Ambient-Cured Foamed Geopolymer Blocks: Mix Optimization and Microstructural Performance
Downloads
This study aims to develop sustainable, ambient-cured lightweight foamed geopolymer blocks utilizing fly ash (FA) and sugarcane bagasse ash (SCBA) to reduce energy consumption in masonry unit production. A comprehensive parametric investigation was conducted on six key mix variables: ordinary Portland cement (OPC) addition, SCBA replacement, foam dosage, liquid-to-binder ratio, alkaline activator ratio, and sand-to-binder ratio. The engineering properties, specifically 7-day compressive strength and bulk density, were evaluated and supported by microstructural characterization using XRD and SEM. The experimental results revealed that the optimum mix comprising a binder of 90% FA and 10% OPC, 10% SCBA replacement, 3% pre-formed foam, a liquid-to-binder ratio of 0.7, a sodium silicate-to-sodium hydroxide ratio of 1.0, and a sand-to-binder ratio of 2.25 was formulated and achieved a lightweight classification (≤ 1,800 kg/m³) with a compressive strength of 9.05 MPa. The significance of this study lies in establishing an optimum mix design that enables the utilization of multiple agro-industrial wastes in structural blocks without the need for energy-intensive thermal curing, thereby offering a viable and eco-friendly alternative for the construction industry.
Downloads
[1] Andrew, R. M. (2018). Global CO2 emissions from cement production. Earth System Science Data, 10(1), 195–217. doi:10.5194/essd-10-195-2018.
[2] Barbhuiya, S., Kanavaris, F., Das, B. B., & Idrees, M. (2024). Decarbonising cement and concrete production: Strategies, challenges and pathways for sustainable development. Journal of Building Engineering, 86, 108861. doi:10.1016/j.jobe.2024.108861.
[3] Volaity, S. S., Aylas-Paredes, B. K., Han, T., Huang, J., Sridhar, S., Sant, G., Kumar, A., & Neithalath, N. (2025). Towards decarbonization of cement industry: a critical review of electrification technologies for sustainable cement production. NPJ Materials Sustainability, 3(1), 23. doi:10.1038/s44296-025-00068-6.
[4] Davidovits, J. (1991). Geopolymers - Inorganic polymeric new materials. Journal of Thermal Analysis, 37(8), 1633–1656. doi:10.1007/BF01912193.
[5] Provis, J. L., & Bernal, S. A. (2014). Geopolymers and related alkali-activated materials. Annual Review of Materials Research, 44, 299–327. doi:10.1146/annurev-matsci-070813-113515.
[6] Provis, J. L. (2018). Alkali-activated materials. Cement and Concrete Research, 114, 40–48. doi:10.1016/j.cemconres.2017.02.009.
[7] Castillo, H., Collado, H., Droguett, T., Sánchez, S., Vesely, M., Garrido, P., & Palma, S. (2021). Factors affecting the compressive strength of geopolymers: A review. Minerals, 11(12), 1317. doi:10.3390/min11121317.
[8] Ahmed, H. U., Mohammed, A. A., Rafiq, S., Mohammed, A. S., Mosavi, A., Sor, N. H., & Qaidi, S. M. (2021). Compressive strength of sustainable geopolymer concrete composites: a state-of-the-art review. Sustainability, 13(24), 13502. doi:10.3390/su132413502.
[9] Cordeiro, G. C., Toledo Filho, R. D., Tavares, L. M., & Fairbairn, E. M. R. (2008). Pozzolanic activity and filler effect of sugar cane bagasse ash in Portland cement and lime mortars. Cement and Concrete Composites, 30(5), 410–418. doi:10.1016/j.cemconcomp.2008.01.001.
[10] Maldonado-García, M. A., Hernández-Toledo, U. I., Montes-García, P., & Valdez-Tamez, P. L. (2018). The influence of untreated sugarcane bagasse ash on the microstructural and mechanical properties of mortars. Materiales de Construccion, 68(329), 148. doi:10.3989/mc.2018.13716.
[11] Thomas, B. S., Yang, J., Bahurudeen, A., Abdalla, J. A., Hawileh, R. A., Hamada, H. M., Nazar, S., Jittin, V., & Ashish, D. K. (2021). Sugarcane bagasse ash as supplementary cementitious material in concrete – a review. Materials Today Sustainability, 15, 100086. doi:10.1016/j.mtsust.2021.100086.
[12] Rihan, M. A. M., Alahmari, T. S., Onchiri, R. O., Gathimba, N., & Sabuni, B. (2024). Impact of Alkaline Concentration on the Mechanical Properties of Geopolymer Concrete Made up of Fly Ash and Sugarcane Bagasse Ash. Sustainability (Switzerland), 16(7), 2841. doi:10.3390/su16072841.
