Introduction. There is a general worldwide aspiration to increase the sustainability in every national economy branch, including road engineering. The growing use of various industrial by-products as economical and eco-friendly road construction and maintenance techniques can be observed in many countries. Coal fly ash is a worldwide available industrial by-product that can be advantageously used in road sector.
Problem Statement. The utilization of various types of fly ash in road sector can be not only en-vironmentally friendly, but also cost effective; however, eventually several special technological measures must be taken.
Purpose. Presenting best practices and development trends for the use of coal fly ash in various road construction and maintenance techniques based on decade-long Hungarian and foreign experiences.
Materials and Methods. The main types investigated here are coal fly ash, eventually with acid or basic modification, also in treated forms, as well as bottom ash. The main utilization areas in road construction and maintenance are asphalt layers (principally the filler of the mixture), cement production, cement concrete pavements, other hydraulically bound pavement layers and subgrade material. (Additionally, the by-product can be used, among others, for bricks and blocks, wastewater treatment, and scrubber sludge solidification).
Results. Presenting best practices for the use of various types of fly ashes in road construction and maintenance can be beneficial for the experts of countries with limited experience in the field. The development directions (trends) outlined in the paper can supply with useful information for every interested road expert all over the world.
