Influence of polyethylene terephthalate microfiber, alkaline activators and other additives on the physical and mechanical properties of concrete

Abstract

The construction industry today is focused on reducing environmental impact and abandoning Portland cement in favor of alternatives such as geopolymer concretes formed by alkaline activation of aluminosilicates. At the same time, the recycling of polyethylene terephthalate (PET) to reduce waste is an acute issue. This article is devoted to the review and systematization of types of alkaline activators in combination with PET fiber made from recycled materials, as well as to the assessment of their influence on the properties of the composite. Sodium hydroxide, sodium silicate and their combination are considered, along with the effect of various fibers and fly ash on concrete strength. It is established that the optimal concentration of sodium hydroxide is 10-12 M, at which alkaline hydrolysis of the PET fiber surface ensures increased adhesion. The introduction of PET fiber raises the flexural strength up to 130,0 kg/cm² and the compressive strength up to 132,40 kg/cm². The use of geopolymer compositions reduces CO₂ emissions by 20-50% compared to traditional concrete. As a result, the most demanded types of activators are identified and their effect on concrete strength is compared.