Polymer concrete with recycled PET: The influence of the addition of industrial waste on flammability

The civil construction sector has found use for a range of industrial waste products in the form of substitutes that are as effective as standard construction materials but which have the bonus of providing an ecologically sound alternative for materials that would otherwise become an environmental concern. The use of waste materials in cement and polymer composites is a prime example of this practice. While composites with polymer matrices may display excellent mechanical properties, they must also offer superior flammability resistance. The main aim of this study is to develop innovative polymer concrete composites produced with industrial alumina waste, a by-product of the steel industry. The composites used unsaturated ortoftalic polyester as binder, river sand as aggregate and fly ash as filler. Different compositions of flame retardants were tested, one with polishing alumina (residue) and one with commercial grade alumina, and these were used in concentrations of 15%, 30%, 45% and 60% by weight of resin. The properties assessed were mechanical strength, fire propagation and SEM/EDS image analysis and the results underwent statistical analysis to check for their significance. The compositions with the addition of 60% flame retardant waste showed a reduction of 85% in flame propagation times when compared with the samples without the addition of fire retardants and this was accompanied by increased mechanical resistance. No significant difference was found for the two types of flame retardant in terms of flame propagation time.