Development of Bio-Based Polymers for Use in Asphalt, TR-639, 2014

Asphalt binder is typically modified with poly type (styrene-butadiene-styrene or SBS) polymers to improve its rheological properties and performance grade. The elastic and principal component of SBS polymers is butadiene. For the last decade, butadiene prices have fluctuated and significantly increased, leading state highway agencies to search for economically viable alternatives to butadiene based materials. This project reports the recent advances in polymerization techniques that have enabled the synthesis of elastomeric, thermoplastic, block-copolymers (BCPs) comprised of styrene and soybean oil, where the “B” block in SBS polymers is replaced with polymerized triglycerides derived from soybean oil. These new breeds of biopolymers have elastomeric properties comparable to well-established butadiene-based styrenic BCPs. In this report, two types of biopolymer formulations are evaluated for their ability to modify asphalt binder. Laboratory blends of asphalt modified with the biopolymers are tested for their rheological properties and performance grade. Blends of asphalt modified with the biopolymers are compared to blends of asphalt modified with two commonly used commercial polymers. The viscoelastic properties of the blends show that biopolymers improve the performance grade of the asphalt to a similar and even greater extent as the commercial SBS polymers. Results shown in this report indicate there is an excellent potential for the future of these biopolymers as economically and environmentally favorable alternatives to their petrochemically-derived analogs.

Bridge Deck Waterproofing Membrane Study, R-262, 1974

One of the main problems of bridge maintenance in Iowa is the spalling and scaling of the decks. This problem stems from the continued use of deicing salts during the winter months. Since bridges will frost or freeze more often than roadways, the use of deicing salts on bridges is more frequent. The salt which is spread onto the bridge dissolves in water and permeates into the concrete deck. When the salt reaches the depth of the reinforcing steel and the concentration at that depth reaches the threshold concentration for corrosion (1.5 lbs./yd. 3 ), the steel will begin to oxidize. The oxidizing steel must then expand within the concrete. This expansion eventually forces undersurface fractures and spalls in the concrete. The spalling increases maintenance problems on bridges and in some cases has forced resurfacing after only a few years of service. There are two possible solutions to this problem. One solution is discontinuing the use of salts as the deicing agent on bridges and the other is preventing the salt from reaching or attacking the reinforcing steel. This report deals with one method which stops the salt from reaching the reinforcing steel. The method utilizes a waterproof membrane on the surface of a bridge deck. The waterproof membrane stops the water-salt solution from entering the concrete so the salt cannot reach the reinforcing steel.

Developing Iowa’s Bio-science Workforce: The Role of the Community Colleges of Iowa In Creating Skilled Workers for the Emerging Bio-science/Biotechnology Sector, 2006

The Iowa economy is undergoing great change. Among the sectors deemed important to Iowa’s economic future is bioscience. Definition of what constitutes the bioscience sector but suggests it includes agricultural, medical, plant-life sciences, and related industrial activity.