Reducing pavement cost using biochar derived from Agaricus bisporus compost waste

OpenAlex · English

Biochar (BCh), a carbon-rich byproduct derived from the pyrolysis of biomass, is conventionally employed as a soil amendment in agricultural contexts but remains unexplored for geotechnical soil stabilization. This study pioneers the application of BCh synthesized from Agaricus bisporus Mushroom Spent Compost (MSC) via pyrolysis, combined with low-plasticity clay soil and alkaline activators, to engineer a novel composite termed Geo-Char (GCh). The research evaluates the efficacy of BCh and GCh in enhancing soil mechanical properties through Unconfined Compressive Strength (UCS) testing. Results demonstrate a 176% improvement in soil strength with a 10% BCh additive. When GCh activated with Sodium Hydroxide was incorporated, a 147% strength increase was observed; however, the use of Potassium Hydroxide as an activator was discouraged pending further mineralogical and chemical analysis. Mechanistic-empirical modeling revealed that both BCh and GCh significantly extend pavement service life. Life Cycle Cost Analysis (LCCA) quantified long-term economic benefits, with BCh reducing pavement lifecycle costs by 24% and GCh by 21–23%. These enhancements stem from the improved subgrade strength achieved by integrating MSC-derived additives (BCh/GCh) into pavement layers. The findings advocate for sustainable waste-to-material strategies in geotechnical engineering, emphasizing both performance and cost efficiency.