Abstract
The concrete industry has a plethora of negative impacts on the globe and environment. Also, with the depletion of natural resources that are used in concrete and cement production, many research attempts are focused on finding alternatives or incorporating waste materials into concrete mixes. Seashells are some of these waste materials that are rapidly accumulating on seashores and landfills, causing an environmental problem of their own. This review paper is focused on the utilization of various types of seashell waste materials in concrete as partial cement replacement. The utilization of seashells in concrete helps in seashell waste management and in producing cost-efficient concrete. The paper summarizes the previous research attempts to produce burnt seashell to partially replace cement in different proportions. It also presents the physical and mechanical properties of seashell ash and the produced concrete. The literature review has justified the use of seashell waste ashes for cement partial replacement in sustainable concrete. The study shows that incorporating seashell ash resulted in reduced early compressive strength of concrete. The strength increased with age due to hydration of calcium oxide, but it remained less than control samples, especially at high percentages of replacement. The flexural and splitting tensile strength was improved due to the development of good bonding between the binder matrix and aggregates and this increased the modulus of elasticity. However, some studies reported a decrease in splitting tensile strength. The absorption and porosity of concrete at low percentages of replacement are less than the standard. However, these values are increased with higher levels of replacement. Seashell ash generally reduces workability. The ash also reduces concrete permeability after long periods of curing. It can be established that there is a possibility for incorporating seashell in concrete as a binder material for sustainable construction purposes.
•Seashells as waste materials and possibility of usage in concrete.•Reviewing partial replacement of cement with seashell ashes in concrete production.•Methods of preparing and burning seashells into ashes.•Impacts on fresh and hardened concrete properties.•Recommendations for further investigations on seashells as building materials.