Assessment of strength and durability of an eco-friendly high strength lightweight concrete by incorporating treated crushed coconut shell aggregates and ground granulated blast furnace slag.

The rising demand for concrete is rapidly depleting finite resources of its constituent materials, such as sand and gravel. Addressing this issue demands alternative recycled or bio-based eco-friendly sources for aggregates. In recent decades, crushed coconut shells have been utilized as an alternative for coarse aggregate to produce concrete. However, the key challenges in producing structural-grade coconut shell aggregate concrete (CSAC) include high cement consumption and high absorption of the coconut shell aggregate (CSA). Therefore, in this study, cement was partially replaced with GGBFS (10% and 20%) to reduce cement consumption, and treated CSA was used (using grout coating) to improve the quality of CSA in CSAC. The study aimed to evaluate the strength and durability properties of CSAC with GGBFS and treated CSA. The properties of CSAC mixes such as compressive strength, water absorption, sorptivity, rapid chloride penetration, and resistance to chemical attacks were evaluated. The experimental studies show that the water absorption value of treated CSA concrete with 10% GGBFS mix(T/10) was 10.69% less compared to untreated CSA concrete with 10% GGBFS mix(U/10) at 180 days, respectively. Similarly, the sorptivity of the T/10 mix was 11.86% less compared to U/10. The 180-day compressive strength of the T/10 mix was 7.51% and 2.32% more compared to the control CSAC mix(U/0) and U/10 mix, respectively. The environmental impacts of CSAC were evaluated by fast-track LCA and compared with conventional aggregate concrete (CC). The carbon footprint values of the T/10 mix and CC mix were 462.51 kg COe/ m and 483.82 kg COe/ m, respectively. This study proves that the strength, durability, and ecological properties of CSAC were improved by incorporating GGBFS and treated CSA into the concrete mix.