New eco-friendly building blocks use dredged river mud and dry in the sun rather than needing coal or wood to bake them
By Mosabber Hossain
DHAKA, Nov 8 (Thomson Reuters Foundation) – Researchers in Bangladesh are developing new building materials to mitigate the environmental damage caused by brick manufacturing.
The country produces 25 billion bricks every year. According to Mohammad Abu Sadeque, head of the Dhaka-based Housing and Building Research Institute, meeting this demand requires excavating 60 million tonnes of topsoil, causing dust pollution and degrading the ground.
Brick kilns also consume 5 million tonnes of coal and 3 million tonnes of wood annually, in the process emitting 15 million tonnes of carbon into the air, Sadeque said.
His institute, which is part of the Ministry of Housing and Public Works, has spent three years developing a range of alternative, environmentally friendly building materials for walls, floors and roofing.
Experts say the new materials will reduce environmental pollution and cut construction costs, while also making buildings more earthquake resistant.
The products include a brick made of a compressed composite of river mud and cement. The bricks do not require firing in a kiln, but simply harden in the sun.
The new bricks are also lighter than traditional ones, making them easier and cheaper to transport.
Dredging riverbeds for the mud to produce the new bricks will help preserve topsoil, Sadeque said.
M. Inamul Haque, chairman of the Institute of Water and Environment Sciences, acknowledged that dredging can harm aquatic creatures, but said that many rivers had to be dredged in any case to remove sediment, improve their flow and stave off flooding.
Conventional dredging machines are able to remove the mud required for the bricks, he added.
According to the Housing and Building Research Institute (HBRI), each brick costs 6 Bangladeshi takas ($0.07) to produce, compared with a cost of 11 takas for traditional bricks.
The institute has also developed a range of blocks, thermal blocks, wall panels and paving stones.
Although the new materials are not yet commercially available, the institute has constructed a five-storey demonstration building with them on its premises.
Last year, the new bricks also were used to build a primary school in the Nalitabari area of Bangladesh’s Sherpur District.
That one-storey building was 30 percent cheaper than one made with conventional bricks, Sadeque said.
The bricks for the school were produced using a machine that can be transported to where the mud is excavated, lowering costs further.
The machine can manufacture nearly 7,000 bricks a day, and the institute plans to use it for mass production of its building materials.
Brick kilns in and around Dhaka are responsible for a big share of the densely populated capital’s air pollution, according to research conducted by Bangladesh’s Department of Environment in association with the Norwegian Institute for Air Research.
Altogether there are more than 1,000 brick kilns in and around the capital, researchers said. The kilns produce nearly 60 percent of Dhaka’s air pollution, with the rest coming from dust and vehicles, along with other sources, they said.
Syeda Rizwana Hasan, chief executive of the Bangladesh Environmental Lawyers Association, said authorities should amend the Brick Production and Brick Kiln Building (Control) Act of 2013 to take into account the pollution, damage to agricultural land and other environmental threats caused by brick production.
Under Bangladesh’s current five-year plan, the government is committed to reducing air pollution to zero by 2020.
Experts hope other government institutions involved in construction will push for wider public use of the new construction materials.
Jamilur Reza Chowdhury, an engineer and the vice-chancellor of Asia Pacific University in Dhaka, said that a range of national and international companies should be encouraged to produce more environmentally friendly building materials.
Several are already doing so, including the CONCORD Group of companies, which manufactures pavement blocks and bricks for walls and roofs, and Mir Ceramics, which produces environmentally friendly tiles for flooring, walls and stairways.
The Housing and Building Research Institute says that almost 20 businesses have expressed interest in commercially producing the bricks and blocks developed by the institute.
“If people want to learn environmentally friendly technology, we are ready to provide training,” Sadeque said.
Hasan Latifur Rahman, general manager of business development at Building Technology and Ideas Ltd, a property development company, said his company had constructed more than 60 buildings in Dhaka and Chittagong, Bangladesh’s largest industrial city, using environmentally friendly materials and support from HBRI.
“When we make people understand the harmful effects of the soil-burning blocks, they get interested to use these (new) blocks,” he said.