Mechanical Characteristics Based on the Microstructure Analysis of Cementitious Composites Incorporating Polypropylene Powder

Incorporating recycled plastics into construction materials offers environmental and economic benefits. This study examined the properties of cementitious composites incorporating recycled polypropylene (PP) powder to evaluate the feasibility of plastics as construction materials. Experimental parameters included PP content and a curing method. Ninety-six specimens were fabricated for compressive strength tests and 48 for flexural strength tests, with six specimens per parameter. The mechanical behavior of the PP cementitious composites was assessed through compressive and flexural strength tests alongside digital image correlation analysis. Field emission scanning electron microscopy (FE-SEM) and mercury intrusion porosimetry (MIP) were used to analyze the pore structure of cementitious composites. Additionally, X-ray diffraction and thermogravimetric analysis examined the thermal and chemical characteristics. Compared with the control specimens, cementitious composites containing 30% PP exhibited approximately 30% reduction in compressive strength but a 28% increase in flexural strength. FE-SEM and MIP results revealed defects that deteriorated the performance of the cementitious composites. However, the compressive strengths exceeded 30 MPa across all the tested parameters, which is satisfactory for construction applications. Furthermore, the addition of PP enhanced flexural strength, providing structural benefits that render it a viable option for sustainable construction materials.