About the research
This research proposes to use quarry fines as a binding agent in unpaved roads. The road systems in the United States and Iowa consist of 50% and 60%, respectively, of granular-surfaced (unpaved) roads. The sustainability of unpaved roads is very important to the rural economy, since these roads provide access to rural land and enable the transportation of agricultural products. Any interruption in access can have a significant impact on agricultural productivity and the economy. Heavy traffic loads and freeze-thaw cycles can cause extensive damage to unpaved roads, leading to material loss, surface erosion, rutting, and potholes. The rate of deterioration (or damage) is directly correlated to the quality of the granular aggregate materials matrix used in the design of unpaved roads. Performance and long-term sustainability of granular roadways are dependent to a considerable degree on the quality of the aggregate materials used, which varies considerably from one source to another. Sometimes the quality of coarse aggregates is low and it crushes under traffic load, increasing the fines content in the aggregate matrix. In other cases, the quality of the aggregates is high, but the aggregates are floating on the road surface due to the lack of an adequate amount of fines within the aggregate matrix.
It is known that chemical stabilization can be applied to solve the binding issue of coarse aggregates in unpaved roads, however these methods are usually not economical and/or easy to apply and are also not sustainable. Therefore, it is important to find an alternative material to overcome this problem while making sure it is sustainable, economical and environmentally friendly. One of the alternative materials to use is quarry fines, which are generated at the approximate rate of 159 million metric tons (175 million tons) per year.
In this project, the research team proposes to conduct laboratory and field tests to examine the impact of inclusion of waste quarry fines in granular aggregate materials used in unpaved road designs, using materials collected from various quarries. Based on the laboratory test results, field test sections will be constructed using materials with different quarries. The field performance (abrasion resistance, freeze/thaw resistance, density, material loss, modulus, gradation change) of sections built with different quarry fines will be compared. Then, a comprehensive cost-performance and life-cycle cost analyses will be conducted to evaluate the cost effectiveness and sustainability of these unpaved roads to determine whether it is economically advantageous to add waste quarry fines into granular unpaved road materials.