There are currently an estimated 13,000 end of life boats in Holland, a figure that one prediction says is set to rise to an astonishing 75,000 by 2030. In France 500 boats were dismantled last year however there is still a backlog of at least ten to fifteen years. The International Council of Marine Industry Associations (ICOMIA) has estimated that there are more than 6 million recreational craft in Europe alone; so expect the problem to only worsen.
These are just some of the quantities affecting the industry the METSTRADE Sustainability in the Marine Industry conference was told in late 2016. But industry leaders also heard how some progress is now being made with end of life boats – albeit on a limited scale. Clearly this is a subject that has been exercising Albert ten Busschen for some time. A chance meeting at an IIMS event in Holland recently led to the commissioning of this special article on this important subject - the elephant in the room some would say. Albert has found a novel and practical use for end-of-life boats and writes passionately about the problem, his methodology and solution.
Growing number of obsolete polyester yachts
There is a growing number of obsolete boats coming from the recreational vessel fleet. This is a direct result of the number of boats that were acquired during the seventies and eighties of the last century when it became fashionable to own a yacht. On top of that, nowadays the demand for second-hand models is very low as boat ownership has gone out of fashion with the younger generation. Boat owners therefore dispose of their old boat either by taking it to a boat dismantling
company or just abandon it. The disruptive potential is enormous as already some Dutch canals are blocked by orphaned boats.
Boat dismantling companies remove the useful parts from a boat like the mast, stainless steel parts, the motor, the propulsion system and authentic parts like hard-wood steering wheels and brass window frames. These parts can be sold. However, the remaining boat hull and cabin are worthless and end up as landfill for which additional costs have to be made. The majority of these hulls and cabins are built from glass fibre reinforced polyester composite, GRP, or popularly referred to as ‘polyester’. In The Netherlands alone the volume of these End-of-Life (EoL) polyester boat parts came to 1,400 tonnes in 2015 and will grow to 4,000 tonnes per annum in 2030.
Primary recycling is not an option
For the past two decades the composite industry has been working on the recycling of composite products. Several efforts have been made to regain the raw materials: reinforcing fibres and plastic. A recent comprehensive overview has been given by the ACMA in 2016 [1]. This so-called primary recycling, meaning regaining the original components of which the material is composed, appeared not to be successful. Besides the low quality of the recycled components, these methods never became economically viable. At the moment the so-called ‘cement- kiln route’ is the accepted route by the European Union as a recycling method for composites, although only the caloric value (combustion energy) and the silicium dioxide present in the EoL thermoset composite are regained in a cement oven [2]. This ‘cement-kiln
route’ is clearly also not a form of primary recycling but moreover, as with primary recycling it has not been economically successful.
The solution: structural re-use
The principle of the structural re-use of EoL composite products is based on the use of oblong elements gained from EoL composite parts embedded in virgin material. In this way, the good properties that are still present in the EoL composite products (high mechanical strength and resistance to water) are put to good use in the new composite. This methodology, which was financed by a government grant, was developed by the Professorship for Polymer Engineering of Windesheim University of Applied Sciences, The Netherlands. Contrary to primary recycling where raw material components are regained, this method leaves the composite structure as it is and falls in the category of secondary recycling.
To achieve a maximum strength contribution of the oblong elements of the old composite, a high fill rate is desired and, therefore, the amount of virgin embedment material (resin) needs to be limited, this also from an economical point of view. Because of their shape, the elements contribute to the reinforcement of the new products, as schematically illustrated in Figure 1. The material consists of re-used material in the form of strips (green, from here on indicated with subscript ‘r’ from ‘re-used’) embedded in a polymer matrix (yellow, from here on indicated with subscript ‘m’). Using classical micromechanical models [3], the stiffness (E-modulus) and the strength of the resulting new composite product (indicated with subscript ‘c’) can be predicted.
The Report • September 2017 • Issue 81 | 53
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