# Life Cycle Assessment of Concrete Pavement Rehabilitation: A Romanian Case Study
## 2 Short History  
The concept of life cycle analysis first appeared in the 1960s, due to the rapid depletion of fossil fuels, which caused widespread global interest in energy, and it was first used to understand and assess the impact of energy consumption [24]. Big industrial companies in the USA [25] were the initiators of the concept of the life cycle analysis. Its development has focused on the systematic approach used to assess the environmental consequences of a product, process, or activity from a cradle-to-grave perspective. Initially, researchers focused on the energy consumption of existing buildings, capitalizing on their energy-saving potential. Subsequently, it gradually expanded to all aspects of infrastructure construction. Research on road energy consumption also appeared relatively early on, and many research achievements have been applied in practice. Figure 2: LCA classification [1]. Over time, studies have been conducted in the field of road infrastructure; more precisely, among the first studies on the life cycle analysis of a pavement structure were done in Finland in 1960 by [PERSON] and [PERSON] [5; 26; 27]. The study consisted of a comparative analysis between ordinary concrete pavements and asphalt pavements. The authors conclude that when the energy of the raw material for road construction is taken into consideration, the asphalt pavement consumes twice as much energy as the concrete pavement, and if the raw material energy is not included, the energy consumption of these two pavements is equal. In the case of carbon dioxide emissions, ordinary concrete pavement discharges 40-60% more than asphalt pavement [26]. Another comparative study between hot mixed asphalt concrete pavement and continuously reinforced concrete pavement was conducted by [PERSON] and [PERSON] [26; 27] in the United States. They found that in the production stage of materials, the energy consumption of asphalt concrete pavement is about 40% higher than that of continuous reinforced concrete pavement. Most of the environmental indicators of asphalt concrete pavement are better than that of continuous reinforced concrete pavement. [PERSON] [28] concluded in his study that the energy value of asphalt pavement is about 90.8% higher than that of concrete pavement. During the production and maintenance of the pavement, the energy value of the asphalt concrete is higher than that of the cement concrete. In Canada, [PERSON] and [PERSON] [26] applied energy--the part of the energy that can be transformed into any form of energy--to study the energy consumption and environmental impact of asphalt and cement concrete. [PERSON] [29], through their study, which included accessory facilities of a highway, concluded that the energy consumption of cement concrete pavements is higher than that of asphalt concrete pavements. [PERSON] and [PERSON] [30], by analysing the energy consumption of asphalt concrete pavements and continuous reinforced concrete pavements, found that the continuous reinforced concrete pavement consumes more energy in the production and construction stage of materials, including the energy consumption of cement production. The energy consumption of cement production is the main factor, while the drying energy consumption of mixed aggregates is a significant factor affecting the energy consumption of asphalt pavement. Since 1996 until now, at least one study per year has been published that applies the methodology of road life cycle assessment. Although this allowed for the accumulation of knowledge in this field of research, there was no clear evolution of the scientific field during this period. In the current literature for pavement structures, there are contradictory results that occur from the use of different assumptions and the application of LCA methodology. The framework for life cycle environmental assessment is relatively complete after years of research, but there are still many shortcomings in the detailed model and data collection is also in the initial stage.