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Investigation of the Hardening and Strength Characteristics of Gypsum in Mould Casting for POLY-CRETE

Journal: International Journal of Scientific & Technology Research (Vol.2, No. 12)

Publication Date:

Authors : ; ;

Page : 90-95

Keywords : Keywords polyethylene fibers; poly-crete; asbestos-free; building materials; gypsum-pop composite materials; mould casting; mix ratio;

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Abstract

Abstract Poly-crete is an engineered asbestos-free alternative building material product recently innovated from polyethylene waste materials. Mould design and fabrication is an important step in the final production of prototype 600 mm x 600 mm ceiling boards of Poly-crete. Hardness strength durability and weight of moulds have been found to be directly related to the mix ratio of Portland cement sand aggregate and gypsum plaster of paris- pop used in the production of moulds. It is established in this study through the measurement of hardness on the Mohs Scale and final weight of production trials that a mix ratio of 1 12 sand 34 cement 34 pop by volume produces the best durable mould with a setting time of less than 30 minutes and a hardness of about 3.25. Even though the mix ratio of 2 sand 1 cement 0 pop demonstrated the highest hardnessstrength characteristics with a hardness of about 3.75 it was considered to be too heavy and bulky for routine use. Its setting time of about 24 hours was also considered to be too long cf. 30 minutes for product with 34 pop for its mass production to be economical and profitable. A third mix ratio of 1 12 sand 12 cement 1 gypsum pop also gave a product with a fairly good setting time of about 30 minutes and a hardness of about 3.25. On the other hand a mix ratio of 1 12 sand 1 cement 12 pop took more than 4 hours to setharden and with a hardness of about 3.5. The studies therefore indicate that the addition of pop to a normal sand-cement mix serves to reduce the setting time - that is the mix hardens more quickly though with a corresponding decrease in strengthhardness. Unacceptably long setting time results are obtained with products containing cement in higher proportion than that of pop. In other words the ration of pop in the mixture must be either equal to or greater than that of cement to obtain a short setting time. On the whole however it was found that the mould mix with equal proportion of cement and pop gave the best and optimum mould production in terms of both short setting time and hardnessstrength considerations. This was the case with the mould cast at a mix ratio of 1 12 sand 34 cement 34 pop and is therefore recommended for future poly-crete mould production. It is estimated that a typical SME - Small Medium Enterprise polycrete production factory based on Franchise Business Model would require about 300 moulds for optimal operation.

Last modified: 2014-03-17 17:43:58