SAND

Sands and aggregates are natural products used in the production of mortar and concrete. They are usually excavated from locations where ancient river and sea beds were re-formed during the early periods of the earth’s structure. The term ‘aggregate’ is a generic one used to describe gravels, stones and sharp sand, which are mixed with cement and water to make concrete

SAND

Fig. 20 Soft red sand.

 

SAND

Fig. 21 Soft yellow sand.

 

Sand

In order to ensure consistency of mortar colour, always obtain sand from one source only for each building project.

 

The terms ‘fine aggregate’, ‘concreting sand’ or ‘sharp sand’ describe the natural sand, crushed stone or similar that passes through a 5mm sieve but tends to be coarser and

 

not as well graded as the sands used in mortars. It is often referred to as ‘fine aggregate’ to distinguish it from soft sand. Being coarser than soft sand, it is not used for mortars as it produces an unworkable mix and causes difficulties with achieving a good finish when jointing. The sand used for mortar is referred to as ‘soft sand’ (or sometimes ‘builders’ sand’), as distinct from the fine aggregate (also known as ‘sharp sand’) used in the mixing of concrete.

Soft sand should be well graded, as poorly graded sand will require a greater amount of cement binder to fill the gaps between the grains. This will cause the mortar to shrink more, creating drying shrinkage cracks in the mortar joints and at the junction between the mortar joint and brick.

Like aggregates for concrete, sands can be purchased in 25-kg bags, 1-tonne ‘dumpy bags’ or loose by the lorryload. Soft red sand tends to produce mortar that is brown in colour whereas soft yellow sand produces grey mortar.