Guardian

THE relentless anguished public outcries about the failure to stem the increasing housing deficit in Nigeria blame this failure on the rising costs of building materials among others. Many stakeholders over the past generation see alternative or traditional materials as the only way to reduce rising construction costs. Such stakeholders often use the terms alternative and traditional interchangeably. Many of the materials used in our building fabric are imported, and since frequent currency devaluations increase their costs, many see traditional materials that are less prone to this effect as the solution.

Observers especially seek an alternative to cement, a material that apart from sand is used extensively throughout our local housing fabric. But they forget that cement is a binder that must be used with at least one other material, and can only be replaced when researchers are able to identify another commonly occuring binder. Only two other materials readily come to mind.

Pozzolana is one, hydraulic cement discovered by the Romans and still used in some countries. It  derives from primary deposits of volcanic ash or pumice, predominantly composed of volcanic glass, that are grounded with hydrated lime to make pozzolana.  Since Nigeria is not within a zone of volcanic activity, this material therefore cannot be a substitute. An artificial pozzolana has however been developed that combines fly ash and water-quenched boiler slag. Since slag is not readily available, this therefore also provides us with limited possibilities.

The ash of burnt rice-husk is the other, use of which is gradually gaining prominence worldwide. But, as critics have repeatedly commented, even in large-scale rice-producing countries like India and China this material has yet to surpass use of cement, talk less of Nigeria that still imports an estimated N5 billion worth of processed rice annually. As such, until such a time when a viable alternative emerges, cement will remain the binder of choice in Nigeria.

Importation of most of the cement used locally informed the search for a cheaper alternative.

However, the Director General of Standards Organization of Nigeria (SON) informed the press recently that no new import licenses were issued this year to import cement. This means that the expansion activities of the two major cement producers, Dangote Cement and Lafarge Wapco have succeeded in meeting the demands of the local construction industry for cement. That apart, the two majors also boast they will commence export of cement early next year. Meanwhile, despite this huge increase in supply, the price of cement locally remains at least N1, 500.00 per 50 kilogramme bag, almost twice the N800.00 international price of the same size of cement. So, the cost of cement-based construction locally can fall notably if the cartel of cement producers and suppliers stop conspiring to keep the high cement price solely for their profit but detrimental to local construction activities.

Even though cement production in Nigeria started in 1957 when the earliest cement plant was commissioned, many people do not see cement as a traditional material. A material that has not only been used extensively over the past century to make most of our modern building fabric, and whose essential ingredients, limestone and gypsum are widely obtainable locally cannot but be classified as traditional. In fact, all the local cement producing plants situate variously near large limestone deposits. Cassava is not native to Nigeria, but was introduced here from South America over 200 years ago. Over this time it has become the basic ingredient for many food staples in southern Nigeria including garri, fufu, and amala. If we consider cassava traditional, why not cement?

To reduce house-building costs, other stakeholders are calling for the substitution of sandcrete blocks with cement stabilized laterite solid blocks, and fire-clay bricks with cement stabilized laterite bricks, because both options are purportedly cheaper. This is according to research by Madedor of the Nigeria Buildings and Roads Research Institute (NBRRI) in 1992 and repeated variously since, lately by Aguwa of the University of Technology, Minna. Aguwa claims 30per cent savings using solid cement laterite blocks to build a wall compared to sandcrete blocks. This is doubtful in actual construction because sandcrete blocks contain 11per cent cement content compared to 10 per cent or less in cement laterite blocks, roughly the same amount.

Even though laterite is cheaper than sand, laterite-sand that is most appropriate for cement stabilized blocks is only available at select locations in some states according to Raw Materials Research and Development Council (RMRDC). Transportation thus minimizes the cost difference, putting the 30per cent savings further in doubt. Researchers also claim that solid cement-stabilized blocks have more strength without telling us if this is so for the hollow ones too. Hollow blocks use less material and permit installation of conduit plumbing and electrical wiring.

At the height of the frenzy to build more affordable houses using traditional materials in 2007, President Obasanjo directed the NBRRI to build 500 units of such houses in each state using these laterite-based materials. However nothing came of this directive because, according to NBRRI insiders, the directive lacked cash-backing.

Interestingly, after Lagos became a colony in the 19th Century, imported corrugated iron sheets characterized the earliest domestic building envelopes of the colony (roofs and walls). Walls made of imported fire-clay bricks that were used as ballast on the ships that brought them into Lagos, shortly after replaced iron sheets. By the turn of that century, brick kilns became widespread around Race-Course (now Tafewa Balewa Square) to meet the rising demand for bricks, rapidly growing to become a significant industry especially at a place at Ebute Metta now called Brickfield. Because some of the bricks these kilns produced were not well formed, their use nonetheless, produced poor building outlook. To hide this, masons then plastered over many brick buildings, a fact that is only revealed when these aged buildings are pulled down or fall into dereliction.

With the large-scale introduction of cement into the building industry thereafter, the competitive production of larger sandcrete blocks followed.  Block-walls proved more cost-effective and faster to erect than brick walls even though block-walls require plastering and painting.  Because of the economic advantage and the colour flexibility or other potential finishes of block-walls, brick-walls fell out of favour.  Eventually, brick-walls became decorative alternatives architects used sparingly in constructing the homes of the elite. This remained so until the 1970s, when the economics of new production methods made brick-walls economically competitive with block-walls. This led to the widespread erection of brick factories throughout the federation making bricks readily available for building. But this resurgence did not last for long; by the 1990s brick-walls had again fallen out of favour for unclear reasons, leaving behind many abandoned brick factories.

Other materials touted as promising to build homes cheaply include fibre-reinforced roofing sheets, bamboo-reinforced concrete floors and interlocking blocks. A radically impressive effort used these materials to build a terrace of three housing units in the late 1980s on a university campus. Time has however not proved these materials durable. Less than a decade later, long-span roofing sheets have replaced the fibre sheets. Research also showed that the bonding strength between bamboo and concrete in bamboo-reinforced concrete floors reduces with time making such floors liable to failure under heavy loads. The mortar-less external interlocking block-walls did not prevent water penetration into interiors from driving rain, ultimately requiring plaster and paint finish.

Hydraform, a company producing a machine that cheaply makes solid cement stabilized bricks and blocks in Nigeria and elsewhere, similarly claim that their units firmly interlock to form walls without mortar. But examples of buildings they advertise using these materials are usually low-height buildings with eaves that protect interlocking masonry walls from driving rain. Suspicion however lingers about using these materials in the walls of multi-floors buildings exposed to driving rain.

Without the emergence of any notable alternative material to build affordable homes over the past generation, the search continues. Thankfully, SON has contributed to reducing the cost of materials by lowering the minimum permissible thickness of galvanized corrugated iron roofing sheets from 0.30 to 0.15millimetres as in Ghana. But are alternative traditional building materials truly viable to reduce housing construction costs?