Alternative uses for crushed stone products generated to meet the raw material needs of asphalt production in Hungary

Abstract

In Hungary, quarries that produce stone products for wearing courses of asphalt pavements also produce a significant amount of 0/4, 0/8 and 4/8 mm fractions. Because of Hungary’s pavement design and asphalt production practices, these fractions do not have a suitable market and can thus be sold on alternative markets. Purpose. To demonstrate the feasibility of using crushed fractions of 0/4 and 0/8 mm in the protection and base layers of asphalt pavements instead of sandy gravel with 0/22 mm fraction. Methodology. The CBR method was applied to evaluate the comparability of characteristics such as particle size distribution and load-bearing capacity. The combination of the Proctor and CBR tests allowed someone to compare the expected technological characteristics of the dominant and alternative aggregate types, such as their sensitivity to water and load-bearing capacity. Findings. The results demonstrated that the performance characteristics of conventionally used sandy gravel with a size of 0/22 mm can be achieved and exceeded by crushed material with much smaller maximum grain sizes – i.e., 0/4 and 0/8 mm. Originality. The paper presents an original study that contradicts the industry’s actual decline of crushed stone (0/4 and 0/8 mm fractions) for asphalt pavement protection layers. The potential effectiveness and functionality of the proposed coating are demonstrated through convincing tests, and thus new data and insights are introduced into the Hungarian construction industry’s practice. Practical value. The test results greatly helped in achieving the high demands of the private industrial project by proposing an alternative variant of crushed stone of 0/8 mm fraction rather than the originally planned dominant sand and gravel material. The asphalt paving experience on this site clearly demonstrated the viability of the alternative aggregate option for Hungarian roads.