Building using unique interlocking blocks made from recycled plastic

plastic blocks

A godown for storing medical supplies built using interlocking plastic blocks. 

Photo credit: Pool

When Joseph Kirumba set out to recycle plastics, his primary goal was to clean up the environment. He embarked on a journey that started with lots of research and sleepless nights trying to figure out how he would recycle what no one else was recycling.

In the recycling world, there are seven types of plastics, and recyclers are quite selective with what they put back into circulation. But Kirumba was not going to take the same route. Before he set up his production factory, Constructive Plastics Limited, in 2019, all he had was an idea and a 3D printed prototype of a plastic construction brick. Four years down the line, he has created a unique product - the only of its kind in Kenya - an interlocking plastic block made from a combination of all types of plastic, including nylon paper, gunny bags and carrier bags.

The block can almost be confused with a regular quarry stone with its grey, rustic appearance, but its workability contrasts brick and mortar construction sharply. With its interlocking capacity, it eliminates many of the other materials and construction processes. Is the construction industry opening up to this novel way of building? DN2 Property had an illuminating chat with Kirumba.

How did you get involved in recycling plastics?

Initially, I wanted to clean up the environment. Plastics having been piling up on our roads, sidewalks, in our homes, ditches and in rivers. I had a strong desire to do something about it. Recycling plastics is not a new concept, so I researched a lot, looking into the possibilities of what else can be produced using plastics. I settled on products for the construction industry because it was a brilliant way to solve multiple problems. I come from central Kenya, and growing up, we enjoyed seeing the vast forests. But within just a few years as the population grew, people cut trees rapidly to build houses. Over time the forests disappeared. The transition is shocking. These are some of the factors that influenced my decision to create a cheaper building material to replace wood and other costly materials that pollute or degrade the environment.

plastic blocks

Hannigton Ochieng' places molten plastic on a hydraulic press to be pressed into bricks in Nairobi on February 24,  2021. 

Photo credit: Francis Nderitu | Nation Media Group

Take us through your journey, from idea conception to creating a tangible brick.

My journey started with consulting with architects of Architekturburo Hermann Beyer and engineer Karl-Heinz Pietschmann while I was in Germany. We came up with a 3d printed prototype for a plastic interlocking brick. In 2019, I decided to set up a factory here in Kenya. I started looking for an ideal location for the factory. Being a new business model selling a product that has not been produced or sold in Kenya, I needed a place that will mitigate the risks of a young business. This proved to be the first big challenge.

Godowns in the most popular locations are not cheap. Bearing in mind that I only had a prototype and was yet to produce the actual brick, it was too risky to set up in a pricey location. After searching for a while, an old friend took me to Kariobangi Light Industries. I realised it was very conducive. There were people collecting, sorting and crushing plastics in the area and it was right in the middle of key plastic collection points. Kariobangi is the heart of recycling.

What about machines, were they easily available?

Recycling has been done by others and there are machines for the critical processes such as crashing and melting. But what I did not factor in was that my product was different. From the beginning, I knew I was going to make my moulds to produce the exact shape of brick I wanted. But my recycling process turned out to be different from the kind of recycling that is commonly done. I needed extra machines and I had to get innovative. There is no factory in Kenya recycling in the exact same way that I can visit and benchmark. I had only bought two machines but I ended up making several other machines. For example, I recycle all types of plastics, unlike other recyclers who only recycle specific types of plastics out of the seven types available, I recycle indiscriminately, including carrier bags and gunny bags. I had to design a mixing to combine all the plastics before melting.

interlocking plastic blocks

A godown for storing medical supplies built using interlocking plastic blocks. 

Photo credit: Pool

Interesting! Where does this knowledge on building machines come from and how have you managed to recycle all types of plastics?

I guess I was born an engineer. I was always dismantling things as a child and I enjoyed the process of rebuilding them. Plus there are machines all around us and I can easily borrow ideas. The mixer is inspired by food mixers and blenders. On recycling all types of plastics, when I started this, I did not want to compete with those already recycling the most popular types of plastics. I wanted to take care of every other plastic left out of the circular economy. Besides, some of the popular plastics are very expensive because everybody wants them. Remember, I wanted to build a block that is cheaper than what people are using to build, so if I buy competitive, expensive plastics as my raw materials, the model would be unsustainable. To figure out how I can integrate all types of plastics, I had to research, consult and experiment a lot. My research journey led me to Material Scientist and researcher Dr Kennedy Ogila. He had been researching on plastics for a while and my idea to create a plastic building block was a perfect opportunity for us to share notes. Before I built my first block, we started testing how different plastic types behave and recorded the observations. It was an exciting process. Eventually I was able to come up with a formula to work with.

