Concrete is one of the most popular construction materials in the world. The concrete properties depend from many factors. One of them is aggregates quality, which can be defined as an impurity level. The most unwanted materials in fine aggregates are clay and soil particles. These particles can impure aggregates due to irregular sands in quarry and during the digging process. In the present paper were estimated how impurity impact the properties of concrete. During the research the aggregates were impured with clay and soil particles. The change of fresh concrete workability, hardened concrete density, compression strength, water absorbability and frost resistance were evaluated. The results show that aggregates impurity with clay and especially with organic materials (soil) is very dangerous. The concrete workability, frost resistance is decreasing. The clay and soil have a different effect on hardened concrete density and compression strength. Soil decreased both parameters while well mixed clay increased these characteristics. However, generalizing all results, can be stated, that keeping the same level of concrete workability it is necessary to raise water and cement ratio and it will give strength loss effect.