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Africa adopts dirt bricks for cleaner construction

Africa adopts dirt bricks for cleaner construction

Oa sunny hill overlooking a valley of shrubs, yellow grass and maize, Deodat Madembwe watches a team of masons make bricks for an elementary school he’s building.

As a young man growing up in central Tanzania, Madembwe too was a mason. Back then the most popular way to make bricks was to mould them loosely out of dirt and clay and then burn them in a tanuru – the Swahili word for a kiln. But to heat the kiln was to wreak havoc on the local environment.

“People cut trees to burn bricks,” he explained. To burn enough bricks for about five houses, they’d have to fell 10, even 20 trees. Burning the trees releases CO², contributing to climate change, and deforestation means there are fewer trees left to combat it. As Tanzania’s population grew, more and more houses arose and the landscape suffered. “We [were] making a desert,” said Madembwe.

But today, on a sunny plateau above Mbeya, the masonry unfolding before Madembwe’s eyes is of an entirely different breed. Two men with shovels quickly mix dirt they’ve sifted with a bit of sand and cement. They add water and shovel the mixture into a small steel device. A third man closes the heavy metal lid and pulls down hard on a long green lever. He releases, and a perfectly rectangular gray brick rises up.

NGOs, governments and local cooperatives have been experimenting with so-called compressed stabilised earth blocks (CSEB), a green alternative to tree-consuming burnt bricks, on a small scale for years. But they may soon rise to global prominence, prompted in part by interest from an unlikely party: the largest cement manufacturer in the world.

The French-Swiss company LafargeHolcim is betting on a product it calls the DuraBric as part of its global push to expand affordable housing. Since 2013 they’ve distributed nearly a dozen hand-operated brick presses around the dusty town of Mbeya, Tanzania, as well as in Rwanda, Cameroon and Zambia. The devices cost about $2,000 each to manufacture, but the company lends them out for free on the condition that users fill them with LafargeHolcim-brand cement.

The process that led to the creation of the Durabric started with an experiment that didn’t work as planned, explains François Perrot, who heads the company’s global affordable housing programme. A few years back the company introduced a low-cost plaster product in India designed to hold mud houses together. But it didn’t sell – people preferred to build new houses with bricks rather than protect their old ones with plaster. Noting this preference, researchers at LafargeHolcim’s R&D lab in Lyon, France, began testing ways to mix cement and dirt for bricks.

Around this time, a continent away, a delegation of government officials in Malawi approached LafargeHolcim looking for a greener alternative to the burnt bricks that were contributing to their country’s deforestation. Suddenly LafargeHolcim had a market for its earth-cement recipe. It quickly furnished a prototype of the brick press and used it to build an NGO-funded school in Malawi’s capital.

When done right, earth bricks are stronger and more weather-resistant than burnt clay ones. Studies have shown that using soil-stabilised bricks to build a home or school can save 20-30% on the project’s overall cost. What’s more, because the bricks are perfectly uniform, homebuilders need to use far less mortar to fill the cracks, and often decide not to plaster the outside of the house. This reduces the amount of cement, the manufacture of which is responsible for around 5% of global CO² emissions.

LafargeHolcim is developing a press to make interlocking bricks, which require less mortar still.

Citing research by a brick-making NGO in India, the company claims that DuraBric blocks release 13 times less CO² than burnt bricks. And it estimates that CSEB emit 20-25% of the CO² of concrete blocks. “It’s a combination between affordable and sustainable,” said Perrot. The cost reduction is a draw for local builders, and he said the environmental benefits are attractive to NGOs. Meanwhile Perrot’s team is working to persuade local government officials to promote the use of DuraBric blocks in public construction projects.

Still, there are challenges. Masons who have spent their entire lives building homes the burnt-brick way must be persuaded and trained to use the machine, and with careful attention to detail: an incorrect ratio of soil to sand to cement can weaken the brick. As we visited DuraBric sites around Mbeya, we encountered piles of bricks left out to dry in the sun that should have been covered by tarps instead – a crucial step that ensures the bricks retain moisture and properly set. Drop one of these sun-dried bricks from waist height and it disintegrates back into dust.