When did you produce your first building block?

A year later, in 2020, I was able to produce the first block. I invited the people I had consulted earlier to see it. It was a wonderful experience before I realised that I now had to figure out how I was going to build with the block. It is one thing to create an interlocking block in a factory and another to build an actual wall with it. I built several structures to test the block and it worked out.

Kirumba Muita

Kirumba Muita is an environmentalist.

Photo credit: Pool

Who was your first client?

I met someone who had an urgent need to build. She owns a school. She needed to build new classrooms urgently as they were moving to a different location that could not accommodate all their learners. They wanted nice, decent classrooms as soon as possible and they could not go for the usual brick and mortar building process. It would take too long and the noisy building process would disrupt learning. They needed a quiet and fast method. When we met and I explained how the plastic interlocking block works, it was as if it was built for their need. With the block, we did not need machines, just a hammer and a little bit of drilling here and there. In four weeks we had built four classrooms and a lab.

How is the general reception so far and what else have you created?

Everyone who has seen the blocks and what they can achieve is surprised and impressed with the outcome. So far we've built different types of structures. From the classrooms to watchmen houses, litter bins, fencing poles and paving blocks. The first litter bin I built was for Michuki Nature Walk. It had not crossed my mind that the blocks would end up building litter bins but we did it. The blocks are flexible and they can be reconfigured to build anything. I had also offered to build multiple bins for the Nairobi County Government for free through the Nairobi Metropolitan Service. Being the headquarters of United Nations Environment Program, I felt like we need to walk the talk. We can't fight dumping, instead, we can curb it with strategically placed bins. Unfortunately, those plans did not materialise.

What is your biggest success story four years on?

Producing the first block. When I held this first block in my hands I knew I could build anything. All the nights I stayed awake experimenting and wondering whether the block would be stable enough or whether it would work on a construction site were answered when I produced the first one. Interlocking blocks were invented a long time ago, but the plastic prototype I had in mind, especially one that was built with recycled plastics had not been achieved.

Seeing how people appreciate the product I have built is also rewarding. I built a toilet in Githurai and everyone who comes across it is impressed, and they do the marketing for me through word of mouth.

What kind of concerns or questions have people presented to you?

Most people imagine that the brick is a light weight type of plastic that can be cut with a knife, but once they see it and feel how heavy and strong it is, they are shocked. We've tested it against quarry stones and it is way stronger.

About cost, how is the plastic block reducing the cost of construction?

The greatest advantage is the time factor. It takes a short time to build using the plastic block because it interlocks. In addition, we do not need to use so many additional materials such as cement, sand or water in the construction process. Of course, it requires less labour, and that automatically cuts down on the overall cost. The only additional cost is the regular concrete foundation. We work with architects and other construction experts, just like in other projects. We integrate their ideas when constructing. So far I haven't met anyone who is unable to work with it.

The recycling industry is growing quite fast, do you foresee a future where used plastic will be in such high demand like the scrap metal industry and the possibility of plastic being scarce?

We have a lot more plastic than we can handle. We've noticed plastics that were banned in Kenya are still in circulation. Plastic is one of the biggest inventions, and right now it is used in every industry. Almost every product is packed in plastic and it is as if we cannot live without it. The problem is so advanced, even the fish we eat are eating micro plastics and they end up in our bodies. Right now, our need to reduce plastics is still urgent. We are a long way from running out of plastic.

For a long time, recycling companies have focused on reproducing single household products. Do you think the construction industry provides promising opportunities for the plastic problem?

In some of the developed countries, plastic has been integrated in tar used in tarmac roads. The construction industry is definitely the next big home for recycled plastics. So far the materials we are using to construct are degrading the environment. Sand is harvested from rivers which are being depleted and it is becoming scarce. Plastic can solve these problems.