# Asphal Road Pavements to Address Climate Change Challenges--An Overview
## 1 Introduction  
Asphalt road pavements are exposed to the natural environment. The behaviour of bitumen drives the performance of asphalt road pavements. bitumen is a complex material, exhibiting different behaviours depending on the temperature range. At high temperatures, its behaviour is similar to a Newtonian fluid; at intermediate temperatures, it is similar to a viscoelastic liquid; and at low temperatures, it is similar to a viscoelastic solid [1]. Therefore, climate change challenges will inevitably affect pavement service life. Putting (permanent deformation) performance is the criterion failure most affected [2]. In a study by [PERSON] et al. about climate change for USA conditions, fatigue increased by 2-9% and rutting by 9-40% at the end of 20 years [3]. Current pavement design methodologies assume that climate conditions are stable over the design period [4], which is not valid. Climate change makes weather patterns less predictable [5]. [PERSON], the Secretary-General of the World Meteorological Organization, said, \"_the negative trend in climate will continue at least until the 2060s, independent of our success in climate mitigation_\" [5]. Besides global average surface temperature increase, climate change challenges include droughs, heavy rain and flooding, sea-level rise, coastal floods, and forest fires. The impact of those challenges on asphalt pavement depends on the nature and scale of the climate change challenge. They can range from minor effects, such as travel speed reduction, to infrastructure closure or even infrastructure destruction. A transport network is an essential infrastructure that supports social and economic activities and, thus, must be operational at all times. The United Nations Sustainable Development Goals explicitly included the accessibility and availability of transport networks (SDG 9.1) [6]. The transport system's weather-related disruption entails high direct andindirect costs [7; 8]. Climate change significantly impacts the pavement's life cycle cost (LCC) analysis. [PERSON], [PERSON], [PERSON] and [PERSON] [8] estimated the pavement LCC for 24 climate locations across the United States, concluding that climate change (per \({}^{\circ}\)C) increases agency costs by approximately 650-700 million USD/year. Several studies and projects have been developed to recognise, adapt, and mitigate climate change [9; 10]. However, uncertainty linked to climate change challenges is difficult to anticipate. [PERSON] and [PERSON] [9] developed flood risk curves, which can assess the expected loss, manage risk, and design risk mitigation strategies. Other researchers use models to predict climate change [2; 10]. The most used are based on the Representative Concentration Pathways (RCPs) developed for the 5 th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) [11]. It is a matter of great importance that will likely be exacerbated by continuing urbanisation. In 2018, 55% of the world's population lived in cities, and the United Nations estimates that this percentage will rise to 68% by 2050 [12]. These circumstances can replace permeable lands with impervious surfaces, which causes complex drainage and difficult heat dissipation. It could raise pavement temperature and increase the effects of the floods. Transportation engineers and practitioners should be aware of the impact of climate change challenges on asphalt road pavements and know the main playing variables and available solutions. Although several studies address this topic, most address an issue or develop a pavement solution. This paper aims to present an overview of the climate change challenges with a more significant impact on the performance and serviceability of asphalt mixtures, namely the air temperature and the factors that alter the moisture balance of the asphalt mixture and which, consequently, could influence pavement deterioration (rainfall, flooding, sea-level rise). Moreover, it intends to present pavement solutions to address climate change challenges.