Abstract
This research investigates the impact of micro and macro steel fibers on the compressive strength of
geopolymer concrete (GPC). The study utilizes locally sourced materials, including river sand,
granite aggregates, fly ash, and ground granulated blast furnace slag (GGBS) in a 50:50 ratio as
alumino-silicate materials. Sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) were employed
as activators, with the addition of a superplasticizer (Conplast SP430) to enhance workability. Four
GPC mixes were analyzed: GPC without fibers, GPC1MI with 1% microfibers, GPC1MA with 1%
macro fibers, and GPC1MI1MA containing both micro and macro fibers. The study involved testing
cube and cylinder specimens after 28 days of curing. The results show that the addition of fibers
significantly improves compressive strength. The GPC1MI1MA mix achieved the highest compressive
strengths of 42.70 MPa for cubes and 37.40 MPa for cylinders, reflecting increases of 33% and 35%
respectively compared to the GPC mix without fibers. The findings suggest that the combined use of
micro and macro fibers in GPC enhances the material’s mechanical properties, making it suitable for
sustainable construction applications.
Keywords: Geopolymer concrete, micro steel fibers, macro steel fibers, compressive strength, tensile
strength, fiber reinforcement, load-bearing capacity

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1. Kishore GN, Gayathri B. Experimental study on rise husk ash & fly ash based geo-polymer concrete using M-sand. In: IOP Conference Series: Materials Science and Engineering. IOP Publishing; 2017.
2. Das SK, Mishra J, Mustakim SM. Rice husk ash as a potential source material for geopolymer concrete: A review. Int J Appl Eng Res. 2018;13(7):81–84.
3. Duxson P, Provis JL. Designing precursors for geopolymer cements. J Am Ceram Soc. 2008;91(12):3864–3869. doi: 10.1111/j.1551-2916.2008.02787.x.
4. Choo H. Compressive strength of one-part alkali activated fly ash using red mud as alkali supplier. Constr Build Mater. 2016;125:21–28. doi: 10.1016/j.conbuildmat.2016.08.015.
5. Shi H. Characterization and modification of the secondary copper smelting slag for smooth operation and slag valorization. 2017.
6. Nath P, Sarker PK. Flexural strength and elastic modulus of ambient-cured blended low-calcium fly ash geopolymer concrete. Constr Build Mater. 2017;130:22–31. doi: 10.1016/j.conbuildmat.2016.11.034.
7. Hajjaji W, Andrejkovičová S, Zanelli C, Alshaaer M, Dondi M, Labrincha JA, et al. Composition and technological properties of geopolymers based on metakaolin and red mud. Mater Des. 2013;52:648–654. doi: 10.1016/j.matdes.2013.05.058.
8. Cwirzen A. The effect of limestone on sodium hydroxide-activated metakaolin-based geopolymers. Constr Build Mater. 2014;66:53–62. doi: 10.1016/j.conbuildmat.2014.05.022.
9. Gunasekara C, Law DW, Setunge S, Sanjayan JG. Zeta potential, gel formation and compressive strength of low calcium fly ash geopolymers. Constr Build Mater. 2015;95:592–599. doi: 10.1016/j.conbuildmat.2015.07.175.
10. Wijaya SW, Hardjito D. Factors affecting the setting time of fly ash-based geopolymer. in Materials Science Forum. Trans Tech Publ; 2016.
11. Wattimena OK, Antoni A, Hardjito D. A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer. AIP Conf Proc. 2017;1887(1):020041. doi: 10.1063/1.5003524.
12. Antoni JS, Sugiarto A, Hardjito D. Effect of variability of Fly ash obtained from the same source on the characteristics of geopolymer. In: MATEC Web of Conferences 97, 01026 (2017), ETIC 2016, 2017.
13. Xin L. Effect of alkali-activator types on the dynamic compressive deformation behavior of geopolymer concrete. Materials Letters, 2014;124:310–312. doi: 10.1016/j.matlet.2014.03.102.
14. Błaszczyński TZ, Król MR. Alkaline Activator Impact on the Geopolymer Binders. in IOP Conference Series: Materials Science and Engineering. IOP Publishing; 2017.
