Production of Bio-Rejuvenated Recycled Shingles (BR2S) for Pavement ConstructionEPA Contract Number: EPD15037
Title: Production of Bio-Rejuvenated Recycled Shingles (BR2S) for Pavement Construction
Investigators: Oldham, Daniel J.
Small Business: Bio-Adhesive Alliance Inc.
EPA Contact: Richards, April
Project Period: September 1, 2015 through February 29, 2016
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2015) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Building Materials
This SBIR Phase I project will develop a novel technology to convert swine manure to bio-rejuvenators that are green, low in cost and highly effective (more durable) to revitalize tear-off roofing shingles for reuse in pavement construction. Bio-Adhesive Alliance provides a sustainable and environmentally friendly technology to not only treat swine manure, but also to reuse tear-off roofing shingles, which otherwise end up in landfills.
The proposed technology provides a sustainable solution for two major environmental challenges in the agriculture and building industry in the United States and worldwide. In the agriculture industry, treatment of swine manure is a major problem, both environmentally and economically. One pig produces more than 5,000 gallons of manure per year. Currently, more than 120 million hogs are produced in the United States per year; this generates more than 6 billion gallons of swine manure that must be treated. More than 90 percent of swine manure is stored in lagoons, resulting in serious health and environmental problems. The remaining is being sold to farmers as fertilizers, with added costs to the hog farmers to store and deliver it. In both cases, hog farmers must pay to get rid of their swine manure. In the construction industry, it is estimated that approximately 10 million tons of Post-Consumer Tear-Off Scrap Shingles (TOSS) and 1 million tons of Manufactured Waste Scrap Shingles (MWSS) are being generated in the United States annually, around 9 million tons of which are being disposed of in landfills every year.
Bio-Adhesive Alliance’s proposed technology addresses these problems by converting swine manure into bio-rejuvenators, which are then used in combination with recycled shingles to make Bio-Rejuvenated Recycled Shingles (BR2S) for use in pavement construction. BR2S would be a complimentary, green, low-cost and easy-to-use source of mineral aggregates and rejuvenated asphalt. Accordingly, Bio-Adhesive Alliance’s solution will have significant environmental impacts on the agriculture and construction building industries by developing a business model based on a sound waste management solution for both swine manure and tear-off shingles.
Bio-Adhesive Alliance’s value proposition is in revitalizing old asphalt in roofing shingles. Each roofing shingle is composed of approximately 53 percent mineral aggregate and an average asphalt binder content of 28 percent; therefore, the recycling of 1 ton of asphalt shingles would be equivalent to reduction in consumption of 1 barrel of liquid asphalt. The price of liquid asphalt has increased dramatically within the last decade, from $250 per ton in 2004 to $635 per ton in 2014. Refineries are decreasing asphalt production by converting their asphalt binder into synthetic fuel and selling it at a much higher price. This in turn, has led to the shortage of asphalt binder and an increase in its price. As such, the pavement/asphalt industry is looking relentlessly for alternative liquid asphalt resources that meet Superpave PG specification. The proposed technology is superior to existing waste management solutions for aforementioned two waste streams since it produces an added-value product, BR2S, which could be figured in pavement construction as a complimentary, green and low cost source of mineral aggregates and rejuvenated asphalt.
To date, in spite of the fact that many states’ Departments of Transportation allow usage of recycled shingles in pavement construction, only a small percentage of shingles (< 5% by weight of paving mixture) is used. This is mainly due to the oxidized nature of asphalt found in roofing shingles, which adversely affects its compatibility and blending with virgin asphalt binder. In addition, asphalt plants face significant challenges associated with high variability in tear offs as well as their high moisture content and fiber dust generated when shingles are added to the plant, which make the quality control difficult. Therefore, Bio-Adhesive Alliance’s proposed bio-rejuvenator is to revitalize aged asphalt in roofing shingles and facilitate its compatibility and blending with virgin asphalt while its palletized and preprocessed nature will lend itself well to high standards of quality control. Accordingly, BR2S is designed to incorporate high percentages of roofing shingles while promoting their compatibility with virgin asphalt and facilitating the quality control. This in turn, results in lower pavement construction cost without compromising pavement performance while diverting huge amount of tear off shingles from landfills.
Based on Bio-Adhesive Alliance’s prior experimental results, it was found that inclusion of roofing shingles negatively impacts low temperature cracking properties of the paving mixture as evidenced by the reduction in fracture energy, ductility, and limit cracking temperature (LCT); however, the negative impact of roofing shingles was significantly alleviated by the introduction of bio-rejuvenator made from swine manure to the extent that BR2S clearly showed a four degree improvement in LCT. This was also reflected in associated critical energy release rate. Overall, introduction of bio-rejuvenator to recycled roofing shingles was found to be effective in enhancing rheological properties of resulting asphalt blend by enhancing compatibility and blending between oxidized and non-oxidized asphalt in shingles and virgin asphalt. This in turn improved miscibility between the two asphalts and prevented the phase separation. The observed improvement was attributed to the presence of amide functional groups in bio-rejuvenator of BR2S; the bio-rejuvenator molecules penetrate into the asphalt binder’s matrix changing its molecular packing. This in turn reduces clustering of asphaltene molecules and improves the interaction between the aged and non-aged asphalts facilitating their blending.
Bio-Adhesive Alliance’s main value proposition is in highly effective revitalizing oxidized asphalt in tear of shingles, reducing their variability and controlling their moisture content. This is mainly achieved by incorporating the company’s highly effective bio-rejuvenator into recycled tear off shingles followed by processing and palletizing the rejuvenated mixture to form BR2S. During the early, start- up years Bio-Adhesive Alliance will use a relatively simple business model: collect manure, process it in the company’s bio-reactors, convert it to bio-rejuvenator, combine it with recycled shingles, and palletize and sell it to asphalt plants as a complimentary, green and low cost source of mineral aggregates and rejuvenated asphalt. Due to its low cost and high effectiveness, Bio-Adhesive Alliance can sell BR2S at a very competitive price while maintaining a significant margin for the partner recyclers and the company itself. By focusing on Bio-Adhesive Alliance’s core competency, the company can maintain its completive edge in the market. By providing BR2S to asphalt plants, the company will enable them to use higher shingle percentages (to increase their revenue) while maintaining high quality mixtures; in addition, palletized nature of BR2S facilitates its usage while preventing formation of shingles’ fiber dusts which typically spread in plants when shingles are added into the mixtures; this in turn provides more efficient asphalt plant operation.