In the next in a series of features on building materials,
Sachin Mandavgane, Associate Professor of Chemical Engineering, VNIT, tells us how newspaper mill wastes can help produce speciality bricks for the construction industry.
Recycled paper mills contribute 30 per cent to the total pulp and paper mill segment in India. With 85 per cent being the average efficiency of these mills, 5 per cent waste is produced annually. In an era where going green is the new mantra, imagine this waste, which is otherwise land-filled, becoming a source of carbon credits! In 2009, two researchers from Nagpur instructed their undergraduate students to scout among the paper industries and document their observations. The end result: lightweight bricks. Sachin Mandavgane, Co-researcher and Associate Professor of Chemical Engineering, Visvesvaraya National Institute of Technology (VNIT), tells us exactly how this came about in conversation with
Shriyal Sethumadhavan.
IdeationOur primary focus remained on two aspects: determining the best possible way to utilise the solid waste generated from recycled newspaper mills and conducting research at an undergraduate level. In and around the recycled paper mill industry, we found an acre of land filled with waste generated from recycled paper. I decided to investigate further how we could best utilise this ample solid waste. Being light in weight, this waste eventually helped us produce lightweight bricks. Apart from this, at present, we are also working on waste generated from the cotton industry, ash and other fibre, where we are partially replacing conventional cement with the material. But the bricks produced here are for speciality applications 鈥� the basic thrust is thermal comfort. Even lightweight bricks made from paper are thermally insulated; they have sound absorbing properties.
A team effortIt took us one year in the lab to try and test different combinations, discover the right technique and, finally, develop the lightweight bricks. Based on the results, VNIT filed a patent. Prof SS Ghokale, the then Director of VNIT; BD Kulkarni, a distinguished scientist from the National Chemical Laboratory, Pune and Dr SS Bhagade of Laxminarayan Institute of Technology, Nagpur conceptualised the project and guided us in terms of execution. While Rahul Ralegaonkar, Associate Professor of Civil Engineering, VNIT, co researched the civil engineering aspect of the project, I contributed to the material development and testing part. In 2010, we approached the Department of Science and Technology of the Government of India with a complete proposal and it decided to fund the project. It gave us almost Rs 23 lakh and, within the next two years, we developed our technology. And finally in 2012, we are ready.
The processBasically, in terms of moisture content, a typical consistency is required from the recycled paper waste collated. According to our research, 70-75 per cent is the ideal moisture content required; if the moisture content exceeds this or is lower, mixing could be a problem. Once the right moisture level is determined, we have a specially designed mixture that acts as a shredder and shears the pulp with every rotation. The process includes constant cutting and mixing; we look at a homogeneous mixture of binding material, which is cement and paper mill waste. We determined that 10 per cent cement and 90 per cent recyclable paper waste is the ideal proportion.
Once the mixture is prepared, we put it into a brick making machine, which is specially designed considering that the solid waste may contain almost 70 per cent moisture. Essentially, a method had to be devised to separate water from the mixture and there are two ways to do this. First, the water can be squeezed by compression. But this could have a negative impact on the drying of the brick. So, we separated the water by compression using a brick making machine and dried it through solar energy.
Payment modeAs the paper industry is considering this as waste at present and does not realise its product value, we do not have to pay for it. We can prepare around 5,000 bricks from 3 to 4 tonne paper waste. So as far as raw material is concerned, we have not commercialised these bricks and hence, the raw material is free of cost. The only area that incurs some cost is overhead charges, digging of the waste and transportation. However, one major advantage is thermal comfort. We have two identical test rooms in the VNIT department. In one room, we used conventional false ceiling material, which cost us around Rs 100 per sq ft, including the material. Adjacent to that, in a second identical room, we used our own material which cost us around Rs 40-44 per sq ft. Both ceilings are standing equally strong. Thus, it is evident that this material will be very affordable for the construction industry.
The ideal userTypically, as academicians, our role involves introducing a product that is tested for economic feasibility with properties that are on a par with international and Indian standards. Hence, if anybody is interested in adopting this technology and making it commercial, we will definitely share it with them. We are looking for manufacturers who would like to adopt the technology and start producing these bricks. If builders and contractors opt for it, they will have to search for the raw material.
