About the research
Iowa ranks as number one in the nation in egg production, and the Iowa Egg Council reports that between September 2019 and August 2020, Iowa produced nearly 16 billion eggs, meaning that each year Iowa egg industries are responsible for about 1 of 5 eggs consumed in the United States. Egg production adds significantly to the Iowa economy by contributing more than $2 billion in total sales. The cost of distributing in-shell eggs from Iowa to highly populated areas on the east and west coasts represents Iowa’s primary competitive disadvantage, so to reduce freight costs and compete more effectively against other states (e.g., Pennsylvania and California), Iowa has employed a production strategy of delivering approximately 70% of its eggs in liquid or dried-egg form, processed through integrated packing and breaking facilities to food manufacturers and other customers. Based on this strategy, increased liquid or dried-egg production is expected to ensure the price competitiveness of the Iowa egg industry. Consequently, while large amounts of eggshells are also generated from Iowa egg industries, they lie unused as value-added products and get dumped into landfills. Eggshells mainly consist of calcium carbonate (CaCO3) (i.e., up to 94%), identified as the primary element of calcium-based stabilizer materials (CSMs) with the capability for binding soil and aggregates through hydration, cation exchange, flocculation, pozzolanic reaction, and carbonation. The concept of using eggshells as bio-based cementing materials has therefore been investigated and successfully demonstrated overseas, targeting their use as new value-added products (e.g., cement replacement, soil stabilizer, masonry blocks, bone, and dental implants, etc.). Such proven success in other countries suggests the desirability of research in identifying effective and practically-implementable ways of using Iowa eggshell waste to improve engineering properties of Iowa geo-materials (e.g., frost-susceptible soils and low-quality local aggregates) used in either pavement or gravel road systems. It is hypothesized that such an innovative and sustainable approach may lead to the achievement of stronger and more durable pavement foundation and gravel road systems in Iowa.