Sustainable Asphalt Mixes with High RAP Contents and Rejuvenating Agents: Laboratory Evaluation and Plant Validation

在加拿大，沥青混凝土用于大约90%的铺面道路和高速公路。材料成本是沥青混合料生产中最昂贵的部分，约占热拌沥青混合料（HMA）生产成本的70%。柔性路面可以在其使用寿命结束时回收，以重新使用其一些有价值的成分，如沥青水泥（AC）和矿物骨料。再生沥青路面（RAP）是目前世界上回收利用最多的材料之一。因此，在RAP中重复使用老化的沥青水泥（AC）可以降低对原始AC的需求，也有助于建设项目的经济性。尽管在新的混合料生产中重复使用RAP具有若干环境和经济效益，但其氧化AC的性质限制了其使用。目前，RAP在表面混合物中的使用仅占总混合物的20%。最大限度地提高RAP的使用需要进一步的调查，以确保RAP掺入混合表现优于，或至少相同，传统的沥青混合料。为此，再生老化的沥青结合料是将老化的结合料的性质恢复到类似于原始结合料的条件的有希望的方法。在这个项目中，帝国石油公司与滑铁卢大学合作，用RAP取代70%的原始成分，生产可持续的沥青混凝土混合料。为此，将确定两种与加拿大国内材料兼容的再生油，确保新的沥青混凝土混合料能够承受加拿大极端的气候条件和不断增长的交通负荷。该项目的成果将是一份综合文件，为加拿大沥青行业的专业人员提供实用建议，以更好地利用RAP生产更经济、可持续和环保的沥青混合料。即使再循环率提高5%，也将导致每年减少60多万吨原始骨料的使用。因此，这项研究计划的成功将对我国的经济和环境产生真实的重大积极影响。

Asphalt concrete is used in about 90 percent of the paved roads and highways in Canada. Materials costs are the most expensive part of asphalt mix production, comprising about 70 percent of the cost to produce Hot Mix Asphalt (HMA). A flexible pavement can be reclaimed at the end of its service life to reuse some of its valuable ingredients such as asphalt cement (AC) and mineral aggregates. Reclaimed Asphalt Pavement (RAP) is now one of the most recycled materials in the world. Therefore, reusing the aged asphalt cement (AC) in RAP can lower the need for virgin AC and also help with the economy of construction projects.In spite of the several environmental and economic benefits of re-using RAP in a new mix production, the nature of its oxidized AC limits its usage. Currently, use of RAP in surface mixes merely reaches 20 percent of the total mix. Maximizing the RAP usage requires further investigations to ensure that RAP incorporated mixes perform better than, or at least the same as, the conventional asphalt mix. To this end, rejuvenating the aged asphalt binder is a promising approach to restore the properties of an aged binder to a condition that resembles that of virgin binders. In this project, Imperial Oil is coming together with the University of Waterloo to produce sustainable asphalt concrete mixes by replacing up to 70% of their virgin ingredients with RAP. For this purpose, two rejuvenating oils will be identified that would be compatible with the domestic materials in Canada, ensuring that the new asphalt concrete mixes withstand the extreme climatic conditions and growing traffic loading in Canada. The outcome of this project will be a synthesis document that provides practical recommendations to the professionals of the Canadian asphalt industry for a better use of RAP to produce more economic, sustainable and environmentally friendly asphalt mixes. The increase of recycling rate by even 5% would lead to a reduction of the use of virgin aggregates by more than 600,000 tons annually. Therefore, the success of this research program would have a real significant positive impact on the economy and the environment of our country.