Civil construction consumes large quantities of raw materials and energy, as well as being one of the biggest generators of waste, and is responsible for a significant portion of environmental impacts worldwide. Choosing a more sustainable construction system is essential for the environment, especially in the case of large-scale projects. The aim of this work is to use the waste from the manufacture of concrete blocks, at the time of pressing, to make the micro-concrete to fill the block cavities during the erection of the structural masonry, as specified in the structural calculation project. This work involved characterizing the waste and the aggregates commonly used to make micro-concrete. The mechanical and workability properties of the micro-concrete were assessed using consistency and compressive strength tests. The compressive strength and absorption of concrete blocks filled with microconcrete were also evaluated. The study of replacing sand with waste to make micro-concrete showed results that made this substitution feasible without loss of properties.