Sustainable Aggregates Production: Green Applications for Aggregate By-Products

Increased emphasis in the construction industry on sustainability and recycling requires production of aggregate gradations with lower dust (cleaner aggregates) and smaller maximum sizes—hence, increased amount of quarry by-products (QBs). QBs are usually less than 1/4 in. (6 mm) in size. This report provides findings of an industry survey conducted among Illinois aggregate producers on the annual production rate, excess QBs generated, and current application areas of QBs. In addition, a detailed laboratory study was conducted to characterize the engineering properties of QB materials produced in the primary, secondary, and tertiary aggregate production stages from four different quarries operating in the State of Illinois. Since unconfined compressive strength for QB materials was low (less than 11 psi), chemical admixture stabilizers such as Portland cement and Class C fly ash were used to improve the strength properties of QB materials. Significant increases in the strength of stabilized QB materials observed may indicate suitability of QBs for sustainable pavement applications. Recommendations are made on potential strategies to utilize excess fines by incorporating QB materials in pavement construction.Illinois Department of Transportation, R27-125Ope