To make concretes lighter, air is introduced into the otherwise closed system. This is done for concretes in accordance with DIN EN 206-1 by using lightweight aggregate with an aggregate density ≤ 2.0 g/cm³. The aggregate is replaced volumetrically by lightweight aggregates such as perlite, expanded glass or expanded clay. This reduces the density from around 2300 kg/m³ to 2000 kg/m³. As the cement paste matrix is retained and these concretes therefore have a high load-bearing capacity, they are also known as structural lightweight concrete. Lightweight structural concretes are regulated according to DIN EN 206-1 up to a cylindrical compressive strength of 80 N/mm². From a cylindrical compressive strength of 60 N/mm², the concretes are defined in the standard as high-strength structural lightweight concretes. Therefore, from a compressive strength of 100 N/mm², it is possible to speak of ultra-high performance lightweight concrete. The special concrete developed here on the basis of UHPC can be defined as a new material class due to its low density and high strength. With the approach of transferring the concept of a structural lightweight concrete according to the standard to an ultra-high performance concrete (UHPC), compressive strengths of over 130 N/mm² at a density of less than 2000 kg/m3 have already been successfully achieved. The aim of this project is now to investigate the durability properties of this concrete and thus enable it to be used on the market. The focus is on freeze-thaw resistance, chloride penetration depth, chemical and mechanical resistance. Furthermore, the design-relevant properties, in addition to the compressive strength, are to be investigated. The load-bearing and deformation behavior of lightweight concretes is influenced by the modification of the microstructure. Crack development and crack interlocking in particular are altered by the lightweight aggregate and ensure low load-bearing behavior. This is to be investigated as part of this project for the design-relevant variables, compressive and flexural tensile strength.