Weight Reduction Study Of Polycrete-An Asbestos-Free Building Material Product
Keywords: polyethylene fibers, polycrete, asbestos-free, building materials, composite materials, mix ratio
ABSTRACT: Motivated by the dual need of developing alternative non-carcinogenic building material products from local raw materials and the need for sustainable solid waste management of polyethylene packaged water sachets waste in Nigeria, an asbestos-free composite material, polycrete, viable for use as ceiling and partitioning boards in buildings was recently developed by the author. The technical viability of forming a durable composite material from polyethylene fibers (shredded/granulated polyethylene sachets- poly-fibers), and cement in durable economic mix ratio of 1:4 by volume (i.e. one part of cement with 4 parts of fiber) was established with test specimens cast in plastic moulds as presented at RETAV Conference 2009, at Obafemi Awolowo University, Ile-Ife, Nigeria. In order to meet workability requirements (for easy penetration of nails), some amount of paper was also added to introduce some ductility to the mix. Building on the success of initial trials with model specimens, prototype ceiling boards, 600mm x 600mm in size are now being investigated for production. Replicating the mix ratios as established for the model specimens in the prototype production, final product weight of 4.4kg per piece was achieved. It was considered desirable to reduce the weight per product to about 3.5kg so as to be comparable with lighter ceiling products made from gypsum (Plaster of Paris - POP). Various combination weights of Portland cement, poly-fibers, waste paper, and water were varied with the objective of producing a 600mm x 600mm prototype with a product weight not exceeding 3.5kg. This paper presents results of the trials and establishes a minimum weight of 2.5kg Portland cement, 0.5kg poly-fiber, 0.1kg paper and 2.25kg of water to produce a 600mm x 600mm by 5.0mm thick ceiling board with a product weight of 3.35kg. Production process was replicated several times with durable prototypes being formed each time. A comparable asbestos-cement ceiling sheet (produced by Nigerite - 1.2m x 1.2m x 3.5mm thick in dimension - four times the surface area of polycrete product) weighs 8.0kg. In addition to the asbestos-free attribute of polycrete, other obvious advantage of Polycrete Decorative Ceiling board over the Nigerite product is the artistic pattern design embossed on it, making it aesthetically more pleasing to home owners than the plain version of Nigerite product.
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