In the last few years a growing environmental awareness in the field of construction materials can be observed. This has been, and continues to be, exacerbated since the Construction Products Regulations entered into force in 2013. In general construction products are in direct contact with the surrounding environment such as groundwater and soil. Especially grouting materials that often contain significant amounts of organic/chemical admixtures are used to modify the properties of the ground or to fill voids in order to seal the ground against moisture and water ingress. A broad variety of such grouting materials that can be used for different applications is available on the market. Due to the direct contact with soil and/or groundwater inorganic and organic constituents may be leached and released into the environment. This work reports about leaching behaviour and mechanisms of three different grouting materials, namely polyurethane, cement and a cement-polyurethane hybrid material. Cement paste and mortar samples were prepared with different superplasticisers, either polycarboxylate ether or a mixture of melamine and naphthalene sulphate condensate. In addition the water-to-cement ratio, pre-storage time and the type of eluent were varied. In case of the polyurethane material the behaviour of three different catalysts was investigated as well as different dosages thereof. Different fractions of cement were replaced by ground granulated blast-furnace slag in case of the cement-polyurethane hybrid material to simulate commonly used slag cements. Leaching was performed with the tank leaching test and the batch test. In case of the polyurethane and cement-polyurethane hybrid material the leaching tests were adopted to gain more information about the leaching behaviour whilst curing. The gained eluates were analysed for general parameters (pH-value and electric conductivity) as well as inorganic constituents (Al3+, Ca2+, Cl–, SO2– 4 , Na+ and K+) via IC and ICP-AES. Organic constituents have been analysed as sum parameter (TOC and/or DOC) and wherever possible as single parameter via liquid chromatographic methods or UV-Vis spectrometry. To study their environmental impact the eluates were analysed with different aquatic and terrestrial ecotoxicological assays. The results showed that the aggressiveness (pH-value and the electrical conductivity) of the eluent plays a key role in leaching. The pH-value of the polyurethane systems stayed constant at pH 7, while for the cementitious systems the pH stays constantly at high values around 12. In general, the leached inorganic ions decrease rapidly over time in case of polyurethane systems. For cementitious systems Ca2+ is leached constantly. In addition K+ and Na+ were identified as counterion of the superplasticiser. The TOC of all samples is constantly decreasing within the first few leaching steps. The main leaching mechanism for the total organic carbon was identified as wash-off effect for all the samples. It was also possible to detect superplasticiser traces in the cement leachates with HPLC-MS or UV-Vis spectrometry. Statistical data analysis of the ecotoxicological assays showed that time is a significant factor controlling the leaching process. The superplasticiser dosages play a subordinate role in the cementitious systems while the catalyst dosage is a significant factor for the polyurethane systems. With this thesis an insight is given in the complex topic of leaching of building materials and their environmental impact. However, further research needs to be done to gain better and in-depth understanding of the leaching process and the interaction of the leachates with the environment.