Optimization of Foams—Polypropylene Fiber-Reinforced Concrete Mixtures Dedicated for 3D Printing

The continued global urbanization of the world is driving the development of the construction industry. In order to protect the environment, intensive research has been carried out in recent years on the development of sustainable materials and ecological construction methods. Scientific research often focuses on developing building materials that are renewable, energy-efficient, and have minimal impact on the environment throughout their life cycle. Therefore, this article presents research results aimed at developing a concrete mixture using cement with reduced CO₂ emissions. In the context of increasing ecological awareness and in line with European Union policy, the development of a mixture based on environmentally friendly cement is of key importance for the future development of the construction industry. The article compares the physical properties of two mixtures, their foaming possibilities, and the influence of the added polypropylene (PP) fibers on the strength properties of the produced composites. It was found that bending strength and compressive strength were highest in the material with silica fume and aluminum powder at 5.36 MPa and 28.76 MPa, respectively. Microscopic analysis revealed significant pore structure differences, with aluminum foamed samples having regular pores and hydrogen peroxide foamed samples having irregular pores. Optimizing aluminum powder and water content improved the materials' strength, crucial for maintaining usability and achieving effective 3D printing. The obtained results are important in the development of research focused on the optimization of 3D printing technology using concrete.