Microstructure and compressive strength of gypsum-bonded composites with papers, paperboards and Tetra Pak recycled materials

Dafni Foti,Geoffrey Daniel,Elias Voulgaridis,Costas Passialis,Stergios Adamopoulos,Eleni Voulgaridou,Stephen Osakue Amiandamhen

doi:10.1186/s10086-019-1821-5

Abstract

The incorporation of recycled papers, paperboards and Tetra Pak as filling materials in brittle matrices presents an interesting approach in the utilization of waste materials for building construction. This paper examines the compressive strength and microstructure of gypsum-bonded wastepaper-based composites. Recycled wastepaper of various types (office paper, magazine paper and newspaper), cardboards, paper boxes and Tetra Pak were shredded to short length strips of about 4 × 18 mm. The shredded materials were used as filling materials in natural gypsum in a ratio of 1:3 (v/v), and water was added to the mix. The paste was formed in cylindrical samples measuring 10 cm in length and 5 cm in diameter. Seven different types of composites were produced depending on the material used. The composite products with newspaper and magazine paper had significantly lower density and compressive strength (p < 0.05) than the others. However, the differences were small to have any practical importance. The density values ranged between 1.26 and 1.34 g/cm3, and compressive strength was the lowest (4.48 N/mm2) in the gypsum–magazine paper composites and the highest (6.46 N/mm2) in the gypsum–Tetra Pak I composites. Since the samples produced in this study exhibited adequate compressive strength, the products could be suitable for such applications as interior walls in building constructions. Scanning electron microscopy (SEM) examination of the fractured surfaces revealed needle-like structures of gypsite crystals surrounding the fibers, which indicates good adhesion between the hydrophobic matrix and lignocellulosic fibers.

Highlights

Lignocellulosic fibers in various products such as office paper, magazine, newspaper, cardboards, paper boxes and Tetra Pak represent a sustainable source of raw material for composite production
Tetra Pak packaging material used for food storage and preservation is composed of about 75% kraft pulp fibers, 20% low-density polyethylene (LDPE) and 5% aluminum foil by mass
Papers, which includes: (a) office paper collected from old files, photocopies, student’s examination tests, corresponding letters, envelopes, etc., (b) newspaper collected from old newspapers, (c) magazine paper collected from old magazines and periodicals, (d) testliner, kraftliner and fluting papers used in corrugated board manufacturing which are available from paper and corrugated board industries as scrap materials

Summary

Introduction

Lignocellulosic fibers in various products such as office paper, magazine, newspaper, cardboards, paper boxes and Tetra Pak represent a sustainable source of raw material for composite production. Tetra Pak packaging material used for food storage and preservation is composed of about 75% kraft pulp fibers, 20% low-density polyethylene (LDPE) and 5% aluminum foil by mass. Because of the extensive use of these materials, huge quantities are disposed over the world as wastes. Foti et al J Wood Sci (2019) 65:42 of fiber-reinforced inorganic composite products [4]. It has been reported that the surface characteristics and chemical composition of fibers have pronounced effects on composite performance [5, 6]. Strong interfacial adhesion between matrices and hydrophilic fibers results in improved physical and mechanical properties

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