Use of Plastic as a Replacement of Fine Aggregates in Concrete Admixtures

Abstract

Although current legislation established that 35% of plastic waste must be recycled on Puerto Rico (PR), actual figures are far below this target (ADS, 2017). Plastic materials have a great impact on the environment since they have no biodegradable properties (Rodriguez, 2010).

This research studied the feasibility of using type 5 industrially shredded plastic, currently not recycled in PR, as a replacement of fine aggregate in concrete admixtures, in order to provide a recycling alternative that may reduce their disposal. A normal resistance admixture was designed as a control sample, and several admixtures replacing 0% to 30% by volume of fine aggregate were developed. The materials were characterized, the fresh admixture properties were measured, and the samples were cured and tested in compression and tension (split test) at different ages in accordance with the American Society for Testing and Materials (ASTM) Standards.

The results were very promising, and demonstrated that, in terms of capacity, shredded plastic type 5 could be a suitable replacement for a significant part of the fine aggregate in concrete admixtures, since the resistance obtained was similar or better than the control sample. By reducing the disposal of this material, one may contribute not only to the reduction of the impact of the plastic on landfills, but also to the reduction of the impact that plastic carried out from landfills has in the environment, wildlife, and domestic animals; and one may also contribute to the reduction of the extraction of fine aggregates from rivers and borrow pits.