Recycling of crushed clay brick and roof tile is an environmentally friendly way of their disposal. During the production and transport a part of produced bricks and roof tiles becomes broken in the factory and it is crushed straight away in the factory. One way to reuse crushed bricks and roof tiles is through their usage as recycled aggregate for concrete. Since the application of concrete with crushed clay bricks and roof tiles is not widespread, it is necessary to investigate the possibility of applying it in areas where such concrete shows better properties than concrete with natural aggregate. Based on literature review, concrete with crushed clay bricks and roof tiles has better thermal properties and fire resistance than ordinary concrete with natural aggregate. In dissertation is investigated the possibility of usage of crushed bricks and roof tiles in the fire resistant precast concrete roof blocks. The review of the current areas of application of concrete with crushed bricks and roof tiles as aggregate, objectives and possible constraints related to researching the usage of crushed bricks and roof tiles in new construction applications are shown. The requirements to be met in order to ensure the application of crushed clay bricks and roof tiles as concrete aggregate in new precast concrete block and beam floor systems are shown. Experimental investigations have a significant role in the area of innovative application of existing materials, improvement and development of their production process. Set goal of experimental investigation could be very complicated because of great number of variables that could have a significant impact on the results of experiment. Therefore, in dissertation is chosen a plan of experiment that comprises the most important variables, and in this way the extent of research is decreased without a risk of significant reduction of result accuracy. A preliminary experimental testing of properties of concrete components was carried out, as well as the testing of the concrete with crushed clay brick and roof tiles. Design of experiment applied to testing has been described. Selection of acceptable mixtures was carried out using experimental results and mathematical model. Selection of optimal mixture was carried out using multi-criteria optimization. Selected optimal mixtures were tested at the level of material in terms of physical-mechanical and durability properties after exposure to temperatures of 20° C, 200° C, 600° C, 800° and 1000° C. Based on the results of experimental investigation optimal mixture with the best properties in fresh and hardened state is selected with a view to the possible application in the precast concrete blocks. Experimental tests were conducted on optimal mixture at the level of structural elements – precast concrete blocks. Precast concrete blocks were made of concrete with crushed clay bricks and roof tiles. Their properties were tested at room temperature and after exposure to high temperature, in accordance with requirements of HRN EN 15037-2:2009: Precast concrete products – Beam and block floor systems – Part 2: Concrete blocks. Ultimate limit state verification of blocks was carried out before and after exposure to high temperatures. It was concluded that it is possible to produce precast concrete blocks made of concrete with crushed bricks and roof tiles as aggregate that are applicable for precast concrete block and beam roof/floor systems with improved resistance to high temperature.