Sandcrete
Encyclopedia
Sandcrete is a yellow-white building material made from Portland cement
and sand
in a ratio of circa 1:8. It is similar but weaker than mortar
, for which the ratio is circa 1:5.
Sandcrete is usually used as hollow rectangular blocks, often 45 cm wide, 15 cm thick, and 30 cm with hollows that run from top to bottom and occupy around one third of the volume of the block. The blocks can be joined together with mortar.
of sandcrete can be as high as 4.6 N/mm2, which is much less than concrete
's 40 N/mm2. 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. Measured strengths of commercially available sandcrete blocks in Nigeria was found to be between 0.5 and 1 N/mm2, which is well below the 3.5 N/mm2 that is legally required there. This may be due to the need of the manufacturers to keep the price low, and since the main cost-factor is the Portland cement, they reduce that, which results in a block that starts behaving more like loose sand.
There is current research in using organic ash to replace Portland cement, which is better than simply using less Portland cement.
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
and sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
in a ratio of circa 1:8. It is similar but weaker than mortar
Mortar (masonry)
Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar becomes hard when it sets, resulting in a rigid aggregate structure. Modern mortars are typically made from a mixture of sand, a binder...
, for which the ratio is circa 1:5.
Sandcrete is usually used as hollow rectangular blocks, often 45 cm wide, 15 cm thick, and 30 cm with hollows that run from top to bottom and occupy around one third of the volume of the block. The blocks can be joined together with mortar.
Strength and usage
The final compressive strengthCompressive strength
Compressive strength is the capacity of a material or structure to withstand axially directed pushing forces. When the limit of compressive strength is reached, materials are crushed. Concrete can be made to have high compressive strength, e.g...
of sandcrete can be as high as 4.6 N/mm2, which is much less than concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
's 40 N/mm2. 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. Measured strengths of commercially available sandcrete blocks in Nigeria was found to be between 0.5 and 1 N/mm2, which is well below the 3.5 N/mm2 that is legally required there. This may be due to the need of the manufacturers to keep the price low, and since the main cost-factor is the Portland cement, they reduce that, which results in a block that starts behaving more like loose sand.
There is current research in using organic ash to replace Portland cement, which is better than simply using less Portland cement.