Mechanical Properties Of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders

Download or read book Mechanical Properties of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders written by Ala R. Abbas and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot mix asphalt (HMA) is a mixture containing aggregates and asphalt binders prepared at specified proportions. The aggregates and asphalt binder proportions are determined through a mix design procedure such as the Marshall Mix Design or the Superpave Mix Design methods. Overall, the goal of determining such proportions is to establish an HMA mixture that will meet specific performance criteria. In addition, it is imperative to ensure that the asphalt binder will fully coat the aggregates and that the resulting mixture is workable and compactable. In order to ensure sufficient aggregate drying and coating, both the asphalt binder and the aggregates are heated to elevated temperatures ranging between 300oF and 325oF. The use of such high temperatures would result in lowering the viscosity of the asphalt binder which is the main factor affecting the coating and workability of asphalt mixtures. In recent years, a new group of technologies have been introduced to the United States that allow producing asphalt mixtures at temperatures 30 to 100oF lower than what is used in HMA. This group of technologies is commonly referred to as Warm Mix Asphalt (WMA). They are promoted as environmentally friendly green alternatives to HMA mixtures as they produce lower greenhouse gas emissions. This new group of technologies aims at reducing the viscosity of the asphalt binder through the addition of organic or chemical additives or by introducing cool water into the heated molten asphalt under controlled temperature and pressure conditions, resulting in so-called foamed asphalt binder. As a consequence, lower temperatures are needed during production for the asphalt binder to be absorbed by the aggregates.