As the railway lifespan is the main criterion for selection of the aggregate for ballast and for planning the maintenance of the railroad, it is important to define the relationship between the particle load resistant characteristics and a lifetime of ballast in structure. Assessment of the quality of the ballast aggregate particles under dynamic and static loading reflect both, the toughness and hardness, and these are identified with the Los Angeles Abrasion and Micro-Deval Abrasion values. The model formerly developed by Canadian Pacific Railroads was adapted to predict possible loads expressed in cumulated tonnes. Different ballast aggregate mixtures were tested in the laboratory including dolomite and granite. Calculated potential gross tonnage (expressed in Million Gross Tonnes) of the railway per lifetime for each different aggregate type presented. The outcome of this research is established classification system of railway ballast aggregate and defined Los Angeles Abrasion and Micro-Deval Abrasion values of aggregate dependently on required lifetime.

The increased use of geosynthetics in road constructions has resulted in a need to better understanding of geosynthetics properties for the use in design and quality control. For this purpose, the regulations for use of geosynthetics for road embankments and subgrades were created in Lithuania. It was found that other European countries such as Germany and United Kingdom use not only harmonised European standards, but also has their own regulations for geosynthetics. This study indicates the relationship between regulations in Lithuania and other countries. Calculation conception and regulations for controlling characteristics were introduced first time in Lithuanian road construction market. The use of those regulations will increase the quality of construction and life time of road pavement structures.

Geosynthetic materials are more and more often used for subgrade reinforcement and/or stabilisation. Geosynthetic reinforcement products used for paved and unpaved roads or traffic areas function on the basis of two mechanisms that contribute to their performance. Shear loads developing in unbound granular layers as a result of traffic loading are transmitted from the base aggregate to the geosynthetic as a result of frictional interaction or via the so called interlocking effect. Depending on the geosynthetic material properties load absorption functions on the basis of frictional interaction and the membrane effect. This study indicates how these two load absorbing mechanisms, depending on the geosynthetic material properties, correspond to the regulations for use of geosynthetics for road embankments and subgrades and harmonised European standards that are valid in Lithuania. It also presents the corrections and additions to improve the existing regulations for use of geosynthetics for road embankments and subgrades to ensure a better paved road durability.

Many roads with asphalt pavement are being reconstructed every year, as their quality becomes insufficient by the requirements. As it is well- known, old roads were built not in the very best quality, so doing reconstruction projects in the most cases there were required to deal with soft soils that are under the existing road structure. Geogrid reinforcement was widely used to solve issues of soft soil in Lithuania. There are projects where geogrid reinforcement is used to control road pavement roughness when there are layers of peat or silt under road structure instead of using concrete piles or geosynthetic-encased soil columns. This type of geogrid reinforcement application is unexplained in any normative-technical document but widely used in Lithuania. This application was usually made constructively without any calculations, choosing the reinforced solution by reducing the geogrid tensile strength or layer quantity compared to reinforced load transfer platform over piles. This paper evaluates the long-term influence of geogrid- reinforced subgrade on the roughness of asphalt surfacing and bearing capacity of the road structure when the soft peaty soils stratify in the deeper layers of the subgrade. There were compared the reinforced sections to adjacent sections to see the effect and fortunately a large number of adjacent sections were also strengthened, mostly by lime stabilisation. Therefore, this comparison allows making more insights on the long-term performance of the strengthened subgrade and influence on the road quality. This research gives recommendations on how the geogrids has to be selected to be used in this kind of application.

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