Sandcrete is a yellow-white
building material
Building material is material used for construction. Many naturally occurring substances, such as clay, rocks, sand, wood, and even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materials, many man-ma ...
made from a binder (typically
Portland cement
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th ...
),
sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...
in a ratio of circa 1:8, and water. Sometimes other ingredients may be added to reduce the amount of expensive Portland cement such as
pozzolana
Pozzolana or pozzuolana ( , ), also known as pozzolanic ash ( la, pulvis puteolanus), is a natural siliceous or siliceous- aluminous material which reacts with calcium hydroxide in the presence of water at room temperature (cf. pozzolanic reacti ...
s and
rice husk ash. Sandcrete is similar but weaker than
mortar, for which the ratio is circa 1:5. ''
Soil cement'' and ''landcrete'' are similar materials but use other types of
soil
Soil, also commonly referred to as earth or dirt
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
and
hydraform blocks which are compressed, stabilized,
earth blocks.
Sandcrete is usually used as hollow rectangular blocks similar to
concrete masonry unit
A concrete masonry unit (CMU) is a standard-size rectangular block used in building construction. CMUs are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them.
Th ...
s, often wide, thick, and with hollows that run from top to bottom and occupy around one third of the volume of the block. The blocks are joined together with mortar.
Strength and usage
The final
compressive strength of sandcrete can be as high as 4.6 N/mm
2, which is much less than
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
's 40 N/mm
2. Sandcrete is unsuitable for load-bearing columns, and is mainly used for walls, or for foundations if no suitable alternative is available. As material for walls, its strength is less than that of fired clay bricks, but sandcrete is considerably cheaper.
Sandcrete is the main building material for walls of single-storey buildings (such as houses and schools) in countries such as Ghana and Nigeria.
Research has shown using organic ash to replace Portland cement, which is better than simply using less Portland cement.
Coarse aggregate
Addition of
coarse aggregates has been tried, since this is a cheap way to increase compressive strength, but since the cement content of sandcrete is small, so is the amount of water that is added to the sand/cement mix to cure it. Adding more solid materials makes the mix much less fluid, making it difficult to cast into blocks.
References
{{reflist
Soil-based building materials
Cement
Masonry