Investigation of the Effect of Adding Biochar an‎d Natural Zeolite to Clay Soil as a Final Cover of Lan‎dfills for Reducing Greenhouse Gas Emissions an‎d Improving the Performance of Clay Layers in Controlling Lan‎dfill Gas Emissions.

4/21/2026 12:00:00 AM

Abstract Gas permeability in clayey soils is one of the key parameters influencing the performance of cover layers an‎d gas emission control systems in geotechnical projects, particularly in lan‎dfill applications. In this study, the gas permeability of a low-plasticity clay soil classified as CL was experimentally investigated considering the effects of relative compaction, confining pressure, an‎d the use of natural additives, including zeolite an‎d biochar. Soil specimens were prepared at different relative compaction levels an‎d subsequently tested in a triaxial apparatus under various confining pressures. In addition, the influence of adding zeolite an‎d biochar at weight contents of 5% an‎d 10% on gas flow behavior was eva‎luated. To assess the combined effects of the independent variables, the experimental data were analyzed an‎d modeled using Response Surface Methodology (RSM). The results indicated that relative compaction is the most influential factor controlling gas permeability. Among the additives, biochar exhibited a more pronounced effect in reducing gas flow, while zeolite an‎d confining pressure showed comparatively lower influences. Overall, the findings demonstrate that appropriate control of relative compaction, combined with the targeted use of natural additives particularly bioch can effectively limit gas migration in clayey soils.

واژگان كليدي: نفوذپذيري گاز، خاك رسي CL، تراكم نسبي، بيوچار، زئوليت طبيعي، سلول سه‌محوري، روش سطح پاسخ (RSM)

Keywords: Gas permeability; CL clay; Relative compaction; Biochar; Zeolite; Triaxial cell; Response Surface Methodology (RSM).

Aryan Sarafi

Hamidreza Razeghi-Jaber Mamaghanian