Optimization and Mechanical Performance of Alkali-Activated Bottom Ash and Polypropylene Fiber in Deep Mixing Columns

Abstract

Deep mixing columns (DMC) are one of the widely used soil improvement methods in cohesive and cohesionless soils. Cement and lime are predominantly used as conventional binders in DMC grout. Due to high CO2 emissions from conventional binders, the feasibility of using alkali-activated binders as DMC grout is being investigated. This study was conducted in three main stages. In the first stage, the proportions of bottom ash and activator (mixture of 10M NaOH and Na2SiO3) were optimized to achieve the highest UCS value using response surface methodology (RSM). In the second stage, the influence of polypropylene fiber content was examined in detail by incorporating varying amounts of fibers into the optimized binder-activator mixture to determine the optimal fiber content. Since DMC are fully buried, they are cured in the soil media. In this case, the soil temperature, which varies along the depth of the soil, also becomes the curing temperature of the DCM. Due to climate, soil condition and thermodynamic based parameters, curing temperature of the DMC varies throughout the soil depth. Therefore, in the third stage, the effect of curing temperature on the mechanical properties of the stabilized samples was evaluated under different temperatures. Results of the study revealed optimal UCS values with AAB content of 0.3-0.5 and activator content of 0.45-0.5. Polypropylene fiber reinforcement further improved strength, reaching an optimum at 1.50-1.75% content. Curing temperature played a significant role, with UCS and modulus of elasticity increasing up to 30 °C, indicating the importance of considering environmental factors in DMC design. These findings suggest that the optimized mixture has the potential to replace conventional cement-based binders in DMCs, offering a more sustainable solution with lower carbon emissions. Furthermore, the observed influence of curing temperature highlights the need to account for subsurface thermal variations when designing DMCs, as these factors significantly affect strength gain and long-term performance.

Keywords

• Alkali activated binder
• Curing temperature
• Deep mixing column
• Optimization
• Polypropylene fiber

References

1. [1]. Kitazume M, Terashi M. The Deep Mixing Method; CRS Press: Taylor & Francis Group, Tokio, Japan; 2013.
2. [2]. Ekmen AB, Algın HM , Özen M. 2020. Strength and stiffness optimisation of fly ash-admixed DCM columns constructed in clayey silty sand. Transportation Geotechnics; 24 : 100364, https://doi.org/10.1016/j.trgeo.2020.100364.
3. [3]. Yang S, Zhang D, Tamura S, Hongjiang L, Anhui W. 2025. Investigation of seismic performance of group piles with different cement soil improvements in liquefiable sands: shaking table test. International Journal of Civil Engineering https://doi.org/10.1007/s40999-025-01121-0
4. [4]. Amer AA, El-Hoseny S. 2017. Properties and performance of metakaolin pozzolanic cement pastes. Journal of Thermal Analysis and Calorimetry;129 : 33–44. https://doi.org/10.1007/s10973-017-6087-9.
5. [5]. Öksüzer N. 2023. The effect of calcination on alkali-activated lightweight geopolymers produced with volcanic tuffs. Journal of the Australian Ceramic Society; 59:1053-1063 https://doi.org/10.1007/s41779-023-00896-6.
6. [6]. Yılmaz F, Kuvat A, Kamiloğlu HA. 2023. Optimizing and investigating durability performance of sandy soils stabilized with alkali activated waste tuff-fly ash mixtures. Sādhanā; 48:185. https://doi.org/10.1007/s12046-023-02250-9.
7. [7]. Kumar A, Saravanan TJ, Bisht K, Kabeer K. 2021. A review on the utilization of red mud for the production of geopolymer and alkali activated concrete. Construction and Building Materials; 302, 124170. https://doi.org/10.1016/j.conbuildmat.2021.124170.
8. [8]. Alves BIA, Marvila MT, Linhares Júnior JAT, Vieira CMF, Alexandre J, de Azevedo ARG. 2024. Alkaline activation of binders: a comparative study. Materials (Basel);17 : 667. https://doi.org/10.3390/ma17030667.

