The significance of the factors increasing the asphalt pavement recycling rate in the country, determined using multiple-criteria decision-making methods

Abstract

Asphalt pavement, a component of transport infrastructure, deteriorates under the influence of destructive factors. The damages which have occurred during its period of use are repaired and the asphalt pavement is recycled when its further rehabilitation is economically and technically irrational. The material from the asphalt pavement layer that has reached its limit state is milled out or broken and crushed and then is repeatedly used in the production of hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures. In this paper, the dynamics of the percentage recycling ratio (RR) of old asphalt pavement material was investigated. RR represents the quantity of reclaimed asphalt pavement (RAP) used in the production of HMA and WMA mixtures in Europe and the USA, divided by the total amount of RAP prepared in the country. Factors and goals affecting it are analyzed. An original system of 10 criteria that increase the RR country has been created. Decision makers do not know which factors have the maximum influence in increasing the use of RAP and this should go in connection with environmental pollution reduction and achieving economic utility. By applying different multiple-criteria decision-making (MCDM) methods and using the importance given to these criteria by 14 experts, the normalized subjective weights of the criteria were determined. Analytic hierarchy process (AHP), rank correlation, average rank transformation into weight—linear (ARTIW-L) and non-linear (ARTIW-N), and direct percentage weight (DPW) methods were used in the study. The results show that the RAP recycle rate is close to 100% in countries with a sustainable economic background. In the Baltic countries, it is mostly increased by the adequacy of regulatory documents, the strategy promoting asphalt recycling in the country, and the homogeneity and classifying of RAP. The number and capacity of RAP stocks, the number and productivity of asphalt milling equipment and the wear and tear of the asphalt pavement have the least influence on the increase in RR. The opinions of experts in assessing the significance of all criteria are consistent. The averages of the weights of criteria determined by four MCDM methods (AHP, ARTIW-L, ARTIW-N, DPW) made it possible to obtain more reliable results. These results can be used to make strategic decisions and to create a plan of practical actions to increase the RAP recycling rate in the developing countries.