# A Practice for the Application of Waste in Road Asphalt Pavements in an Eco-Friendly Way
## 4 Conclusions  
In conclusion, base and binder layers of road asphalt pavements were designed by introducing reclaimed asphalt Pavement and Construction and Demolition Waste as coarse aggregates, while Jet Grouting Waste and Fly Ashes as a filler. A total of four hot asphalt mixtures were investigated for the binder layer and five asphalt mixtures for the base layer, of which two are hot asphalt mixtures and two are cold recycled mixtures. First, a leaching test of the marginal materials was carried out, and their physical properties were assessed to ascertain compliance for reuse in asphalt mixtures. The results showed the following points:  
* HMA\({}_{\text{binderJGW}}\) solution has the best mechanical properties compared both to the traditional asphalt mixture HMA\({}_{\text{binder}}\) (increase of S (+144%), MS (+86%), ITS (+23%), ITSR (+10%), ITSM (+13% at 10 \({}^{\circ}\)C, +18% at 20 \({}^{\circ}\)C and +60% at 40 \({}^{\circ}\)C) and N\({}_{\text{f}}\) (+80%), reduction of RD (\(-\)7%)) and to all remaining solutions (improving on average by 26% all the engineering performance compared to both HMA\({}_{\text{binderCDW}}\) and HMA\({}_{\text{binderFA}}\)). * The cold asphalt mixtures for the base layer returned higher resistance to the permanent deformations (lower RD) compared to the traditional HMA\({}_{\text{base}}\); in particular, CMRA\({}_{\text{RAPJGW}}\) showed the best engineering performance indicators, returning higher stiffness at 40 \({}^{\circ}\)C, MS, ITS and ITSM (+27%, +10% and +68%, respectively) than HMA\({}_{\text{base}}\). * In terms of environmental and human health performance of the life cycle, HMA\({}_{\text{binderFA}}\) has the best performance between the mixtures for the binder layer, bringing on average a 2% reduction of all impact category indicators compared to HMA\({}_{\text{binder}}\), HMA\({}_{\text{binderCDW}}\) and HMA\({}_{\text{binderJGW}}\), above all due to lower OBC and the absence of the crushing phase of FA; instead, HMA\({}_{\text{binderJGW}}\) brings on average 1.5% reduction of all impact category indicators compared to HMA\({}_{\text{binder}}\) but reaches 8% lower GWP, A, OFT, OFH and FR than HMA\({}_{\text{binderCDW}}\). * CMRA\({}_{\text{RAPJGW}}\) is the most environmentally performing alternative compared to all the other hot (\(-\)35% on average for all impact indicators) and cold asphalt mixtures (\(-\)4% on average for all impact indicators) for the base layer. Specifically, the impact indicators IR, OFT, and MR of CMRA\({}_{\text{RAPJGW}}\) are on average 12% lower than CMRA\({}_{\text{RAPJ}}\) due to lower gaseous and particulate emissions in air and minerals consumption to produce the aggregates and cement. * MCDA and sensitivity analysis made it possible to identify which of the alternatives envisaged represents the most favourable solution in view of the indicators which are taken into account in a decision-making process for the construction and maintenance of a road pavement, such as high and low-temperature engineering performance, moisture resistance and environmental and human health performance. With a view to reducing raw materials consumption, decreasing greenhouse gas emissions and increasing the service life of asphalt pavements, it was possible to state that, when the operative conditions require the best mechanical performance independently from the average service temperature and humidity, HMA\({}_{\text{binderjGW}}\) results the best alternative. Instead, when decision-makers look for a solution that not only produces the lowest environmental impacts during its useful life but at the same time returns the best resistance to high temperature conditions, the preference is the adoption of the CMRRARPJGW solution. The following are available online at [[https://www.mdpi.com/article/10.3390/app11199268/s1](https://www.mdpi.com/article/10.3390/app11199268/s1)]([https://www.mdpi.com/article/10.3390/app11199268/s1](https://www.mdpi.com/article/10.3390/app11199268/s1)).