15. Chamundeswari P, Rao VR. Effect of activator ratio on strength properties of geopolymer concrete. IJCIET. 2017;8(1):559–564.
16. Jiao Z. Effect of dosage of alkaline activator on the properties of alkali-activated slag pastes. Adv Mater Sci Eng. 2018; 2018(1):1–12. doi: 10.1155/2018/8407380.
17. Fang G. Workability and mechanical properties of alkali-activated fly ash-slag concrete cured at ambient temperature. Constr Build Mater. 2018;172:476–487. doi: 10.1016/j.conbuildmat.2018.04.008.
18. Nandeesh NC, Ghorpade VG. Strength and workability studies of geopolymer concrete with recycled coarse aggregate and quarry stone dust. Int J Adv Sci Technol. 2019;28(13):112–118.
19. Van Jaarsveld J, Van Deventer J, Lukey G. The characterisation of source materials in fly ash-based geopolymers. Mater Lett. 2003;57(7):1272–1280. doi: 10.1016/S0167-577X(02)00971-0.
20. Yang K-H, Song J-K. Workability loss and compressive strength development of cementless mortars activated by combination of sodium silicate and sodium hydroxide. J Mater Civ Eng. 2009;21(3)119–127. doi: 10.1061/(ASCE)0899-1561(2009)21:3(119).
21. Kumaravel S, Girija P, Vinoohini P. Effect of ambient curing in geopolymer concrete. Int J Appl Eng Res. 2015;10(51):46–48.
22. Hadi MN, Farhan NA, Sheikh MN. Design of geopolymer concrete with GGBFS at ambient curing condition using Taguchi method. Constr Build Mater. 2017;140:424–431. doi: 1016/j.conbuildmat.2017.02.131.
23. Ramamohana B, Gopinathan P, Chandrasekhar I. Engineering properties of GGBS & Fly ash synthesized geopolymer concrete at different environmental conditions by comparing with conventional concrete. Int J Recent Technol Eng. 2019;7(5S4).

Abstract
This research investigates the impact of micro and macro steel fibers on the compressive strength of
geopolymer concrete (GPC). The study utilizes locally sourced materials, including river sand,
granite aggregates, fly ash, and ground granulated blast furnace slag (GGBS) in a 50:50 ratio as
alumino-silicate materials. Sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) were employed
as activators, with the addition of a superplasticizer (Conplast SP430) to enhance workability. Four
GPC mixes were analyzed: GPC without fibers, GPC1MI with 1% microfibers, GPC1MA with 1%
macro fibers, and GPC1MI1MA containing both micro and macro fibers. The study involved testing
cube and cylinder specimens after 28 days of curing. The results show that the addition of fibers
significantly improves compressive strength. The GPC1MI1MA mix achieved the highest compressive
strengths of 42.70 MPa for cubes and 37.40 MPa for cylinders, reflecting increases of 33% and 35%
respectively compared to the GPC mix without fibers. The findings suggest that the combined use of
micro and macro fibers in GPC enhances the material’s mechanical properties, making it suitable for
sustainable construction applications.
Keywords: Geopolymer concrete, micro steel fibers, macro steel fibers, compressive strength, tensile
strength, fiber reinforcement, load-bearing capacity

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Kishore GN, Gayathri B. Experimental study on rise husk ash & fly ash based geo-polymer concrete using M-sand. In: IOP Conference Series: Materials Science and Engineering. IOP Publishing; 2017.
2. Das SK, Mishra J, Mustakim SM. Rice husk ash as a potential source material for geopolymer concrete: A review. Int J Appl Eng Res. 2018;13(7):81–84.
3. Duxson P, Provis JL. Designing precursors for geopolymer cements. J Am Ceram Soc. 2008;91(12):3864–3869. doi: 10.1111/j.1551-2916.2008.02787.x.
4. Choo H. Compressive strength of one-part alkali activated fly ash using red mud as alkali supplier. Constr Build Mater. 2016;125:21–28. doi: 10.1016/j.conbuildmat.2016.08.015.
