Bamboo Can Replace Iron Rods as Reinforcement in Beams

Government's dream of providing housing for all may become reality sooner than later following research work by some researchers in the Dept. of Civil and Environmental Engineering, University of Lagos.

In this chat with Dr Efe Ikponmwosa, a senior lecturer in the Dept. of Civil and Environmental Engineering, University of Lagos, he speaks on the efforts so far made in bringing down the cost of building by using locally and readily available materials. Excerpts:

Substitutes for Iron and Steel Reinforcements:

Dr. Efe Ikponmwosa said they have done a lot of research into innovative local materials that could be used as substitutes either for reinforcements in concrete structures or as pozzolans for partial replacement of cement. "We concentrate more on agricultural wastes and also work on industrial wastes that constitute problems in the environment.

We (I and my mentors - Prof. M.A. Salau, Dean, and Prof. Funso Falade, former HoD, Department of Civil Engineering) have concentrated on a material like bamboo. We have done lots of work on bamboo and I can assure you today that I can build a house in such a way that I can use bamboo as my reinforcement instead of iron rods for all my beams.

We have also investigated the use of the same bamboo reinforcement for columns (pillars), although investigation has revealed that for very critical constructions like multi-storey buildings, it is not advisable to use bamboo in the columns."

Low cost housing scheme

According to Ikponmwosa, these materials are good for low-cost houses. "For the so-called low-cost housing schemes, especially those that are outside the central business districts; may be rural communities and outskirts of town where bamboos are readily available, you can use bamboo as reinforcing bars in your beams.

We have tested it and we know that up to about four metres of beam can be handled with bamboo. What it means is that I can construct all my beams in a three-bedroom low-cost house without using reinforcing bars, rather, I will use treated bamboo, dried, well seasoned, mature bamboo," he stated.

Describing the process involved, the Russia-trained engineer who specialises in Materials & Structures stated that the bamboo is first of all sliced into strips like the size of a rod but in this case, it will be square (10mm x 10mm or 10mm x 12mm). They are then dried and treated with bitumen or some other things. This has given up to 20 per cent savings.

"Apart from bamboo, we have other materials in that family. They are called natural fibre reinforcements. Examples are coconut tree trunk and palm tree trunk. For instance, if a coconut or palm tree gets too tall, it is usually cut down.

In this case, the trunks can be cut into lumps and you slice out your reinforcements. These can be used in rural communities. If someone is putting up a small house, the research centres can help them season the fibre reinforcements to build their little bungalows. All they need do is to come into town and buy the links (metal rings) to hold the reinforcements together," he said.

Partial replacement for cement:

"We have also looked at pozzolanic materials. These are non-cementitious materials on their own but when they are in a medium that makes them wet, like water and with cement around them, they tend to exhibit cementitious properties. So in that case, we can have partial replacement of cement with pozzolans in order to cut cost.

We have been able to see that in rice-producing areas, rice husks are burnt into fine ash because they are agricultural waste. We can have some quantity of it as partial replacement for cement. It does not endanger your structure in any way and that could also help in cutting costs," he stated.

Waste to Wealth: "We look for industrial wastes which abound and tend to constitute problems. Their handling costs a lot of money so we look at ways of recycling them by having them used as partial replacement for either cement or the fillers. We are working on Nigerite roofing sheet waste right now. We have always known that they constitute problems in the industry.

They will heap them and after some time, they spend about N5, 000 - N10, 000 per truck and also pay the Lagos State Waste Management Agency (LAWMA) to dump it at the dump site. So we are investigating if they could be recycled into production of building components, may be even in concretes.

If the results are reasonably positive, all the company will require is to have a small milling machine and periodically, they will just mill the waste into fine powder, mix with other building components like sand and you can mould them into blocks or whatever, for housing panels.

It all depends on how people think it out. That way, you are minimising waste to be handled by the waste management agency and at the same time, creating value from the waste.

"We have worked over the years on slags from the steel industry. They are wastes that constitute problems. If you go to Acme Road in Ikeja, you see that they keep on having that slag and after sometime, they have to pay people to break them into lumps, and carry them to the dump site. Again, we are looking at ways they could be recycled.

***SOURCE: Vanguard Newspaper dated 1^st March. 2012