Even well-made bricks won’t last as long if the foundation or the roof is shoddy. “A brick is still 90% soil. It can erode. That’s why you need a good roof and an overhang so it doesn’t rain directly on the wall,” said LafargeHolcim project manager Théophile Balay, who visits each of the machines on a weekly basis to nudge masons in the right direction. The DuraBric is unlikely to sell everywhere. Perrot said that in countries like Morocco people adamantly prefer cement blocks over earthy ones. But elsewhere in Africa, people are recognizing the environmental benefits of the new technique. In fact, the bricks have proven so popular that LafargeHolcim is constructing a factory in Lilongwe, Malawi’s capital city, to manufacture them en masse – as many as 10,000 per day, or enough for two homes.

Jacob Kushner for Sparknews

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  • Kariuki Anthony Kiragu

    Using free appropriate technology to promote cement sales is not a good idea, attributing the background research to India creates wrong impressions and denies the African poor
    technology meant for them.

    Cement stabilized soil block making started in the ‘70’s in Eastern Colombia. Researchers from the Housing Research and Development Unit (HRDU) of Nairobi University met the Colombians at a Manila conference around 1980.

    By 1984 research on Interlocking Stabilized Soil Blocks (ISSB) was steaming ahead at HRDU and eventually came up with the presses seen in the picture shown. I am a witness because I was a 3rd year Architecture undergrad in the same building, still very much in touch with the researchers and have done considerable work in that field.

    Makiga, Genesis and other SME’s in Kenya manufacture and sell these presses at around US $ 1,100, not US $ 2,000, and some buyers put their labels on them. The SME’s have sold hundreds of presses in Uganda, Tanzania, South Sudan, Malawi, Somalia, Rwanda,
    Botswana, Congo and other African countries. Such export is easy because the
    140-Kg press can be dismantled and conveyed by passenger bus or matatu (Dala
    dala)

    Manufacturing the blocks in a factory frustrates appropriate building materials and technology aims because it :

    1. Reintroduces the economic and ecological costs associated with transportation.

    2. Is detrimental to the ecology due to, inter alia, the big quarries that result from a permanent, central production center.

    3. Denies the spread of ISSB and concomitant technology to those it was created to serve.

    4. Brings back the middleman after so much work was done to eject him. As we all know, middlemen live on societal ignorance and, especially in this information age, add no value.

    5. Generally increases capital costs, cuts out the poor and inches the technology towards
    elitism.

    These machines are meant to create employment and shelter for the poor, done by the poor themselves. They were not created to boost cement sales.

    It is several steps backwards and we hope the mooted appropriate technology association to be formed by the Housing Department, Ministry of Lands, Housing and Urban
    Development will stem this kind of misleading activity.

    • François Perrot

      Hi Kariuki, I would say that I agree with most of your points and in particular the social impacts that this technology can have / should keep. I would be glad to clarify some other points by phone if you want to understand how we approach this topic at LafargeHolcim. You can email me at francois.perrot@lafargeholcim.com All the best

    • Elka

      Hmm that’s really interesting for I do understand Africans have been into the mud brick business for ages and this has been the means of building, but trust Africans to always go for the newest shiny thing being cement blocks while not moving forward to innovating the things we have to make our lives easier solar mud blocks etc thatch works, brick tiles, we just have the problem of followers and not leaders in our own strengths. this is our weakness, imagine the names given to our simple mud bricks ISSB long English for much dazzling and we remain dazzled OMG, we need to wake up. these machines are simple machines designed by wielders on the streets of Africa just a strong push and good incentives from our Gov left to move it further. I cant believe people fence their buildings with 100% cement blocks in this Africa cmon. when when plz will this stop, in this case a cement company from France with some big names have to to make a simple technical fact complicated, 90% dirt etc etc, unbelievable, may God save us from ourself’s

  • We have been making cement bricks for ages mixed with pit sand and river sand. I do not know what makes the dirt in the article.

    I think this is one multinational trying to ride on an old idea to sell their cement.

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