bonding materials to create the majority of the mixture. For example, 1 part Portland cement, 6 parts sand, 2 parts water and 1 part air create a basic Portland cement mixture.

Masonry Sand

• Regardless of the type of mortar mixture you will be working with or requiring, it is important to use the right sand for the project. Masonry sand ranges from fine-grained to a more coarse consistency. Opting for fine-grained sand results in a smoother appearance of the mortar once dry, whereas coarse-textured sand provides for a more rugged-looking appearance. The choice of sand is dependent upon the project and the end result you wish to achieve.