The Department of Civil Engineering is glad to announce that Dr Raviteja KVNS, Assistant Professor, has received the Best Paper Award for his paper titled “Compressibility Characteristics of Bentonite Amended Fly Ash Liners Exposed to Phosphate Contamination” at the 2nd International Conference RAISE 2023 (Recent Advances in Sustainable Environment) held on May 15-16, 2023. Dr Raviteja collaborated with Dr Janga Jagadeesh Kumar and Dr Krishna R Reddy, Civil, Materials and Environmental Engineering, University of Illinois Chicago for the research paper. Their cutting-edge research focused on developing alternate liner materials for waste containment systems.

Abstract

Waste containment systems like landfills, and impoundments are often lined with low permeable clays of hydraulic conductivity less than 10-7 cm/s. However, it is often challenging to get large volumes of low permeable clays near the project site. Conveyance of large volumes of clay from distant locations can be unsustainable due to the associated carbon emissions and energy costs, and not viable financially. Hence, there is a need to identify alternative liner materials without compromising on the containment capabilities. This study proposes the use of fly ash, amended with bentonite, as an alternative to the traditional liner systems. From preliminary studies, it is understood that a mixture of 80% fly ash amended with 20% bentonite is optimal to function as an effective liner material. However, the hydro-mechanical stability of liners needs to be investigated under different contamination scenarios. The present study reports the compressibility behavior of the proposed liner system under phosphate contamination, typically found in landfill leachate, impoundments, and stormwater retention ponds. One-dimensional consolidation tests were conducted on pure bentonite and fly ash with water to study the compressibility characteristics of individual materials. The optimum mix (80-20) was then tested at three different solutions exposure: water, 3.2 mg/L PO4-3-P and 12 mg/L PO4-3-P. It is depicted that the addition of 20% bentonite to fly ash did not affect the compressibility significantly, while the presence of phosphate contamination did not compromise the hydro-mechanical stability of the proposed liner system.