## 2 Literature Review
[16] achieved similar results; the authors found that pavement construction and deconstruction have less impact on the pollution than the material production, transporting and recycling processes. Furthermore, [PERSON] et al. [17] noted that the volatile organic compounds generated during asphalt pavement production have a negative impact on the atmospheric ecosystem and that this problem has raised increasing concerns globally in recent decades. [PERSON] et al. [18] also revealed that asphalt production, compared to other processes, led to the most significant carbon emissions. The greenhouse gas (GHG) emissions are an essential primary criterion for environmental evaluation [19]. From the case studies provided in [20], asphalt production was identified as the process generating the most GHG emissions. [PERSON] et al. [21] presented a comparative analysis of GHG generation while employing various types of equipment used in different construction activities. In the study by [PERSON] et al. [22], a framework was developed for estimating GHG emissions for land-use changes. Due to the necessity of heating and mixing the aggregate and binder [15], a HMA plant uses more than half of the energy and generates a similar amount of global warming emissions in the production of materials. The asphalt industry is continuously attempting to reduce its emissions due to the problem of global warming. The emissions can be reduced during mixing by decreasing the temperatures and compaction processes without affecting the quality of the mixture. This is realised by implementing various available industrial technologies [23], for example, by using warm-mix asphalt (WMA) technology at 120 \({}^{\circ}\)C or lower temperatures; for HMA, 160 \({}^{\circ}\)C and higher temperatures can be used. [PERSON] et al. [24] performed comprehensive tests and stated that, in view of the characteristics of the mixing plant and the temperature drop during the construction procedure, the following construction temperatures are recommended: an aggregate heating temperature of 155 \({}^{\circ}\)C, a mixing temperature of 150-160 \({}^{\circ}\)C, a discharging temperature of 150-160 \({}^{\circ}\)C, a laydown temperature of 145-155 \({}^{\circ}\)C, an initial compaction temperature of 135-145 \({}^{\circ}\)C, a secondary compaction temperature of 130-140 \({}^{\circ}\)C and a final compaction temperature higher than 90 \({}^{\circ}\)C. [PERSON] et al. [25] also noted that reduced temperatures provide a greener technology as emissions are reduced at the plant and the construction site. The mixing temperature for binders is usually chosen by a pavement engineer based on the specific \"viscosity\" and gradation of the HMA. The pollutant emissions are evaluated in a lab by applying a comprehensive experimental design [26]. As the HMA manufacturers are required to meet the airborne emission thresholds, it is essential to define ways to measure those emissions. In [27], the authors investigated the influence of the equipment operating parameters on the airborne emissions, focusing on gaseous organic compounds. [PERSON] et al. [28] presented a study in which an analysis of the environmental benefits derived from cleaner production technology for manufacturing asphalt mixtures is provided. The air pollutant emissions from the construction operations can be evaluated by estimating, benchmarking and monitoring at the pre-construction and construction stages [29]. The particulate matter emissions filtered out in a pulse-jet filter unit were analysed in [30]. The separation efficiency of the cyclone separator was investigated in [31]; the authors used an inlet flow with particle concentration within a range from 5 to 2000 mg/m\({}^{3}\) for the research. It was found that the efficiency of the device increases as the inlet flow gets higher. The emission problem, while using numerical modelling, was investigated in [32].