Cassava Technology: An Alternative Form of Cement
Pius Sawa Murefu
Kampala, Uganda - Oct 2007
Extensive research carried out on cassava (Manihot Esculenta) has concluded that the starch contained within it can be used to bond bricks i.e. used as cement in the construction of buildings.
Katende Harambe is a rural-urban training centre located about thirty kilometres east of Kampala. It is a five hectare piece of land containing sixteen projects focusing on different areas such as; horticulture, biogas generation, rain water harvesting, pesticide production, bee keeping, the rearing of pigs, poultry, goats, rabbits etc.
Aimed at accelerating wealth through sustainable integrated farming, Katende Harambe is teaching rural farmers how to utilize their land to fight poverty. “Cassava technology came about as a result of farmers inability to afford the cost of constructing buildings for both their shelter and that of their farm animals,” says Joel Ssekimpi, an administrator.
Two to three kilos of cassava flour mixed with two wheelbarrows of sand and twenty litres of cooled (previously boiled) water make a potent mortar. A kilo of cassava flour in Uganda costs Ugsh 300 the equivalent of $0.17. This means one will spend no more than half a dollar on cassava flour to mix two wheelbarrows of sand. A bag of modern conventional cement costs Ugsh 25,000 i.e. $14.70. It can be utilised to mix only three wheelbarrows of sand. The difference is self explanatory.
Cassava is a widely grown crop in Uganda as well as for other uses, farmers are also being advised to grow, harvest and process it for use in construction as cement. Depending on the soil type, a well grown acre of cassava can produce up to one hundred bags of cement. Masaka and Koboko districts are favourable cassava growing areas. Ssekimpi says the technology is being adopted by low-income earners for house building in rural areas but also even in towns and cities.
However its use does require training, and special care should be taken so that it does not ferment or get eaten by cassava pests. Special training should be undertaken on the laying of bricks and mixing of mortar. He says only three layers of bricks should be constructed per day.
How to control pests:
Because at Katende Harambe farming is purely organic, pesticides are organically manufactured. To guard against attack by cassava pests, buildings in which cassava based cement is utilised should be constructed away from bushes or gardens. Having said that, the most successful control of pests is by insect repelling plants. “We have two types; Tephrosia spp and phytolaccae spp. They are locally known as Muluku and Oluwoko respectively, and farmers are well aware of them.” Says Ssekimpi. These plants repel a wide range of pests.
It is not advisable to use cassava flour for the foundations of buildings due to a lack of cost effective solutions to control pests underground. It is annoying to see that while eighty percent of Ugandans depend on farming to earn a living most of them are badly housed yet they grow cassava all year round.
Potentially many people with land can afford to make bricks and collect sand. The high cost of modern conventional cement has been problematic. This technology will go some way to readdressing the balance.