Fortifying concrete by adding recycled plastic
Discarded plastic bottles could one day be used to build stronger and more flexible concrete structures. A research team has found out that the addition of pulverised PET increases the strength of concrete by up to 20 percent.
Concrete production contributes heavily to greenhouse gas emissions, thus a need exists for the development of durable and sustainable concrete with a lower carbon footprint. This can be achieved when cement is partially replaced with another material, such as waste plastic, though normally with a tradeoff in compressive strength.
Harmless doses of gamma radiation
The study discusses progress toward a high/medium strength concrete with a dense, cementitious matrix that contains an irradiated plastic additive, recovering the compressive strength while displacing concrete with waste materials to reduce greenhouse gas generation. Compressive strength tests showed that the addition of high dose (100 kGy) irradiated plastic in multiple concretes resulted in increased compressive strength as compared to samples containing regular, non-irradiated plastic.
Crystalline structure with more crosslinking
This suggests that irradiating plastic at a high dose is a viable potential solution for regaining some of the strength that is lost when plastic is added to cement paste. The investigations revealed that samples containing irradiated plastic – particularly at high doses – exhibited crystalline structures with more crosslinking, or molecular connections. The crystalline structure also seemed to block pores within concrete, making the samples more dense and stronger. By partially replacing Portland cement with a recycled waste plastic, this design may have a potential to contribute to reduced carbon emissions when scaled to the level of mass concrete production.
