This final seeks to address the impact of mineral admixtures on the properties of concrete such as silicon dust and fly ash including recent research dealing with the application of wood biomass ash and ash generated by incineration of sludge from wastewater treatment. The mineral additives that are treated in this final are created as a by-product in various processes, which means that we don´t use energy for their formation, but we have a problem with their storage and disposal. Today, there are increasing demands for renewable energy, and increasingly strict restrictions on greenhouse gas emissions, which is why we want to further increase the practice of using by-products. Very small particles of ash can easily be carried by the wind, and person can inhale them, which can result in respiratory problems. It is necessary to find an environmentally friendly solution and eliminate the possibility of negative impact on human life. Reducing the negative impact of by-products is trying to achieve by applying it in construction, more precisely in the concrete industry. The first few chapters deal with the main components of concrete and those are aggregate, cement and water, and then with mineral admixtures. Silicon dust and fly ash from coal combustion are already well-know by-products from large plants that have found their application due to their good pozzolanic properties. The addition of silicon dust will increase the 28-day compressive strength, while the addition of fly ash will reduce the heat of hydration and the volume of air trapped in the concrete. Recent research will try to find a way to apply biomass ash and sludge incineration ash.