The production of concrete has experienced significant growth worldwide. Concrete is a key material in the construction industry and is used in the construction of various structures, from residential and commercial buildings to infrastructure projects such as bridges, roads, and tunnels. However, this increase in concrete production has negative environmental consequences. The production of concrete and cement requires large quantities of natural resources such as sand, gravel, and limestone. Excessive exploitation of these resources can have serious environmental consequences, including coastal erosion, habitat degradation, and potential resource depletion. To reduce the excessive use of natural resources and mitigate the negative impact of concrete production on the environment, there is a growing demand for alternative materials. Alternative materials are becoming increasingly popular because they can include waste materials, solving the problem of their disposal, such as the commonly used recycled aggregate obtained by crushing construction waste. Given these facts, the basic idea of this thesis is to use waste material generated in the concrete production process. This thesis examines cement waste sludge generated in settling tanks after separation from wastewater in facilities that deal with the preparation of concrete and cement mixtures. The experimental part of the study was based on the preparation of custom cement mortar mixes in which cement was replaced with cement waste sludge in amounts of 0%, 5%, 10%, and 15% by weight of cement. The results of testing mixes with different proportions of cement waste were compared to a reference mix. The goal is to obtain a cement mixture with a certain proportion of cement waste sludge that still meets the strength requirements specified by the standard for cement used in the preparation of the reference mix. A loss of workability of the mixes was observed as the proportion of cement waste sludge increased. Standard cement strength tests were conducted on hardened cement mortar samples, including compressive strength testing and flexural strength testing. All hardened cement mortar mixtures were tested at 3 days and 28 days of age. As with standard mortar samples, samples at a greater age achieved higher strength, suggesting that certain curing processes occur within that time frame. The test results show that the compressive and flexural strength of the material decreases with increasing amounts of cement waste sludge in the mixture.