# A Practice for the Application of Waste in Road Asphalt Pavements in an Eco-Friendly Way
## 3 Results and Discussion
### System Description and LCI of Asphalt Mixtures
#### 3.2.4 Production, Laying and Compaction of Asphalt Mixtures  
The section describes the inventory flows of 1 m\({}^{3}\) of the produced, laid and compacted road asphalt pavement mixtures.  
Different processes were considered for the hot asphalt mixtures and cold in-place recycled asphalt mixtures, as described below:  
During the hot in-plant production (see Figure S3i), the input and output flows of all HMA solutions were assumed to be the same. The unit processes included the following operations and parameters mainly provided by local contractors: (a) the transportation of coarse aggregates and sand from stockpiles to the mixing equipment using a wheel loader with a productivity of 60 m\({}^{3}\)/h powered by diesel fuel; (b) the natural gas consumption for drying aggregates in the drum dryer of the production plant was equal to 8.79 m\({}^{3}\)/t; (c) the electricity consumption during the bitumen storage at 180 \({}^{\circ}\)C and mixing the aggregates, fillers and bitumen was equal to 4.37 kWh/t; and (d) the NMVOC emission to air for each ton of the produced hot asphalt mixture was 0.19 g according to the United States Environmental Protection Agency (2004) [80]. The hot asphalt mixtures were hauled over a distance of 20 km to the construction site by trucks. Afterwards, 1 m\({}^{3}\) of an asphalt mixture was laid by a paver and compacted by a roller machine (both pieces of equipment had a productivity of 45 t/h). The production and transportation of the hot asphalt mixtures account for the global emission of 15.8 kg CO\({}_{2}\)/m\({}^{3}\), while the laying and compacting operations produce 6.2 kg CO\({}_{2}\)/m\({}^{3}\).  
For the cold in-place recycled mixtures (see Figure S3i), the natural raw materials were hauled from the asphalt plant to the construction site by different trucks. The milled RAP was placed over the surface by a motor grader with a productivity of 1815 m\({}^{2}\)/h. A pulvimixer was utilized to mix and bind together the natural aggregates, marginal materials (RAP or RAP and JGW), cement, water and bitumen emulsion (see Table 2b) supplied at the construction site and then lay the resulting mixture on the pavement surface at a productivity of 750 m\({}^{2}\)/h. Subsequently, the cold mixture was compacted to a desired bulk density (Section 2.1) using a large pneumatic tire roller and a large vibratory steel wheel roller with productivities of 45 t/h.  
In synthesis, the lower heating temperature (60 \({}^{\circ}\)C) of the cold in-place recycling operations as compared with that of HMA production (180 \({}^{\circ}\)C) required a lower amount of fuel and thus reduced the CO\({}_{2}\) emissions by 20 kg CO\({}_{2}\)/m\({}^{3}\) during the laying and compaction operations.  
The CO\({}_{2}\) emissions in the end of life phase that involved the demolition and disposal of the old milled asphalt pavements (Figure S3i,ii) were equal for all the analysed asphalt mixtures (48.4 kg CO\({}_{2}\)/m\({}^{3}\)) and, therefore, were not considered further in this study.