Effects of Hospital Waste Ash as a Partial Cement Replacement on the Properties of C-30 Concrete
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Date
2026-06
Authors
Birtukan Dejene
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Publisher
Addis Ababa University
Abstract
In Ethiopia, rapid urbanization and new environmental regulations have led to rising construction costs and material shortages. As cement demand continues to grow, identifying sustainable alternatives has become essential. This study explores the utilization of hospital waste ash (HWA) as a cement partial replacement in the properties of C-30 concrete to reduce cost and improve mechanical properties.
The hospital waste ash was collected from Yekatit 12 Medical College Hospital. The aim of this research is to is to identify the optimum percentage of hospital waste ash (HWA) as a partial replacement for cement and to investigate its effect on the fresh and hardened properties of concrete. In addition, the research objectives to assess the cost-effectiveness of incorporating hospital waste ash as a sustainable alternative to conventional cement.. The properties of materials were identified to get information about the material for the next steps and these tests was conducted using ASTM standard. This hospital waste ash was replacing the cement at the percent of 0%, 5%, 10% and 15%. After identification of all properties of material design mix was prepared according to ACI method. Casting of concrete was made by using mechanical mixer and for compressive, flexural and split tensile strength test then cured for 3th, 14th and 28th day for those percentage of replacement. In addition, mechanical property test permeability test performed for all percentage of replacement.
The setting time of concrete increases when hospital waste ash is added to the cement paste, a trend observed for both initial and final setting times across all replacement percentages. Similarly, workability decreases: the slump test showed lower slump values as the amount of hospital waste ash increased.
The experimental results revealed that replacing 5% of cement with hospital waste ash significantly increased compressive, tensile, and flexural strengths among all mixes. Overall, a 10% replacement level was identified as the optimum proportion, showing good performance compared to other samples. However, concrete strength significantly decreased at replacement of 15% Within.In terms of durability, the 5% hospital waste ash mix showed low permeability, which means it is more resistant to water penetration, while the 15% mix showed high permeability. According to the results, a partial replacement of cement with hospital waste ash up to 10% improves the density and durability of concrete. On the other hand, there is an increase in higher replacement. porosity and decrease compactness. In addition to testing the mechanical properties, an analysis of the curing water was performed to check for heavy metals. The results showed that lead was present at 0.02 ml/g, while cadmium was not detected.
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Keywords
Partial replacement, hospital waste ash, heavy metals, incineration