Effects of Quarry and Recycled Concrete Waste as Rapid Use Stabilizers for Clay Soils (#1618)

Authors

Leon, Lee Philbert

Abstract

Construction in clay subgrades is challenging due to their shrinkage, swelling and strength behavior. The production of cement and lime for ground improvement has a significant negative environmental impact and thus there is a need to find novel, sustainable and economical soil stabilization approaches. The increase in the use of construction and demolition waste materials in the design and construction of infrastructure has helped to preserve our environment by reducing the number of wastes deposited in landfills and supports the conservation of our rapidly diminishing natural resources. The objectives of this research are to stabilize expansive clay with dosages (1, 5, 10, 20%) of cement, limestone dust and recycled concrete aggregate (RCA) fines; and to evaluate the short-term (12hrs) mechanical properties of the stabilized soil in the laboratory. It was found that for rapid use, the stabilized material showed improvement at estimated optimal dosages of 9% cement, 10% limestone dust and 11% recycled concrete aggregate. It was further revealed that optimum dosages resulted in high compaction density, improved strength, and limited swelling, while the cement was shown to be the most stable in improving the plasticity index. In summary, unconventional waste material stabilizers mostly improve the mechanical properties of natural soil. These outcomes of the study are principally useful to road designers since it validates that the construction waste aggregates can be implemented as a replacement with or without cement for the stabilization of clay soils. It further demonstrates the potential for recycling and reuse of construction, quarry, and asphalt plant waste as aggregates, to be efficient methods that are beneficial in protecting natural resources and the environment, thereby improving waste management. The economic validation of including recycled concrete aggregate fines and limestone dust as cement replacement would differ for each country, nevertheless, the reduction in carbon emissions is its undoubted merit, which is a significant contribution to a country’s climate change ambitions to achieve low carbon footprints.