9. [9]. Nouhi S, Khaksar Najafi E, Zanganeh Ranjbar P, Payan M, Jamshidi Chenari R. 2024. Geotechnical performance of alkali-activated uncalcined clayey soils with hydroxide and aluminate-based activators. Journal of Materials in Civil Engineering;36. https://doi.org/10.1061/JMCEE7.MTENG-16746.
10. [10]. Hamid Abed M, Hamid Abed F, Alireza Zareei S, Sabbar Abbas I, Canakci H, Kurdi NH, et al 2024. Experimental feasibility study of using eco- and user-friendly mechanochemically activated slag/fly ash geopolymer for soil stabilization. Clean Mater;11:100226. https://doi.org/10.1016/j.clema.2024.100226.
11. [11]. Martins Lima B, Bruschi GJ, Festugato L, Consoli NC. 2024. Mechanical behavior of a granular soil stabilized with alkali-activated waste. Journal of Materials in Civil Engineering; 36. https://doi.org/10.1061/JMCEE7.MTENG-15641.
12. [12]. Komaei A, Saeedi A. 2025. Pumicite-based geopolymer optimization for sustainable soil stabilization. Journal of Materials in Civil Engineering, 37:6, 04025141. https://doi.org/10.1061/JMCEE7.MTENG-19308.
13. [13]. Hamed E, Demiröz A. 2024. Optimization of geotechnical characteristics of clayey soils using fly ash and granulated blast furnace slag-based geopolymer. Construction and Building Materials ;441:137488. https://doi.org/10.1016/j.conbuildmat.2024.137488.
14. [14]. Juengsuwattananon K, Winnefeld F, Chindaprasirt P, Pimraksa K. 2019. Correlation between initial SiO2/Al2O3, Na2O/Al2O3, Na2O/SiO2 and H2O/Na2O ratios on phase and microstructure of reaction products of metakaolin-rice husk ash geopolymer. Construction and Building Materials;226:406–17. https://doi.org/10.1016/j.conbuildmat.2019.07.146.
15. [15]. Kamiloğlu HA, Kurucu K, Akbaş D. 2024. Investigating the effect of polypropylene fiber on mechanical features of a geopolymer-stabilized silty soil. KSCE Journal of Civil Engineering;28:628–43. https://doi.org/10.1007/s12205-023-0488-z.
16. [16]. Shu Y, Song Y, Fan, H, Wang D, Lu , Huang Y, Zhao C, Chen L, Song, X. 2024. Fiber-reinforced microbially induced carbonate precipitation (MICP) for enhancing soil stability: mechanisms, effects, and future prospects. Journal of Building Engineering; 94:109955. https://doi.org/10.1016/j.jobe.2024.109955
17. [17]. Al-Dossary AAS, Awed AM, Gabr AR, Fattah MY, El-Badawy SM. 2023. Performance enhancement of road base material using calcium carbide residue and sulfonic acid dilution as a geopolymer stabilizer. Construction and Building Materials; 364:129959. https://doi.org/10.1016/j.conbuildmat.2022.129959.
18. [18]. Harmal A, Khouchani O, El-Korchi T, Tao M, Walker HW. 2023. Bioinspired brick-and-mortar geopolymer composites with ultra-high toughness. Cement and Concrete Composites;137:104944. https://doi.org/10.1016/j.cemconcomp.2023.104944.
19. [19]. Sukontasukkul P, Jamsawang P. 2012. Use of steel and polypropylene fibers to improve flexural performance of deep soil–cement column. Construction and Building Materials; 29:201–205. https://doi.org/10.1016/j.conbuildmat.2011.10.040.
20. [20]. Ekmen AB, Algın HM. 2023. Optimization of fiber-reinforced deep cement-fly ash mixing column materials. Revista de la Construcción. Journal of Construction; 22:3:707-728. https://doi.org/10.7764/RDLC.22.3.707.
21. [21]. Avcı Y, Ekmen AB. 2023. Artificial intelligence assisted optimization of rammed aggregate pier supported raft foundation systems based on parametric three-dimensional finite element analysis. Structures; 56:105031. https://doi.org/10.1016/j.istruc.2023.105031.
