STUDY ON THE EFFECT OF MECHANICAL PROPERTIES OF 3D PRINTED CONCRETE WITH PLASTIC WASTE AS AGGREGATE

Abstract

The construction industry is a major contributor to extracting natural resources for the production of concrete in building constructions. As the decades pass, the rise in demand for natural aggregates has caused the exhaustion of such materials at a startling level. This is especially serious in Singapore where there is a heavy dependence on foreign countries for such supply. Apart from sustainability issues, the industry is infamous for its high reliance on manual labour. Many studies have identified that the building and construction industry is very much lacking behind in terms of adopting technology. The unfortunate event of Coronavirus disease (COVID-19) greatly impacted many foreign workers in dormitories, and this has revealed to Singapore that an overdependence on such labour comes with a heavy cost.

In this review, the aim is to counter the issues mentioned above through a partial substitution of sand with fine plastic waste aggregates in the production of 3D printed concrete. Plastic aggregates will be developed by processing waste Polyethylene Terephthalate (PET) bottles. Being non-biodegradable, PET poses a range of serious threats to our environment and health. Several studies have shown that plastic can be adopted in the building industry as it has desirable properties such as inert behavior and resistance to degradation. Consequently, reusing PET waste in concrete production can help to promote better use of these wastes. On the other hand, by utilizing 3D printing technologies, it will greatly reduce the manpower required for a building project.

This dissertation will study the application of PET waste in 3D printed concrete by reviewing the concrete’s mechanical properties. The test results indicate that the addition of PET plastic aggregate will bring about a drop in compressive strength. From the splitting and shear test, PET contributed to a minor reduction in the interlayer bond strength. More significantly, the bending test results demonstrates a considerable enhancement in the intrinsic material strength of the printed concrete with PET aggregates Further research is essential to find the optimal mortar mix and type of PET plastic used, to increase the interlayer bond strength of the printed concrete.