Interlocking technology

As Kenya’s population grows, the Government and other stakeholders have emphasised on efficiency and speed in putting up affordable houses to fulfill the constitutional stipulation of the right to shelter.

Owing to the appropriateness of interlocking technology and its sustainability in use of local materials, the Government, through the Ministry of Transport, Infrastructure, Housing and Urban Development, has pushed hard for its use in providing affordable housing.

This falls under the Appropriate Building Materials and Technology (ABMT), as promoted by the Kenya Building Research Centre (KBRC), covering easily sourced materials in specific areas that are also environmentally friendly.

The Government’s effort and the private sector’s investment have, in recent years, witnessed an uptake of appropriate technologies, including Precast Concrete Panels, Compressed Agricultural Fibre (CAF), Monolithic Construction, Expanded Polystyrene, Interlocking Stabilised Soil Blocks (ISSBs), Interlocking Concrete Blocks, Pre-fabricated Housing, Recycled Waste Plastics, Bio-digester Onsite Sewer System, Integrated Bio-digester and Bio-gas System, Concrete Waffles and use of Light Gauge Steel.

This comes as Kenya increasingly ditches the traditional wattle and mud structures, as the fast-growing construction industry swallows cement and timber products in millions of tonnes. The Ministry is at the same time seeking more private investors and innovators to present information for inclusion on its website.

Interlocking Concrete Blocks (ICB) This type of technology is gaining currency in the country, given its durability and cost-saving attributes during construction. The blocks are made using quarry dust or laterite powder and gravelly.

According to the makers, a 50kg bag of cement can make around 50 interlocking blocks. In total, they can be manufactured using 4,000 kilogrammes of compress, making them strong enough.

The blocks, unlike the baked bricks, are compressed under high pressure with some chemical additives to raise the strength. They are also heavier than baked bricks.

Since the cost of building a house with interlocking bricks is quite affordable, many homeowners are now embracing the technique – sparking a new trend that is likely to bridge the housing demand-supply gap in the country.

A major scoring point of the concrete interlocking block is cost saving. Each block is made to interlock and normally uses minimum cement and sand to conjoin, unlike normal stones that are uneven and unwieldy. Needless to say, the builder saves a fortune by not employing labour to smoothen them. The standardisation also makes it easy to build with them.

The blocks are environmentally friendly as no rubble is left on the site, besides being more durable due to uniformity. The latter also lowers the maintenance cost. In the context of mass affordable housing, the technology cuts the duration of construction due to the light work of joining blocks. It also features customised designs. Apart from building of walls, they have gained currency as paving blocks, commonly called Cabro in Kenya. Interlocking Stabilised Soil Blocks. One of the sustainable and affordable technologies the Government has been encouraging developers to adopt, is the Interlocking Stabilised Soil Blocks, whose raw material is readily available in most counties.

It mainly uses soil, meaning it can be utilised on small scale in most rural areas, efficiently addressing the twin national problems of affordable housing and poverty eradication. Besides, the blocks are cooler, cheaper (typically no transport costs) and environmentally friendly — saving land from ruinous quarrying — than stone buildings. The materials include small amounts of sand and cement, and mostly soil. Its proper use, according to Government research, can cut the cost of housing by half, while creating structural employment and transfer of skills. It is reckoned to conserve the environment while raising the standards of living, particularly in rural areas, partly explaining the Ministry’s investment in disseminating this information to potential users.

NHC has invested Sh1 billion in the construction of a prefabs factory in Machakos County, with a capacity to produce 126,720 expanded polystyrene panels a year. In 2014, IGS unveiled a Sh851,400 house built using panels made from compressed wheat husks targeting low income earners.

Government agencies have carried out research on appropriate building technology of stabilised blocks with the University of Nairobi, an acknowledged pioneer through its phased out HABBRI arms. Research eventually led to the Kenya Bureau of Standards (Kebs) gazetting KS 02-1070 for stabilised blocks way back in 1993. In 1995, an additional code 95 was gazetted.

Nevertheless, municipalities and their successors, the counties, have not adopted the standards, meaning there has not been widespread use of the technology, even as 60 percent of the urban population lives in poorly constructed slums. That notwithstanding, individuals and groups in rural areas have been adopting the technology for homes and community projects development, sometimes at the instigation of a few non-governmental organisations (NGOs).

According to Aidah Mumano, a senior ministry official, uptake in rural areas is now at 15 percent, compared with one percent in 2010. The Ministry has attributed the poor uptake in part to the absence of harmonised regulatory framework and poor interest from the built-environment professionals, more tutored in brick-and-mortar construction.

Rural area players, a major target of the technology, lack relevant skills to take up the appropriate technology. But steps are being taken to address this situation, both at the policy and devolved levels. Legal action includes the Housing Bill, the Revised Building Code, the National Building Regulations and the Built-Environment Bill that, once enacted, will plug the vacuum currently dragging development of the relatively novel technology.

On the ground, supply of manual press machines will be scaled up, according to KBRC, to enhance both reach and usage. The National Housing Development Fund, under the National Housing Policy, will be critical in enhancing supply of the relevant machinery to the affordable social houses builders.

At the urban level, the Ministry of Housing established ABMT Centre at Mavoko, Machakos, which abuts the fast-growing centres of Mavoko, Kitengela and Machakos. Some nine sub-Regional and 73 sub-County ABMT centres have also been put up across the country, all aimed at quick delivery of the technologies.

The centres are set to deliver through helping formulate and update the regulatory frame of the technology, and collaboration in research among the stakeholders. They will prepare a Memorandum of Understanding on the research, technology incubation and capacity building among the collaborators.

They will help produce periodic reports on the technological uptake, besides benchmarking with the best local and international practices. Other functions are the development of curriculum, training, facilitation of production of cheap local building materials, monitoring and implementation of adherence to standards, and dissemination of information.

Apart from small-scale makers of interlocking soil blocks, there are mega manufacturers like the Thika Road-based Kenya Clayworks. As for ICB, dozens of manufacturers, like Panda Bricks, Optiven and Makiga Engineering Services, are in production. The latter also supplies machinery for making stabilised soil blocks.



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