22. [22]. Zangeneh N, Azizian A, Lye L, Popescu R. Application of response surface methodology in numerical geotechnical analysis. 55th Can. Soc. Geotech. Conf., Hamilton, Ontario, Canada: 2002.
23. [23]. Deshpande TD, Kumar S, Begum G, Basha SAK, Rao BH. 2021. Analysis of railway embankment supported with geosynthetic-encased stone columns in soft clays: a case study. International Journal of Geosynthetics and Ground Engineering; 7:43. https://doi.org/10.1007/s40891-021-00288-5.
24. [24]. Yao K, Yao Z, Song X, Zhang X, Hu J, Pan X. 2016. Settlement evaluation of soft ground reinforced by deep mixed columns. International Journal of Pavement Research and Technology;9:460–5. https://doi.org/10.1016/j.ijprt.2016.07.003.
25. [25]. Phutthananon C, Jongpradist P, Wonglert A, Kandavorawong K, Sanboonsiri S, Jamsawang P. 2023. Field and 3D numerical ınvestigations of the performances of stiffened deep cement mixing column-supported embankments built on soft soil. Arabian Journal for Science and Engineering; 48:5139–69. https://doi.org/10.1007/s13369-022-07322-2.
26. [26]. Voottipruex P, Bergado DT, Suksawat T, Jamsawang P, Cheang W. 2011. Behavior and simulation of deep cement mixing (DCM) and stiffened deep cement mixing (SDCM) piles under full scale loading. Soils and Foundations; 51 : 307–320. https://doi.org/10.3208/sandf.51.307.
27. [27]. Chen S, Guan Y, Dai J, Zhao W. 2023. Field experimental and numerical studies on performance of concrete–cored gravel column-supported embankments. International Journal of Geomechanics; 23. https://doi.org/10.1061/IJGNAI.GMENG-8263.
28. [28]. Bhavita Chowdary V, Ramanamurty V, Pillai RJ. 2021. Experimental evaluation of strength and durability characteristics of geopolymer stabilised soft soil for deep mixing applications. Innovative Infrastructure Solutions; 6:40. https://doi.org/10.1007/s41062-020-00407-7.
29. [29]. Jastrzębska M. 2025. Use of alternative materials in sustainable geotechnics: state of world knowledge and some examples from Poland. Applied Sciences, 15, 6: 3352. https://doi.org/10.3390/app15063352.
30. [30]. Sabziparvar A, Khoshhal Jahromi F. 2022. Evaluating the most effective climatic parameters affecting the monthly mean soil temperature estimates using the PLS method. Arabian Journal of Geosciences;15:1044. https://doi.org/10.1007/s12517-022-10297-x.
31. [31]. Bruce M, Berg R, Collin J, Filz G, Terashi M, Yang DS. Federal Highway Administration design manual: Deep mixing for embankment and foundation support. United States Federal Highway Administration Offices of Research & Development 2013.
32. [32]. Shi X, Zhang C, Liang Y, Luo J, Wang X, Feng Y, Li Y, Wang Q Consistency Abomohra AE-F. Life cycle assessment and impact correlation analysis of fy ash geopolymer concrete. Materials (Basel), 14(23):7375 2021.
33. [33]. Davidovits J. False values on CO2 emission for geopolymer cement/concrete published in scientific papers. Geopolymer Institute. Library.https://www.geopolymer.org/library/technicalpapers/falseCO2-values-published-inscientific-papers/. Accessed 15 May 2024
34. [34]. Setiawan AA, Hardjasaputra H, Soegiarso R. 2023. Embodied carbon dioxide of fy ash based geopolymer concrete. e. IOP Conf Ser Earth. Environ. Sci, 1195(1):012, 1. https://doi.org/10.1088/1755-1315/1195/1/012031
35. [35]. Farouk A, Shahien MM. 2013. Ground improvement using soil– cement columns: experimental investigation . Alexandria Engineering Jpurnal. 52(4):733–740. https://doi.org/10.1016/j.aej.2013.08.009