Using Bamboo in place of 'Iron Rods' in Concrete - Osaz’ ENOBAKHARE

There are now sufficient reasons to appreciate suitable alternatives in today’s construction. Whether it’s due to cost considerations or environmental factors, exploring alternatives is highly welcomed. Being the world’s most commonly used building material, nearly all our buildings have a signature of concrete on them. Unfortunately, the cost of a cubic-metre of concrete produced in Nigeria has nearly doubled in recent times. The price of iron rods (or steel rebars) is also largely unstable; swinging here and there like a triggered pendulum. 

There seem to be absence of any serious price regulation mechanism and the manufacturers also have their own side to the story – exchange rate issues, increased cost of raw materials, taxation and all sorts. It is not clear whether the building industry has any special provision for the average person or the common man. Interests charged on financial loans are not encouraging. You can go on and on; but complaining is obviously not the solution. They say if life gives you lemons, make lemonades out of it. Here we are; we need to reinforce concrete to maximize its potential and we have got an option –bamboo.

Tested, tried and trusted, bamboo has appreciable tensile and compressive strengths making it suitable for use as reinforcement in concrete. With ultimate tensile strength reaching 124N/sqMM, it only takes a combination of bamboo strands to equal the 250N/sqMM ultimate tensile strength of mild steel and 460N/sqMM  tensile strength of high-yield steel rebars in common use today. More so, provision for bamboo reinforcement in concrete is structurally designed in the same way as steel rebars; the mix ratios and construction processes for bamboo in concrete are not different from the norm, making it not necessarily a change in technology but a change in the material used. It’s that simple!  

There are around 15,000 species of bamboos around the world; the suitable variants are abundant and wasting away in our mangrove forests and elsewhere while we simply look away. There is need to put on a thinking cap and intensify research on the use of the naturally-occurring bamboo which is bio-degradable and eco-friendly than the carbonized steel rods. However just like every other construction material, bamboo has its own limitations; perhaps that is why it has not been approved for use in fully load-bearing members. Does this mean it can’t be used for concrete at all? No!

Bamboos, like several other plants when placed in water tend to absorb it and swell. As it expands in the concrete, it makes the concrete to crack. Water is needed to work concrete and there lies an issue. Researchers have provided solution to curing bamboo to be used in concrete so that it does not absorb water as much as it would normally do.  This treatment can be done right on the site or through other industrial processes before taking the bamboo strands to site. You have to be sure to select healthy brown ones with sizable culms to reduce the cost of treatment. Another worrisome issue was the bonding potential. Naturally bamboo has a smooth surface so it may not bond properly with cement, sand and granite or other aggregates in the mix therefore the strands are often chopped in various sections along its length before they are used in concrete. 

Beyond these two prevailing limitations, what bothers users is the durability of the material in concrete; that’s why it’s not yet broadly applicable for use in fully load-bearing members. As it stands now, the improved variety can be comfortably used for concrete piers, coping and panel of fence walls, lintel beams, ground floor slabs (or ‘German’ floors) in areas with low water table, construction of concrete kerbs, dividers, entrance pavements, wholly in concrete in temporary structures, roof parapets, ground decks, in the construction of low traffic concrete roads and as composite placed side by side with iron rods. Using bamboo as reinforcement slashes the cumulative cost of producing reinforced concrete by almost half. There are no known producers of the improved variety of this material in the country and this also poses an investment opportunity to investors interested in alternative building materials and technology.