It is very rare that you approach an industrialist and things materialise. Until and unless they are emotionally attached to the project or convinced that it is viable and will give good returns, they do not show much interest. At present, we have two potential clients: the paper mill industry as it generates this waste and has acres of landfill; and self help groups (SHG) in and around the paper industry. The technique we have discovered is comparatively simple and the equipment designed is hand-operated. So this could be another option for revenue generation for people in rural areas in and around the industry or the paper industry itself. However, as far as aesthetics are concerned, to make the product saleable, the manufacturer will have to work on the product design.
Other waste materialsWe are also looking at alternate materials like rice husk ash, sugarcane bagasse, and plastic and cotton waste. However, in terms of the products that can be generated from these, we are still in the research stage. Even if they are not lightweight, these waste materials should help us generate speciality bricks with some other added feature. As we offer some additional features, we do not wish to draw comparisons with conventional bricks. So, with these new waste materials, we are concentrating on making bricks that will act as a false ceiling material. This is my primary area of application.
Pros and consThese bricks have their own disadvantages 鈥� one problem is to join two bricks; the second, their water absorption properties. So these materials would be most suitable for internal applications like partition walls and false ceilings in homes and offices where there are not exposed to the outside environment.
Last year, in August, we created a model prototype on the terrace of our institute with these bricks. It's over a year now, and it has withstood the high temperature of Nagpur as well as the rains. But here, we also adopted the ferro-cement technique. This is a known composite where chicken wire mesh is used as the reinforcement in a dense cement mortar mix.
However, the major challenge lies in proper mixing because the raw material is derived in the form of pulp. Second, making the brick itself was a challenge initially as, once we moulded it, the dry surface of the brick would get deformed. Hence, we decided to adopt a two-stage method where we first compressed it and then dried it through solar energy. Finally, there was the issue of water absorption. However, now we are using water insulating solutions to overcome this.
Lifecycle costA frequently asked question is the lifecycle cost. The answer is simple: we made our oldest brick in 2009; it still stands strong. It is non-biodegradable and does not erode. Also in terms of compressing strength, it has high compression energy absorption ability. However, there is often an apprehension amongst the masses that we are using waste to construct their home. We hope this thought does not have a negative impact on decision making. And if it does, it would be an unfortunate victory over the advantages of this product.
Share your experience with any construction material at
[email protected]
In the next in a series of features on building materials, Sachin Mandavgane, Associate Professor of Chemical Engineering, VNIT, tells us how newspaper mill wastes can help produce speciality bricks for the construction industry.Recycled paper mills contribute 30 per cent to the total pulp and paper mill segment in India. With 85 per cent being the average efficiency of these mills, 5 per cent waste is produced annually. In an era where going green is the new mantra, imagine this waste, which is otherwise land-filled, becoming a source of carbon credits! In 2009, two researchers from Nagpur instructed their undergraduate students to scout among the paper industries and document their observations. The end result: lightweight bricks. Sachin Mandavgane, Co-researcher and Associate Professor of Chemical Engineering, Visvesvaraya National Institute of Technology (VNIT), tells us exactly how this came about in conversation with Shriyal Sethumadhavan.IdeationOur primary focus remained on two aspects: determining the best possible way to utilise the solid waste generated from recycled newspaper mills and conducting research at an undergraduate level. In and around the recycled paper mill industry, we found an acre of land filled with waste generated from recycled paper. I decided to investigate further how we could best utilise this ample solid waste. Being light in weight, this waste eventually helped us produce lightweight bricks. Apart from this, at present, we are also working on waste generated from the cotton industry, ash and other fibre, where we are partially replacing conventional cement with the material. But the bricks produced here are for speciality applications 鈥� the basic thrust is thermal comfort. Even lightweight bricks made from paper are thermally insulated; they have sound absorbing properties.A team effortIt took us one year in the lab to try and test different combinations, discover the right technique and, finally, develop the lightweight bricks. Based on the results, VNIT filed a patent. Prof SS Ghokale, the then Director of VNIT; BD Kulkarni, a distinguished scientist from the National Chemical Laboratory, Pune and Dr SS Bhagade of Laxminarayan Institute of Technology, Nagpur conceptualised the project and guided us in terms of execution. While Rahul Ralegaonkar, Associate Professor of Civil Engineering, VNIT, co researched the civil engineering aspect of the project, I contributed to the material development and testing part. In 2010, we approached the Department of Science and Technology of the Government of India with a complete proposal and it decided to fund the project. It gave us almost Rs 23 lakh and, within