Valorization of EVA waste from footwear industry as natural aggregates substitutes in mortar: the effect of granulometry

The increased consumption of polymers and the consequent generation of waste requires the development of efficient recycling strategies. In this paper, poly(Ethylene–Vinyl Acetate) (EVA) waste with millimetric (1–3.15 mm) and micrometric (< 562 µm) granulometries were compared as lightweight aggregates substitutes for mortar. Additionally, millimetric EVA was coated with natural aggregates through a thermal treatment before mortar incorporation. The volumetric content of replaced natural aggregates in mortars ranged from 0 to 70%. It was concluded that the mortar density decreases with EVA incorporation, the stronger effect being obtained with millimetric EVA (22% vs 18%, for millimetric and micrometric EVA, 50% EVA). The flexural and compressive strengths decreased with increasing polymer replacement, although flexural strength was less affected than compressive strength and micrometric EVA proved to be less detrimental to the mechanical properties than millimetric EVA (50% vs 37% for flexural strength and 71% vs 64% for compressive strength for millimetric and micrometric EVA, 50% EVA). The water sorptivity coefficient substantially decreased with the addition of micrometric EVA. The less affected mechanical properties and better waterproofness achieved with the addition of micrometric EVA waste to mortar opens the possibility to obtain better quality polymer-substituted mortars with possible application in plasters or masonry laying.