Experimental Investigation of the Effect of Slag and Fly Ash Pozzolanic Materials as Cement Replacements on the Compressive Strength of Concrete

Subject Areas : Advanced Materials in Structural Engineering

shahab fallah ¹ , amin zamanian ² , ahmadreza mokhtari ³ , peyman shadman heidari ^{4 *}

1 - Department of Civil Engineering, ET.C, Islamic Azad University, Tehran, Iran
2 - Department of Civil Engineering, ET.C, Islamic Azad University, Tehran, Iran
3 - Department of Civil Engineering, ET.C, Islamic Azad University, Tehran, Iran
4 - Department of Civil Engineering, ET.C, Islamic Azad University, Tehran, Iran

Received: 2025-05-15 Accepted : 2025-06-10 Published : 2025-07-06

Keywords: Sustainable concrete, Fly ash, Slag, Compressive strength, Cement replacement,

Abstract :

Portland cement is one of the main materials used in the construction industry and is responsible for a significant share of global greenhouse gas emissions. Therefore, using pozzolanic materials and industrial by-products such as fly ash and blast furnace slag as partial replacements for cement is considered an effective approach toward reducing environmental impacts and promoting sustainable concrete. In this study, the compressive strength of concrete was investigated by partially replacing cement with fly ash at 10%, 20%, and 30%, and with slag at 20%, 30%, and 50%. A control mix without any pozzolanic additives was also prepared for comparison. Cube specimens were cast according to ASTM C109 and cured under laboratory conditions for 180 days. After the curing period, compressive strength tests were conducted on all samples. The results showed that incorporating fly ash and slag can improve the long-term compressive strength of concrete, although the extent of improvement depends on the replacement percentage and type of material used. According to researches done, replacing 20% of the cement with fly ash and 20% with slag resulted in the highest increase in compressive strength at 180 days compared to the control mix. The comparison indicates that these optimal replacement levels contributed effectively to pozzolanic reactions and the development of a denser microstructure over time.

References:


[1] Parveen, S., Sharma, M., & Jain, D. (2023). Strength enhancement of fly ash concrete at prolonged curing ages. Construction and Building Materials, 375, 130939.
[2] Kumar, A., Singh, P., & Al-Fakih, A. (2024). Recent advances in geopolymer concrete using GGBS and fly ash. Materials Today: Proceedings,
[3] Verma, Y., Shukla, A., & Kumar, A. (2023). Estimation of compressive strength of fly ash concrete using ML models. Scientific Reports, 13, 14565.
[4] Zhang, H., Liu, Q., & Wang, Z. (2023). Mechanical performance of GGBS blended concrete. Journal of Cleaner Production, 415, 137862.
[5] Ravi, V., Satpathy, B. K., & Debnath, S. (2024). Combined use of fly ash and GGBS in sustainable concrete. Springer Nature Applied Sciences, 6, 124.
[6] M. Ghanooni-Bagha, "Corrosion-induced reduction in compressive strength of self-compacting concretes containing mineral admixtures," Construction and Building Materials, 2016.
[7] ASTM C94, Standard Specification for Ready-Mixed Concrete, American Society for Testing and Materials (ASTM), 2017.
[8] M. Ghanooni-Bagha, "The effect of changes in carbon-dioxide concentrations on corrosion initiation of reinforced concrete structures," Construction and Building Materials, 2017.
[9] ASTM C150, Standard Specification for Portland Cement, American Society for Testing and Materials (ASTM), 2020.
[10] ASTM C33, Standard Specification for Concrete Aggregates, American Society for Testing and Materials (ASTM), 2018.
[11] M. Ghanooni-Bagha, "Optimal semi-active structural control with a wavelet-based cuckoo-search fuzzy logic controller," Construction and Building Materials, 2020.
[12] ASTM C989, Standard Specification for Slag Cement for Use in Concrete and Mortars, American Society for Testing and Materials (ASTM), 2020.
[13] ASTM C618, Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, American Society for Testing and Materials (ASTM), 2022.
[14] ASTM C511-19 – Standard Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes.
[15] ASTM C39/C39M-20 – Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens.
[16] ASTM C39/C39M-21 – Updated version of ASTM C39 for 2021.
[17] ASTM C39/C39M-23 – Latest version (2023) of the standard.
[18] ISIRI 302 – Standard of Iran: Compressive Strength Test Method for Concrete Cylinders.
[19] M. Ghanooni-Bagha, "Effect of transverse reinforcement corrosion on compressive strength reduction of stirrup-confined concrete: an experimental study," Construction and Building Materials, 2020.
[20] Kocaöz, S., & Arslan, M. E. (2023). Influence of slag and fly ash on mechanical and durability properties of concrete. Construction and Building Materials, 360, 129645.
[21] M. Ghanooni-Bagha, "Influence of chloride corrosion on tension capacity of rebars," Construction and Building Materials, 2021.
[22] M. Ghanooni-Bagha, "Influential factors on concrete carbonation: a review," Construction and Building Materials, 2023.
[23] Li, W., & Zhang, M. H. (2021). Combined effects of fly ash and ground granulated blast furnace slag on mechanical properties of concrete. Materials, 14(10), 2604.
[24] Zareei, S. A., Ameri, F., Dorostkar, F., & Ahmadi, M. (2020). Developing green concrete by using industrial waste: A case study of high-volume slag concrete. Journal of Cleaner Production, 253, 119938.
[25] Golewski, G. L. (2022). Green concrete based on quaternary binders with fly ash and slag: Compressive strength and microstructure. Journal of Building Engineering, 45, 103465.
[26] Falah, M. G., & Ramezanianpour, A. A. (2019). Mechanical performance of high-volume fly ash concrete under differentcuring conditions. Construction and Building Materials, 225, 745–755.
[27] M. Ghanooni-Bagha, "Probabilistic evaluation of chloride-induced corrosion effects on design parameters of RC beams," Construction and Building Materials, 2023.
[28] Lee, S., & Park, W. (2021). Effect of curing methods on the strength development of slag-fly ash blended concrete. Cement and Concrete Research, 147, 106530.
[29] Mousavi, S. M., & Ghafoori, N. (2018). Performance evaluation of fly ash-slag blended cementitious systems in terms of durability and strength. Materials and Structures, 51(3), 78.
[30] Ghanei, A., Nikbin, I. M., & Dehestani, M. (2020). Compressive strength prediction of eco-friendly concrete using ANN and regression methods. Journal of Materials in Civil Engineering, 32(4), 04020045.
[31] Rafieizonooz, M., Mirza, J., Salim, M. R., Hussin, M. W., & Khankhaje, E. (2017). Investigation of coal bottom ash and fly ash in concrete as replacement for natural sand and cement. Construction and Building Materials, 116, 15–24.
[32] Rashidian-Dezfouli, H., & Maleki, S. (2023). Optimizing the replacement level of fly ash in high-strength concrete using statistical methods. Materials Today: Proceedings, 72(2), 180–188