Effects of natural fibres reinforcement in lime plasters (kenaf and sisal vs. Polypropylene)

• Mechanical and durability properties of several lime plasters were studied.
• Effect of synthetic or natural fibres was investigated.
• The use of natural fibres is functional to the reduction of tensions.
• The sisal and kenaf fibres can be a valid alternative to polymeric ones.

Nowadays the tendency to realize environment-friendly products is becoming more widespread to ensure sustainable and smart development.The synthetic fibres, frequently used, are harmful to the environment because they are non-degradable and non-renewable. Their use has resulted in an increase of oil consumption. Therefore, the possibility of replacing them with natural fibres becomes increasingly concrete confirmed by the researches and investigations carried out.In this work three lime based plasters were prepared and analysed to evaluate the influence on their performance of different fibres used as reinforcement. In particular each plaster was realised by adding to the mortar the same amount (i.e. 0.2% w) of polypropylene, sisal (Agave sisalana) and kenaf (Hibiscus cannabinus) fibres, respectively. Then, compressive and bending strength, resistance to freeze/thaw conditions and to marine environment (by performing salt spray test) of lime plasters were investigated.On the basis of experimental results, natural fibres can be considered as a valid alternative to polypropylene ones as reinforcement of lime plasters. In particular, the decrease of mechanical properties due to freeze/thaw cycles is comparable under flexural load condition for all plasters analysed in this work, while the decrease of compressive strength, shown by plasters reinforced with sisal fibres, is lower than other ones. Moreover, thanks to their higher hydrophilicity, the plasters reinforced with natural fibres present low weight loss after ageing time in salt spray environment than ones with polypropylene.