High strength concrete for the production of concrete railway sleepers was designed more than 20 years ago.The compressive strength of the concrete was very high from the start, but flexure strengths showed some irregular development-a decrease in time.Later, also a significant decrease of fracture properties was recorded.Microcracking was found to be the reason for this;therefore some modifications were performed to avoid this happening (especially the reduction of the maximum size of aggregates from 22 mm to 16 mm or 11 mm).Some problems concerning frost resistance of the concrete with a slag addition were reduced by applying ternary binders.All of the results are discussed from the point of view of a long-term observation of the strengths and fracture properties development during the time period of 5 years or even more.