Lifecycle impact assessments of ternary concrete modified with shea nutshell ash and ground oyster seashell

Recycling waste materials as eco-friendly cement substitutes to reduce CO₂ emissions and energy use, lower costs, and protect natural resources used in cement production is crucial. This study evaluates the effects of shea nutshell ash (SNA) and ground Oyster seashell (GOS) on the compressive strength and sustainability of ternary blended concrete (TBC). Shea nutshells and Oyster seashells were repurposed at controlled conditions, generating SNA and GOS. A 5-15% of both SNA and GOS was used as partial weight replacement for cement. The concrete mixes were designed with grades 25 and 30 MPa, and the compressive strength of the concrete samples was tested after 28 days of curing. The embodied energy (EE), global warming potential (GWP), sustainability score, and eco-strength efficiency of TBC samples were evaluated under cradle-to-gate constraints. The results indicated that the compressive strength met the design strengths at 5-10 wt% SNA and GOS replacement levels after 28 curing ages. Compared to the control samples, EE and GWP decreased by 8-30% and 10-29%, respectively, with increasing SNA and GOS dosages at 5-15 wt% substitutions. At 5-10 wt% replacement levels, the sustainability score, and eco-strength efficiency of TBC samples increased by 3-12% and 3-5%, respectively, compared to conventional samples. Ultimately, incorporating 10 wt% SNA and 10 wt% GOS in TBC production meets the required compressive strength, and is environmentally sustainable, facilitating sustainable concrete production and the circular economy.