Study of Mechanical Properties of Concrete Using Municipal Solid Waste Incinerated Ash and Iron Ore Tailings as Sustainable Material Substitutes

Abstract

The present work focuses on the sustainable development of M25 concrete by partially replacing cement with Municipal Solid Waste Incinerated Ash (MSWIA) and by substituting natural sand with Iron Ore Tailings (IOT). A series of mixes were produced with MSWIA in the range of 5% to 20% and later IOT was introduced from 10% to 40% to study the changes in mechanical behaviour. For every combination, compressive strength cubes, split tensile cylinders and flexural beam specimens were tested after 28 days of curing. The results indicated that replacing 10% cement with MSWIA gave the highest improvement in compressive, split tensile and flexural strength when compared with the normal mix, while further replacement reduced the strength gradually. After fixing 10% MSWIA as optimum, replacement of sand with IOT showed maximum strength around 20% and then a slight reduction was noticed for higher percentages. From the overall observations, both MSWIA and IOT were found suitable for use at moderate levels and they contributed to strength enhancement as well as reduction of natural material consumption. Thus, the combined use of MSWIA and IOT provides a promising and eco-friendly alternative for conventional concrete without compromising required engineering performance.

Introduction

Cement-based concrete is essential for modern infrastructure but has a high environmental cost, contributing about 7–8% of global CO? emissions and causing significant resource depletion. To address these sustainability concerns, this study investigates the use of Municipal Solid Waste Incinerated Ash (MSWIA) as a partial cement replacement and Iron Ore Tailings (IOT) as a partial fine aggregate (sand) replacement in M25 grade concrete.

MSWIA, obtained from municipal waste incineration, contains reactive mineral oxides that can contribute to cementitious behavior when properly processed. IOT, a by-product of iron ore mining, is rich in silica and alumina and can serve as an alternative to natural sand. The combined use of these materials supports waste valorisation, reduces landfill disposal, conserves natural resources, and lowers the carbon footprint of concrete, aligning with circular economy principles.

A detailed literature review confirms that both MSWIA and IOT can be effectively used in concrete at controlled replacement levels. Experimental investigations were conducted by replacing cement with MSWIA at 5%, 10%, 15%, and 20%, and sand with IOT at 10%, 20%, 30%, and 40%, while maintaining consistent mix proportions and curing conditions. Mechanical properties—compressive, split tensile, and flexural strength—were tested at 7 and 28 days.

Results show that 10% replacement of cement with MSWIA yielded the best overall mechanical performance. When combined with 20% replacement of sand using IOT, the concrete achieved optimal compressive, tensile, and flexural strengths comparable to or higher than the control mix. Higher replacement levels of either MSWIA or IOT led to reduced strength due to dilution of the cement matrix and reduced workability.

Overall, the study demonstrates that moderate use of MSWIA and IOT can produce sustainable, low-carbon concrete without compromising structural performance. The optimal combination of 10% MSWIA and 20% IOT offers a practical and environmentally beneficial alternative to conventional concrete, addressing both waste management and resource conservation challenges.

Conclusion

The outcomes of the experiments conducted in this study can be summarized as follows: 1) In the present investigation, cement was partially replaced with MSWIA at varying levels ranging from 5% to 20% in OPC. The results show that the optimum mechanical performance occurs at a 10% replacement level. At this percentage, the compressive strength, split tensile strength, and flexural strength reach 37.5 MPa, 3.73 MPa, and 4.29 MPa, respectively, representing increases of 8.5%, 13.3%, and 3.37% compared with the control mix (M0). 2) After identifying the optimum MSWIA content, sand was partially substituted with IOT. The highest strength values were obtained at a 20% IOT replacement. At this level, the compressive strength, split tensile strength, and flexural strength were recorded as 36.2 MPa, 3.40 MPa, and 4.57 MPa, showing improvements of 4.33%, 3.35%, and 4.57% over the reference mix (M0). 3) Overall, the study demonstrates that the maximum strength is achieved when 10% of cement is replaced with MSWIA, after which the strength gradually decreases up to the 20% level. When IOT is used as a partial replacement for sand, the optimum performance occurs at 20% replacement, beyond which strength begins to decline as the replacement reaches up to40%. In all optimal mixes incorporating MSWIA and IOT, the compressive strength remains higher than that of the reference concrete.

References

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Copyright

Copyright © 2025 S. Waris Muzammel, T. Chandra Sekhara Reddy. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.