A multiscale model for pervious lime-cement mortar with perlite and cellulose fibers

•Pervious lime-cement mortar (PLCM) with perlite and cellulose fibers was characterized.•A three-phase macrostructural model and a multiphase paste microstructure described.•The multiscale model considered mortar voids and paste porosity.•Active void size and paste thickness were related to PLCM performance parameters.•Perlite and cellulose fibers modified both paste thickness and active void size. A pervious lime-cement mortar (PLCM) with perlite (P) and cellulose fibers (FC) was studied for better understanding the relationships among mortar composition, microstructure and properties, especially thermal and acoustic performance. Mortar microstructure was studied by optical and scanning electron microscopy, water absorption and nitrogen adsorption/desorption tests. A multiscale model for PLCM with and without P and/or FC was proposed: a three-phase macrostructural model consisting on a gap-graded aggregate, a paste shell and a continuous void network; paste phase was described as a multiphase microstructure. Paste thickness and active void size were identified as PLCM macrostructural parameters. The use of P and FC widened the paste shell, reducing the active void size. While the effect of P depends on particle size rather than the proportion used, the effect of FC depended on fiber amount. The model could be useful for optimizing the design of PLCM and predicting thermal and acoustic performance.