In a recent study that was conducted in Sri-Lanka, a comparison between mud bricks and hollow cement blocks, modern fired clay bricks plus laterite bricks revealed that mud bricks were the most eco-friendly and the most affordable of the four.
According to the study, obtaining the raw materials needed for mud bricks do not harm the environment and at the end of a structure’s lifespan, the bricks easily disintegrate and are assimilated back into the soil.
Making the bricks, though labour intensive, is simple and does not require any specialized skills. The materials are mixed together then cast into moulds made of wood or metal and slowly dried in the sun for at least two weeks.
The process does not require pricey, hi-tech tools and equipment, making the mud bricks one of the cheapest construction materials in the market.
During construction, the bricks are joined together using an earth mortar to form a wall whose surface is later smoothed out using a clay render to give it a neat finish.
Besides the usual vertical walls, sun dried mud bricks can also be used in the construction of curved structures such as vaults and domes.
The slow drying process gives the bricks strength which enables them to be used in the building of structures up to several storeys high, if the walls are laid with the appropriate thickness.
The bricks have many advantages including being cheap to produce, durable, biodegradable, fireproof, good acoustic insulators and good thermal insulators which save on heating and cooling expenses.
“Why spend more money and destroy the environment more?” asks Rangika Halwatura, a civil engineer at the University of Moratuwa in Sri Lanka, and one of the authors of the paper.
Although the bricks have a good level of water resistance due to the nature of clay soil and the production process which hardens them, the walls are still susceptible to destruction due to excessive moisture therefore adequate protection from rainfall in form of eaves should be provided.
The use of mud bricks in building has been in practice since ancient times with evidence showing structures dating back to 8300 BC built using the technique.
There are buildings made of mud bricks, estimated to be 900 years old and still in use to date which means that with the proper construction and care, the walls can last for centuries.
Today, the use of mud bricks has been fused with modern technology where concrete and cement are incorporated in the blocks to improve their strength. They are also produced with holes for reinforcement and services.
Besides, foundations for mud bricks walled houses are being constructed using concrete to prevent capillary of ground water which can destroy the first courses. Cement is also being used as mortar and as plaster to give the houses a smooth modern look.
Countries grappling with housing shortages due to the high cost of materials and skilled labour can employ this technique for low cost self-built units where bricks can be produced in situ if materials are available or purchased from commercial brick makers.