GEMS – Growth and Employment in States
We are pleased to report that Coffey International and the UK government are moving forward on a plan to improve the concrete block in Nigeria. This effort is identified as GEMS2. The following are some excerpts from their plan to improve the concrete block supply chain. We will publish the findings of this pilot program as we get them.
The frequent collapse of buildings in Nigeria has been attributed to two main causes: the poor quality of construction work and the inferior quality of building materials. The Nigerian system of building is masonry (building of structures from individual units laid in and bound together by mortar) and the common material of masonry construction in Nigeria is hollow concrete block. Deaths by building collapse in Lagos have been reported as recently as January 1, 2013.
Concrete (also known as sandcrete) blocks are made from cement, sand, aggregate, and water. The cement market in Nigeria totaled 17.1 million tonnes in 2011, worth approximately $4 billion at market prices. Dangote Cement, Nigeria’s dominant cement manufacturer, estimates that 50% of cement demand is driven by residential construction, as concrete blocks are far and away the most common structural material used for home-building in Nigeria. A 2004 report concluded that over 90% of physical infrastructures in Nigeria are constructed using sandcrete blocks.
The most common sizes of concrete blocks in Nigeria are 6’’ (6” x 9” x 18”) and 9” (9’’ x 9’’ x 18’’); The price of concrete blocks fluctuates with the price of of the main cost input, Cement.
Concrete blocks used in Nigeria are all made locally. The vast majority of concrete block makers in Nigeria are small and medium private enterprises; there are literally thousands of small-scale block makers nationwide; the National Association of Block Moulders of Nigeria (NABMON) estimates 200,000. You can see them along the roadside any time you drive through Lagos.
The quality of concrete blocks used in Nigeria is mostly very low, contributing to building collapse. Although the Standards Organization of Nigeria (SON) has established standards for concrete blocks, most of these small and micro-scale block makers do not adhere to any established quality standards and few, if any, have documented manufacturing processes or quality assurance systems in place. In the field study conducted by Anosike and Oyebade in 2012, all the blocks sampled from four Nigerian manufacturers failed to meet SON standards. In particular, all blocks sampled were well below the specified values in compressive strength for load-bearing walls, some blocks bearing as little as one-fifth the specified load. However, blocks made under controlled conditions did meet SON standards.
Block quality is dependent on these major factors:
- Use of the proper proportions of all components (portland cement, water, sand and gravel)
- Accurate measuring of all the components
- Consistent and adequate blending of the mixture
- Sufficient watering and drying of the blocks
- Molds that meet the block specifications (i.e. dimensions)
In Nigeria, there are four primary block quality problems:
- First, in terms of proportions, the quality of the blocks is better with a higher ratio of cement to sharp sand, but because of its high cost, block makers reduce the quantity of cement and end up with lower-strength blocks. Anosile and Oyebade cite cases where the specified 1:8 cement-to-sand ratio is reduced to 1:12.
- Second, laborers in Nigeria typically use buckets and shovels to measure the quantities of components that go into the concrete mix, resulting in imprecise/inaccurate measurement.
- Third, quality also depends on whether the components are mixed properly, meaning the aggregate is blended 4-5 times. The current practice in most small and medium enterprises is that the laborers mix manually with shovels, resulting in inconsistent mix and therefore sub-standard blocks.
- Fourth, water should be used in correct proportion, but to make shovel mixing easier, too much water is often added which reduces the quality of the end product.
Practically all small-scale block making companies in Nigeria resort to shovel measurement and mixing.
There are some transit-mix suppliers in Nigeria, but there are problems with using standard mixers for block production. The relatively dry mixture required for concrete blocks does not lend itself to conventional drum mixing methods like those found in the truck mixers.
GEMS2 discovers the issues with concrete block
GEMS2 conducted interviews with some major stakeholders in the construction industry in Lagos and the F.C.T., Abuja. Some further issues were identified:
- Lack of enforcement by the Standards Organization of Nigeria (SON): Though they have the responsibility of checking and ensuring material quality, due to various resource limitations and irregularities they cannot enforce the standard requirements of block quality.
- A largely price conscious population: The population generally lack knowledge about quality, so other than large scale industrial clients, most customers prioritize cost over quality.
Improving awareness about block quality and more widespread use of higher quality block among end customers is an ambitious long-term goal which will only be effective after product quality is actually improved. GEMS2 can affect block quality by influencing and improving the small scale block making process through a pilot project that introduces on-site batch-fed mixers to Nigeria. This technology has been used to solve similar problems elsewhere in the world but has not yet been introduced into Nigeria. The portable batch mixer uses measured boxes to insure a consistent recipe of concrete ingredients. A paddle mixing auger then turns and blends the mixture much better than shovels. The mixer is powered by a small generator which allows it to be used in the field. The equipment is relatively simple to maintain and operate and its use does not displace manual labor.
Pilot project includes batch-fed mixers
The pilot project is based around the introduction of small scale batch-fed mixing technology to Nigeria. The introduction of this relatively low-cost technology, simple for unskilled laborers to use, can gradually foster the widespread improvement of block quality throughout the concrete block industry. The batch-fed mixer produces consistent mixes from a unique yet simple batching process that shovels alone cannot produce. It not only measures the materials that enter the mixer accurately but also blends and mixes the inputs uniformly. The technology also eliminates the constant supervision required to ensure that laborers manually mix the aggregates the required number of times before adding water to the mix. It is portable and designed for small and medium sized sites.
Batch-fed mixers will lead to consistent production of better quality concrete blocks, allowing small and medium scale operators to differentiate their products by quality. The differentiation will eventually lead to market uptake of the ready-mix technology as users realize the benefits of using better quality block and give a larger share of their business to block makers employing the technology. This same technology can be used in the production of other concrete products such as interlocking tiles. If the pilot is deemed successful, the project can be replicated in other parts of Nigeria.
GEMS2 will provide the technology and assistance to run the pilot project, while National Association of Block Moulders of Nigeria (NABMON) in Lagos and/or Afro Blocks in Abuja will host and operate the first pilots. If the pilots are successful, the hosts will permanently adopt the technology and expand use of batch-mixing in production of their concrete blocks. GEMS2 will require the pilot hosts to invite other block making companies to view the pilot project in operation.
The expected output of the pilot projects is not only better quality concrete blocks, which in and of itself does not serve our program objectives, but also more efficient production which directly leads to higher incomes for block making laborers since they are paid by output. The number of laborers affected could reach into the thousands based on NABMON’s estimate of 200,000 block moulders. The means to earn higher incomes through selling better quality blocks with a modest investment would attract crowding-in, a quantum step in the technology that raises the bar for block makers.
The idea of better quality can spread
Once a few blocks moulders start to see the financial benefit from improving production techniques, other producers will also emulate this model, which can induce an industry-wide systemic change. Also, when builders and contractors gradually notice the consistent quality difference in the concrete blocks made with this process versus those produced through shovel-mixing, there will be a heightened demand for such concrete blocks/products. Demand can be stimulated through awareness programs targeted at users, and eventually private sector certification of block quality. SON does currently have responsibility for certification but their enforcement capability falls far short.
MORE TO COME…