This book highlights a new lightweight composite reinforced concrete section developed with a novel use of a lightweight concrete block as infill utilizing waste plastic. The book's content is also regarded as a solution to the sustainable option to reduce plastic waste. This book first presented the background of plastic and its recycling method. The book then highlights the physical and mechanical properties of different artificial lightweight aggregate and their effect on concrete strength. In the final chapter, the experimental low-impact load tests, and the infill beam development with modified artificial polyethylene aggregates as a full replacement under a certain drop height with an impact weight were described.