the next two years, we developed our technology. And finally in 2012, we are ready.The processBasically, in terms of moisture content, a typical consistency is required from the recycled paper waste collated. According to our research, 70-75 per cent is the ideal moisture content required; if the moisture content exceeds this or is lower, mixing could be a problem. Once the right moisture level is determined, we have a specially designed mixture that acts as a shredder and shears the pulp with every rotation. The process includes constant cutting and mixing; we look at a homogeneous mixture of binding material, which is cement and paper mill waste. We determined that 10 per cent cement and 90 per cent recyclable paper waste is the ideal proportion.Once the mixture is prepared, we put it into a brick making machine, which is specially designed considering that the solid waste may contain almost 70 per cent moisture. Essentially, a method had to be devised to separate water from the mixture and there are two ways to do this. First, the water can be squeezed by compression. But this could have a negative impact on the drying of the brick. So, we separated the water by compression using a brick making machine and dried it through solar energy.Payment modeAs the paper industry is considering this as waste at present and does not realise its product value, we do not have to pay for it. We can prepare around 5,000 bricks from 3 to 4 tonne paper waste. So as far as raw material is concerned, we have not commercialised these bricks and hence, the raw material is free of cost. The only area that incurs some cost is overhead charges, digging of the waste and transportation. However, one major advantage is thermal comfort. We have two identical test rooms in the VNIT department. In one room, we used conventional false ceiling material, which cost us around Rs 100 per sq ft, including the material. Adjacent to that, in a second identical room, we used our own material which cost us around Rs 40-44 per sq ft. Both ceilings are standing equally strong. Thus, it is evident that this material will be very affordable for the construction industry.The ideal userTypically, as academicians, our role involves introducing a product that is tested for economic feasibility with properties that are on a par with international and Indian standards. Hence, if anybody is interested in adopting this technology and making it commercial, we will definitely share it with them. We are looking for manufacturers who would like to adopt the technology and start producing these bricks. If builders and contractors opt for it, they will have to search for the raw material.It is very rare that you approach an industrialist and things materialise. Until and unless they are emotionally attached to the project or convinced that it is viable and will give good returns, they do not show much interest. At present, we have two potential clients: the paper mill industry as it generates this waste and has acres of landfill; and self help groups (SHG) in and around the paper industry. The technique we have discovered is comparatively simple and the equipment designed is hand-operated. So this could be another option for revenue generation for people in rural areas in and around the industry or the paper industry itself. However, as far as aesthetics are concerned, to make the product saleable, the manufacturer will have to work on the product design.Other waste materialsWe are also looking at alternate materials like rice husk ash, sugarcane bagasse, and plastic and cotton waste. However, in terms of the products that can be generated from these, we are still in the research stage. Even if they are not lightweight, these waste materials should help us generate speciality bricks with some other added feature. As we offer some additional features, we do not wish to draw comparisons with conventional bricks. So, with these new waste materials, we are concentrating on making bricks that will act as a false ceiling material. This is my primary area of application.Pros and consThese bricks have their own disadvantages 鈥� one problem is to join two bricks; the second, their water absorption properties. So these materials would be most suitable for internal applications like partition walls and false ceilings in homes and offices where there are not exposed to the outside environment.Last year, in August, we created a model prototype on the terrace of our institute with these bricks. It's over a year now, and it has withstood the high temperature of Nagpur as well as the rains. But here, we also adopted the ferro-cement technique. This is a known composite where chicken wire mesh is used as the reinforcement in a dense cement mortar mix.However, the major challenge lies in proper mixing because the raw material is derived in the form of pulp. Second, making the brick itself was a challenge initially as, once we moulded it, the dry surface of the brick would get deformed. Hence, we decided to adopt a two-stage method where we first compressed it and then dried it through solar energy. Finally, there was the issue of water absorption. However, now we are using water insulating solutions to overcome this.Lifecycle costA frequently asked question is the lifecycle cost. The answer is simple: we made our oldest brick in 2009; it still stands strong. It is non-biodegradable and does not erode. Also in terms of compressing strength, it has high compression energy absorption ability. However, there is often an apprehension amongst the masses that we are using waste to construct their home. We hope this thought does not have a negative impact on decision making. And if it does, it would be an unfortunate victory over the advantages of this product.Share your experience with any construction material at [email protected]
