# Hybrid Mortar Composites Incorporating Oyster Shell Filler and Recycled Fibers from Disposable Masks

## TL;DR

This paper explores using waste materials from face masks and oyster shells to create stronger, more sustainable mortar composites.

## Contribution

The novel contribution is combining oyster shell powder and recycled mask fibers to enhance mortar properties while repurposing waste.

## Key findings

- Adding 5% oyster shell powder increased compressive strength by 10% and bond strength by 21%.
- An optimal 0.2% of 6 mm mask fibers maintained tensile strength similar to the control mix.
- Higher fiber content or longer strips reduced strength due to increased porosity and water absorption.

## Abstract

This study presents the development of hybrid masonry mortars by incorporating two waste materials: recycled plastic strips from disposable face masks (FM) as mechanical reinforcement and calcined oyster shell powder (OSP) as a filler. The objective was to evaluate the combined effect of FM and OSP on the mechanical behavior of mortars. Three types of mixes were prepared: a reference mix, a mix with 5% OSP (by cement weight), and mixes with 5% OSP reinforced with FM strips. FM strips were incorporated at three different lengths, dividing the FM-reinforced group into three subgroups (0.1%, 0.2%, 0.5%, and 0.8%). The results showed an approximately 10% increase in compressive strength with the addition of 5% OSP compared to the control mortar, as well as an improvement in bond strength of about 21%. Furthermore, an optimum content of 0.2% of 6 mm strips allowed for adequate dispersion and maintained indirect tensile strengths similar to the control + OSP. OSP acted as a reactive filler, increasing compressive strength and improving both density and adhesion. However, higher FM contents or longer strips increased porosity and water absorption, while reducing strength. This combination represents an innovative strategy for valorizing post-pandemic and marine waste.