Recycled cement mortars reinforced with PVDF nanofibers synthesized by electrospinning

Abstract

Due to the significant environmental problems caused by obtaining raw materials for construction, it has become very important to replace natural fine aggregates with recycled fine aggregates (RFAs) in the production of cementitious materials. However, the use of RFAs decreases the mechanical properties of cementitious materials. The addition of nanofibers (NFs) is a promising way to counteract this disadvantage. In our study, polyvinylidene fluoride (PVDF) NFs were synthesized by electrospinning and added to mortar mixtures in proportions of 0.025, 0.05, and 0.1 % by weight of cement in order to evaluate their effect on the microstructure, flowability, compressive strength, flexural strength, total porosity, and resistance to chloride-ion (Cl−) penetration of those mortars. The results showed that the PVDF NFs had diameters of 788 nm and they physically interacted with the hydration products. In terms of compressive and flexural strength, the addition of 0.1 % NFs caused an increase of 12 and 23 % respectively, and a decrease in porosity of 3 % in relation to recycled mortar. In addition, the recycled mortars with NFs saw a 20 % increase in chloride-ion permeability, which could help to broaden the applications of recycled mortar. The PVDF NFs in recycled mortars counteract the negative effects of using RFAs, in addition to improving cementitious materials.