A multi-site study of a new cement composite brick with partial cement substitutes and waste materials

The building industry is a major contributor to climate change since it emits massive amounts of greenhouse gases. As a result of this research, a cement composite brick with partial cement substitutes and waste material was developed. The fresh formula mixture and hardened concrete were tested for physical, mechanical, and thermal properties to ensure that the assumptions were true. In this study the role of zaolite, metakaolinite and micrometakaolinite at different proportions, i.e. 5%, 10%, and 15% as well as recycled fibers (glass, polypropylene and steel) at 0.5%, 1.0% and 1.5% dosage in the production of cement composites was researched. 20 recipes in total have been tested until achieving the final recipe of the mentioned brick. The main purpose of this research was to develop the concrete mixture that will be used to produce cement bricks with increased physical, mechanical and thermal parameters. The compressive strength of the brick developed with the modified formula increased by 22% compared to the reference sample. Also, higher mechanical values were obtained for the splitting strength and flexural strength, which increased by 14% and 32%, respectively, compared to plain concrete. Based on the thermal test results it was developed that zeolite, metakaolinite and micrometakaolinte have no effect on thermal properties of concrete. Only after incorporating fibers into mixture, those properties changed. Also, the SEM images showed an even distribution of the fibers in the composite matrix and a crack-free structure. Moreover, the image analysis results confirmed the failure character consistent with traditional concretes in the case of compression and the lack of split into two independent samples in the case of bending. Therefore, the new composite brick has great potential to be used as a primary replacement for traditional concrete masonry in civil engineering projects.