Improvement of functional designation of low-volume roads by dust abatement in Lithuania

Abstract

Gravel pavement prevails in Lithuanian state roads of regional significance, which make up 69% of the total road network. Dustiness of gravel roads reduces visibility and hinders traffic safety. Natural gravel from deposits, the particle size distribution of which ranges widely, is used in most gravel pavement. The variation of the particle size distribution is typical of all gravel deposits of melting glacial waters and those of river genetic origin in Lithuania. Gravel deposits contain a small quantity of fine particles, and the quantity of large particles is sufficient. However, gravel becomes finer because of pavement wear, and the quantity of particles larger than 5 or 4 mm according to standard sieves reduces to between 24.6% and 37%. Fine particle content (fraction <0.06 mm) usually does not exceed 6%. This paper presents research into dust reduction on gravel roads through the use of bitumen emulsions, calcium chloride, and calcium lignosulfonate. It provides recommendations on the concentration of the materials to be used for dust reduction as well as their statistical characteristics. Issues related to the use of materials for dust reduction are discussed. To resolve these issues, a 2 X 2 experimental design was used in the analysis of absorbents. Mathematical modeling was used to define the effectiveness of calcium chloride and calcium lignosulfonate. Recommendations are made with regard to the use of these absorbents in applying the models. The necessity of using cationic emulsions is based on research into dust mineral composition. It is recommended that the estimate of the quantity of materials required for dust reduction take into account the material particles' surface area.