Date of Award
Doctor of Philosophy
Civil, Construction, and Environmental Engineering
R. Christopher Williams
Historically, growth of bio-based chemical products in the world market has typically been stunted due to their higher production costs as compared to crude petroleum derived products. However due to the rising cost of oil, increasing demand for environmentally friendly products from a growing population and limited amount of nonrenewable resources, growth for bio-based chemical products has increased. This market growth has propelled the number and size of bio-refineries to increase in the past 10 years.
However, the rise in the cost of oil has been accompanied by soaring prices for asphalt because of reductions in its supply. This reduction is primarily due to oil refiners maximizing on the production of transportation fuels through coking. As a result, a substantial amount of binder is produced that cannot be used for production of asphalt mixtures.
Warm mix asphalt occurs when mixing and compaction temperatures are lowered by 20°C to 55°C in the production and laydown of asphalt mix. This has also led to the development of bio-derived material additives for warm mix asphalt applications. Depending on the production process, bio-refineries can produce a sizable amount of material with surfactant characteristics. Due to surfactant characteristics, these materials can be used as a bio-based warm mix asphalt (WMA) additive technology.
Within this thesis, a bio-derived material - isosorbide distillation bottoms (IDB) -was studied as a warm mix asphalt additive technology, as opposed to other commercially available additive technologies, through a thorough examination of binder rheology and mix performance with various asphalt binders. The first step of this study was to investigate binder rheology to determine the optimum dosage rate of the IDB to various asphalt binders for use in warm mix asphalt. This part of the work resulted in an estimated dosage rate of 0.5% by weight of the total binder. Then, the additive was blended at the recommended dosage rate of 0.5% to create binders for use in mix production. Warm mix asphalt mixtures were produced for testing at intermediate and low temperatures and compared to warm mix asphalt without an additive and with commercially available additives at the recommended dosage rate. The results showed that IDB performs statistically the same as the other commercial additives; as well as, the same as the control mix. IDB neither harms nor benefits the mixes.
Joseph Herbert Podolsky
Podolsky, Joseph Herbert, "Investigation of bio-derived material and chemical technologies as sustainable warm mix asphalt additives" (2014). Graduate Theses and Dissertations. 14275.