The integration of circular economy principles within the cement industry plays a vital role in addressing climate change by reducing carbon emissions, promoting resource efficiency, and advancing sustainable construction materials. Herein, this study addresses the environmental issues stemming from the annual global production of over 17 million tons of crustacean and mollusk shell waste, commonly disposed of in landfills or oceans. It explores the reuse of crab shell powder (CSP) as a partial replacement for cement in mortar and ferrocement formulations, aiming to enhance sustainability by valorizing this abundant waste material. Mortar samples were prepared by substituting cement with CSP at 10% and 20% by weight, maintaining a 1:3 cement-to-sand ratio, and tested in accordance with the Bureau of Indian Standards (IS4031 and IS 2386 Parts 1–3, and IS 383:2016). Physical property assessments indicated that the inclusion of 10% CSP led to a 42% increase in consistency value, while increasing CSP content to 20% resulted in a 4.62% rise. Specific gravity experienced reductions of 13.46% and 18.26% for 10% and 20% CSP mixes, respectively. Regarding setting times, the initial set prolonged by 20.15% with 10% CSP but shortened by 14.28% when the CSP dosage was increased to 20%. Similarly, final setting time was extended by 4.76% for the 10% CSP blend but was decreased by 21.42% in the 20% replacement scenario. Flexural strength tests on ferrocement panels with a mortar mix ratio of 1:2 showed that a 10% CSP addition caused a 14.28% decrease in flexural strength, while increasing CSP to 20% led to a 28.5% reduction. Compressive strength results after 28 days of curing revealed a decline of 12% and 25% for the 10% and 20% CSP mixes, respectively. The water-to-cement ratio exhibited a slight decrease with the incorporation of CSP. Overall, these outcomes highlight that CSP influences various cementitious properties, notably diminishing mechanical strengths at higher substitution levels. This underscores the importance of optimizing the mix design and processing techniques to balance structural performance with sustainability goals. • CSP Substitution: 10% CSP increased consistency by 42%, enhancing mortar workability. • Specific Gravity Change: Specific gravity decreased by 13.46% with 10% CSP addition. • Setting Time Variations: Initial setting time rose by 20.15% for 10% CSP, impacting curing. • Strength Reduction: 20% CSP mixes showed a 28.5% decrease in flexural strength. • Compressive Strength Impact: Compressive strength declined by 25% with 20% CSP after 28 days.
Karuthakannan et al. (Wed,) studied this question.