A chemical, morphological and mineralogical study on the interaction between hemp hurds and aerial and natural hydraulic lime particles: Implications for mortar manufacturing

Mixing hemp with aerial or natural hydraulic lime gives rise to mortars with improved flexibility and insulation but with peculiar microstructure compared to lime-aggregate mortars. The chemical-mineralogical and morphological investigation carried out here shows that hemp absorbs most of the water present in the matrix, causing superficial deposition and scarce adhesion of the lime to the hemp. This also delays the hardening process, as demonstrated by the high content of portlandite, vaterite and calcium silicates found after three months of curing. Some modifications to the production and curing procedures are suggested to improve the microstructure and final performance of hemp-lime mortars.