Durability Characteristics of Polypropylene Fiber–Reinforced Waste Cardboard Concrete

Abstract

This paper presents an experimental study and its findings on the durability characteristics of fiber-reinforced cardboard concrete. The requalification of recycled waste in construction and building materials has become significant in the last decade, leading to the promotion of viable recyclable products for the construction industry. This study focused on the use of cardboard, polypropylene, and fly-ash in the characterization of a structural-grade concrete and extended upon the findings of a precursor study in the development of an eco-efficient cardboard concrete mixture. Finely processed municipally collected waste cardboard and recycled polypropylene macrofibers were incorporated into a concrete mixture design for which an experimental program was achieved to determine the apparent volume of permeable voids, electrical resistivity, thermal conductivity, carbonation resistivity, immersed absorption, creep, drying shrinkage, and ultrasonic pulse velocities. The results show a decrease in thermal conductivity and an increase in specific heat by 25% and 32%, respectively, underscoring significant insulative properties. Bulk electrical conductivity testing was shown to decrease by 43% but improve upon previous findings on resistance to chloride ion ingress. Creep and drying shrinkage testing showed a 54% increase in creep strains and a 42% increase drying shrinkage strains. Porosity testing determined a 50% increase in permeable voids, with the rate reducing to 42% for a longer curing period. Durability properties for the cardboard concrete were found to be in the appropriate range for structural-grade concrete and underscored the suitability of waste cardboard in concrete mixtures.