Reuse and valorisation of hemp fibres and rice husk particles for fire resistant fibreboards and particleboards

The present manuscript deals with the reuse and valorisation of agricultural wastes and by-products (namely, hemp fibres and rice husk particles) to produce fire retardant fibreboards and particleboards for applications in biobuilding. Since fire retardancy is one of the most important challenges, a detailed study on the thermal and flame retardant properties of the above materials assembled using starch as the binder and different ammonium dihydrogen phosphate contents as fire retardant agents, is proposed. The combustion properties have been investigated in developing fire conditions, employing a radiating heat flux of 35 kW/m2 generated by a cone calorimeter. An optimised formulation able to make both fibreboards and particleboards not ignitable has been found and is predicted to be “A2/B” class in the European fire classification for building products. The resultant materials have proven to undergo pyrolysis and not to burn, favouring the formation of a dense and consistent final residue.