5. Shi H. Characterization and modification of the secondary copper smelting slag for smooth operation and slag valorization. 2017.
6. Nath P, Sarker PK. Flexural strength and elastic modulus of ambient-cured blended low-calcium fly ash geopolymer concrete. Constr Build Mater. 2017;130:22–31. doi: 10.1016/j.conbuildmat.2016.11.034.
7. Hajjaji W, Andrejkovičová S, Zanelli C, Alshaaer M, Dondi M, Labrincha JA, et al. Composition and technological properties of geopolymers based on metakaolin and red mud. Mater Des. 2013;52:648–654. doi: 10.1016/j.matdes.2013.05.058.
8. Cwirzen A. The effect of limestone on sodium hydroxide-activated metakaolin-based geopolymers. Constr Build Mater. 2014;66:53–62. doi: 10.1016/j.conbuildmat.2014.05.022.
9. Gunasekara C, Law DW, Setunge S, Sanjayan JG. Zeta potential, gel formation and compressive strength of low calcium fly ash geopolymers. Constr Build Mater. 2015;95:592–599. doi: 10.1016/j.conbuildmat.2015.07.175.
10. Wijaya SW, Hardjito D. Factors affecting the setting time of fly ash-based geopolymer. in Materials Science Forum. Trans Tech Publ; 2016.
11. Wattimena OK, Antoni A, Hardjito D. A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer. AIP Conf Proc. 2017;1887(1):020041. doi: 10.1063/1.5003524.
12. Antoni JS, Sugiarto A, Hardjito D. Effect of variability of Fly ash obtained from the same source on the characteristics of geopolymer. In: MATEC Web of Conferences 97, 01026 (2017), ETIC 2016, 2017.
13. Xin L. Effect of alkali-activator types on the dynamic compressive deformation behavior of geopolymer concrete. Materials Letters, 2014;124:310–312. doi: 10.1016/j.matlet.2014.03.102.
14. Błaszczyński TZ, Król MR. Alkaline Activator Impact on the Geopolymer Binders. in IOP Conference Series: Materials Science and Engineering. IOP Publishing; 2017.
15. Chamundeswari P, Rao VR. Effect of activator ratio on strength properties of geopolymer concrete. IJCIET. 2017;8(1):559–564.
16. Jiao Z. Effect of dosage of alkaline activator on the properties of alkali-activated slag pastes. Adv Mater Sci Eng. 2018; 2018(1):1–12. doi: 10.1155/2018/8407380.
17. Fang G. Workability and mechanical properties of alkali-activated fly ash-slag concrete cured at ambient temperature. Constr Build Mater. 2018;172:476–487. doi: 10.1016/j.conbuildmat.2018.04.008.
18. Nandeesh NC, Ghorpade VG. Strength and workability studies of geopolymer concrete with recycled coarse aggregate and quarry stone dust. Int J Adv Sci Technol. 2019;28(13):112–118.
19. Van Jaarsveld J, Van Deventer J, Lukey G. The characterisation of source materials in fly ash-based geopolymers. Mater Lett. 2003;57(7):1272–1280. doi: 10.1016/S0167-577X(02)00971-0.
20. Yang K-H, Song J-K. Workability loss and compressive strength development of cementless mortars activated by combination of sodium silicate and sodium hydroxide. J Mater Civ Eng. 2009;21(3)119–127. doi: 10.1061/(ASCE)0899-1561(2009)21:3(119).
21. Kumaravel S, Girija P, Vinoohini P. Effect of ambient curing in geopolymer concrete. Int J Appl Eng Res. 2015;10(51):46–48.
22. Hadi MN, Farhan NA, Sheikh MN. Design of geopolymer concrete with GGBFS at ambient curing condition using Taguchi method. Constr Build Mater. 2017;140:424–431. doi: 1016/j.conbuildmat.2017.02.131.
23. Ramamohana B, Gopinathan P, Chandrasekhar I. Engineering properties of GGBS & Fly ash synthesized geopolymer concrete at different environmental conditions by comparing with conventional concrete. Int J Recent Technol Eng. 2019;7(5S4).