Turning newspaper mill waste into lightweight bricks…..Garima Mishra
Two Nagpur-based researchers and their team are working on the design and development of the lightweight brick that is made with newspaper mill waste
Two Nagpur-based researchers and their team are working on the design and development of the lightweight brick that is made with newspaper mill waste
When two Nagpur-based researchers made a casual visit to a paper recycle mill in 2009, never did they imagine that the visit will turn into a unique innovation and a full-fledged project. The researchers and their team are currently working on the design and development of the lightweight brick that is made with newspaper mill waste. When we visited the mill, we found that the sludge is just piled around the mill and solid waste material is landfilled. We thought about making better use of this waste and came up with the idea of making bricks using this sludge. I assigned this task to my undergraduate students as a summer project in 2009, said Sachin A Mandavgane, associate professor, department of chemical engineering, Visvesvaraya National Institute of Technology (VNIT), Nagpur. The result was a lightweight brick that is made with 90 per cent paper mill waste and 10 per cent of cement.
Based on the results, VNIT researcher Sachin Mandavgane, Pr S S Gokhale, director, VNIT and Dr S S Bhagade of Laxminarayan Institute of Technology, Nagpur filed for patent. Once the idea was conceived, Prof S S Gokhale, director VNIT and B D Kulkarni, a distinguished scientist from National Chemical Laboratory, Pune, conceptualised the project and gave guidance for execution. The project, which is headed by Mandavgane is funded by the Department of Science and Technology, SEED Division, under young scientist scheme. Assisting him is Rahul V Ralegaonkar, associate professor, VNIT.
A variety of waste material has been used in the production of this lightweight brick. For instance, the use of paper processing residues, cigarette butts, fly ash, textile effluent treatment plant (ETP) sludge, polystyrene foam, plastic fibre, straw, polystyrene fabric, cotton waste, dried sludge collected from an industrial wastewater treatment plant, rice husk ash, granulated blast furnace slag, rubber, kraft pulp production residue, limestone dust and wood sawdust, processed waste tea, petroleum effluent treatment plant sludge, welding flux slag and waste paper pulp. Recycle Paper Mills (RPM) contribute 30 per cent of total pulp and paper mill segment in India. With 85 per cent being the average efficiency of RPM, 5 per cent waste (RPMW) is produced annually. RPMW which otherwise is land filled has been utilised to make construction bricks that serve a purpose of solid waste management, new revenue generation and earning carbon credits, said Mandavgane.
The brick requires homogeneous mixing of recycle paper mill waste and cement. Waste being fibrous in nature, for mixing, a shear mixer was required. Efficient removal of moisture and drying was another challenge that was overcome with successive mechanical compression and solar drying. The developed brick can be used as internal partition wall, for fall ceiling and making temporary hutments. Its special application could be as thermal insulator and sound absorber. Due to its light weight, the application of bricks in earthquake prone areas is under study. The group is planning to make a model house with these bricks that will give an idea about its age. We will be able to judge its physical properties, thermal properties, fire tolerance and so on, said Prof Gokhale.
In the mixing process of samples, RPMW and cement contents are placed in a specially designed and fabricated mixer and mixed for 2 minutes. RPMW being fibrous in nature and lumpy, the blades of the mixer are designed to shear the RPMW mass every time it rotates. In order to obtain more homogeneous mixes, the water is sprayed by air pump onto the mixes while the mixer is turning. Another 5 minutes of mixing is done. Later, the mixes are fed into the steel molds and remain in the mold till initial moisture is removed. The brick is taken out and kept for solar drying. The semi-dried brick is further pressed till its moisture content is reduced and is then kept for final sun drying. The test results show that the RPMW-cement combination provides results which can be potentially used in the production of lighter and economical new brick material. Speaking about the bricks suitability for long term, Kulkarni said, Its a meaningful project as it takes care of a varieties of wastes. Besides, the technology and the process involved in the making of the brick should create immense rural employment in future.
The brick making procedure being simple can be undertaken as rural entrepreneurship by unskilled
labourers of developing countries, added Mandavgane. There are a few shortcoming though, Mandavgane said. One is its high water absorption ability. We are putting water proof coat to overcome this.
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