Ferro-cement and epoxy mixes

Ferro-cement and epoxy/grp combinations

Either cement on it's own or sand and cement, are mixed with epoxy to create an 'epoxy mortar', is marketed by many manufacturers around the world under various brand names. There are also manufacturers who market it with added shredded glass, carbon fibre and various other stranded materials, used mainly for bridge and building repairs. The mixing of resins and concrete has to be very carefully considered for two main reasons. First their expansion rates are very different. (Steel and a concrete/plaster mix, expand at virtually the same rate). Secondly resin mixes and concrete mixes have reversed osmosis conditions.

There have been many attempts and experiments to improve 'Steel reinforced plaster' (ferro-cement), and 'glass reinforced plastic' (fibreglass), by mixing the two in various combinations. Basically trying to combine the long life and high impact resistance of ferro-cement, with the weight advantage but rapid deterioration of fibreglass. Most of the experiments were done during the 1950's and 60's. The experiments were usually in the vein of either looking for reduction in weight, increased flexibility or increased strength/impact resistance. In the marine world, time proved that there were major drawbacks with resultant osmosis and expansion problems. The former a major obstacle to the use of resins. It is interesting to note that many Scandinavians seem to have taken on the subject almost as a crusade, and some to this day are still experimenting. Although I have to say in general, it still seems to be just covering old ground.

I must point out however that with regard to small areas of repairs the use of epoxy as a compound (not mixed with the plaster), but as an entity attached. Has a place and is acceptable under certain circumstances.

It would certainly be a breakthrough if you could resolve either the heavier weight of ferro-cement, or the rapid deterioration and osmosis problems of fibreglass.

Colin Brookes. mSNAME. amRINA.

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The information and comments given on this 'World Of Ferroboats', website are based on first-hand experience gained by the contributors over many years of use, designing, surveying, building and repairing ferro-cement boats.