Experimental study on polyester based concretes filled with glass fibre reinforced plastic recyclates – a contribution to composite materials sustainability

摘要

The development and applications of thermosetpolymeric composites, namely fibre reinforced plastics(FRP), have shifted in the last decades more and moreinto the mass market [1]. Despite of all advantagesassociated to FRP based products, the increasingproduction and consume also lead to an increasingamount of FRP wastes, either end-of-lifecycleproducts, or scrap and by-products generated by themanufacturing process itself. Whereas thermoplasticFRPs can be easily recycled, by remelting andremoulding, recyclability of thermosetting FRPsconstitutes a more difficult task due to cross-linkednature of resin matrix. To date, most of the thermosetbased FRP waste is being incinerated or landfilled,leading to negative environmental impacts andsupplementary added costs to FRP producers andsuppliers. This actual framework is putting increasingpressure on the industry to address the optionsavailable for FRP waste management, being animportant driver for applied research undertaken costefficient recycling methods. [1-2]. In spite of this,research on recycling solutions for thermosetcomposites is still at an elementary stage. Thermaland/or chemical recycling processes, with partial fibrerecovering, have been investigated mostly for carbonfibre reinforced plastics (CFRP) due to inherent valueof carbon fibre reinforcement; whereas for glass fibrereinforced plastics (GFRP), mechanical recycling, bymeans of milling and grinding processes, has beenconsidered a more viable recycling method [1-2].Though, at the moment, few solutions in the reuse ofmechanically-recycled GFRP composites into valueaddedproducts are being explored.Aiming filling this gap, in this study, a new wastemanagement solution for thermoset GFRP basedproducts was assessed. The mechanical recyclingapproach, with reduction of GFRP waste to powderedand fibrous materials was applied, and the potentialadded value of obtained recyclates was experimentallyinvestigated as raw material for polyester basedmortars. The use of a cementless concrete as hostmaterial for GFRP recyclates, instead of aconventional Portland cement based concrete, presentsan important asset in avoiding the eventualincompatibility problems arisen from alkalis silicareaction between glass fibres and cementious bindermatrix. Additionally, due to hermetic nature of resinbinder, polymer based concretes present greater abilityfor incorporating recycled waste products [3].Under this scope, different GFRP waste admixedpolymer mortar (PM) formulations were analyzedvarying the size grading and content of GFRP powderand fibre mix waste. Added value of potentialrecycling solution was assessed by means of flexuraland compressive loading capacities of modifiedmortars with regard to waste-free polymer mortars.