Characterization of Volume Change, Strength and Durability of Landfill Liner Materials with Inclusions of Industrial By-products

Mixture of expansive soil and sand can be efficiently used in semi-arid climates, with improved hydro-mechanical properties, as a landfill barrier material or road-base. The soil mixture can further be enhanced with industrial waste by-products, also creating an area for waste recycling. In this study, sand and expansive soil were selected from abundantly found local resources. The testing program consisted of determination of an optimum mixture of sand-expansive soil-additive, which would not experience formation of macropores due to swell-shrink behavior with the climatic effects and would possess low hydraulic conductivity, as well as improved strength. The additives were selected from the by-products of the materials used in the local construction industry, and included polymeric fiber (PF) and marble waste. The first stage of this study focused on the volume change and strength properties of sand stabilized expansive soil reinforced with polymeric fiber. Zeolite was also used as an alternative material to sand, mixing it in 1:1 ratio with the expansive soil forming a stable structure with improved properties. PF inclusions of 1%, 2% and 3% by dry mass indicated that hydro-mechanical properties were improved with an optimum amount of 2%. The second phase of this study assesses the suitability of expansive soil mixed with zeolite, readily obtained from natural reserves in Turkey, to be proposed as a landfill liner in a semi-arid climate. The choice of zeolite is due to its already well understood high adsorption capacity for heavy metals as well as its pozzolanicity. The volume change, strength, and hydraulic conductivity characteristics were studied with the effect of durability through aging. The results illustrated that expansive soil-zeolite mixture when used in 1:1 ratio attained improved strength characteristics with time iv over a curing period of 90 days. Therefore, it was concluded that a locally available expansive soil mixed with zeolite could be a good alternative to sand-Na-bentonite. In the third stage of the experimental program, marble waste, abundantly found as a by-product of construction industry, was evaluated as a secondary material to be utilized as potential stabilizer to improve the volume change and strength characteristics of sand-amended expansive soil. Marble waste obtained from two different sources with different gradations, denoted as marble powder (MP) and marble dust (MD) was also assessed for possible recycling by inclusion in stabilized soil mixtures. Volume change and strength tests were conducted on expansive soilsand mixtures with 5%, 10% and 20% waste marble inclusions over curing periods of 7, 28 and 90 days. The results indicated that 10% MP and 5% MD were the optimum amounts giving the best results. However, the soil mixtures displayed brittle behavior after marble addition, hence utilization of this waste is recommended for soils exposed to lower flexural loads only. Linear correlations of swell potential with flexural strength were obtained which could be potential empirical approaches to predict flexural strength based on swell-shrinkage behavior or vice versa for the soils studied. Keywords: Polymeric fiber, marble powder, zeolite, volume change, flexural strength, unconfined compressive strength.