[13] Muradyan, N., Arzumanyan, A., Kalantaryan, M., Khachatryan, K., Zendri, E., & Arzumanyan, A. (2025). Geopolymer Mortars from Tuff Waste: A Circular Approach. Civil Engineering Journal, 11(10), 4092–4107. doi:10.28991/CEJ-2025-011-10-07.
[14] Wardhono, A. (2018). The Effect of Sodium Hydroxide Molarity on Strength Development of Non-Cement Class C Fly Ash Geopolymer Mortar. Journal of Physics: Conference Series, 947(1), 12001. doi:10.1088/1742-6596/947/1/012001.
[15] Ramamurthy, K., Kunhanandan Nambiar, E. K., & Indu Siva Ranjani, G. (2009). A classification of studies on properties of foam concrete. Cement and Concrete Composites, 31(6), 388–396. doi:10.1016/j.cemconcomp.2009.04.006.
[16] Othman, R., Jaya, R. P., Muthusamy, K., Sulaiman, M., Duraisamy, Y., Abdullah, M. M. A. B., Przybył, A., Sochacki, W., Skrzypczak, T., Vizureanu, P., & Sandu, A. V. (2021). Relation between density and compressive strength of foamed concrete. Materials, 14(11), 2967. doi:10.3390/ma14112967.
[17] Amran, M., Fediuk, R., Vatin, N., Lee, Y. H., Murali, G., Ozbakkaloglu, T., Klyuev, S., & Alabduljabber, H. (2020). Fibre-reinforced foamed concretes: A review. Materials, 13(19), 1–36. doi:10.3390/ma13194323.
[18] Rashad, A. M., Mosleh, Y. A., & Mokhtar, M. M. (2024). Thermal insulation and durability of alkali-activated lightweight slag mortar modified with silica fume and fly ash. Construction and Building Materials, 411, 134255. doi:10.1016/j.conbuildmat.2023.134255.
[19] Morsy, M. S., Alsayed, S. H., Al-Salloum, Y., & Almusallam, T. (2014). Effect of Sodium Silicate to Sodium Hydroxide Ratios on Strength and Microstructure of Fly Ash Geopolymer Binder. Arabian Journal for Science and Engineering, 39(6), 4333–4339. doi:10.1007/s13369-014-1093-8.
[20] Wardhono, A., Risdianto, Y., Sabariman, B., Hidajati, N. W., & Andajani, N. (2023). The Effect of Sodium Silicate to NaOH Ratio on Strength Development of Fly Ash Geopolymer Mortar in Marine Environment. E3S Web of Conferences, 445, 1005. doi:10.1051/e3sconf/202344501005.
[21] Verma, M., & Dev, N. (2022). Effect of Liquid to Binder Ratio and Curing Temperature on the Engineering Properties of the Geopolymer Concrete. Silicon, 14(4), 1743–1757. doi:10.1007/s12633-021-00985-w.
[22] Naghizadeh, A., & Ekolu, S. O. (2018). Effect of mix parameters on strength of geopolymer mortars-experimental study. 6th International Conference on Durability of Concrete Structures, ICDCS 2018, 18-20 July, 2018, Leeds, United Kingdom.
[23] Rojas-Duque, O., Espinosa, L. M., Robayo-Salazar, R. A., & de Gutiérrez, R. M. (2020). Alkali-activated hybrid concrete based on fly ash and its application in the production of high-class structural blocks. Crystals, 10(10), 946. doi:10.3390/cryst10100946.
[24] Nguyễn, P. H., Nguyễn, H. H., Lương, Q.-H., Kim, Y., & Lee, B. Y. (2026). Ambient Temperature Curing Stimulated One-Part Engineered Geopolymer Composites with Extremely High Ductility and Low Thermal Conductivity. Journal of Materials in Civil Engineering, 38(4). doi:10.1061/jmcee7.mteng-22099.
[25] Le, D. H., Phan, V. T. A., & Vo, V. T. (2026). Fly ash–sugarcane bagasse ash geopolymer materials: curing optimization and evaluation of strength, shrinkage, and sulfate resistance. Innovative Infrastructure Solutions, 11(5), 261. doi:10.1007/s41062-026-02667-1.
[26] Vo, V. T., Le, D. H., & Phan, V. T. A. (2026). Optimisation of alkaline solution for fly ash-sugarcane bagasse ash geopolymer mortars: effects on strength, durability, and microstructure. European Journal of Environmental and Civil Engineering, 30(1), 2604297. doi:10.1080/19648189.2025.2604297.
[27] Lương, Q. H., Nguyễn, H. H., Nguyễn, P. H., Park, S. E., Kim, Y., & Lee, B. Y. (2025). Achieving ultra-ductility exceeding 13 % and cost efficiency with rubberized alkali-activated slag-based cement-free composites. Developments in the Built Environment, 22, 100677. doi:10.1016/j.dibe.2025.100677.
[28] Pratap, B., Kumar, S., Gupta, K. K., Reddy, N. G., Rashid, A., Asaithambi, P., & Karuppannan, S. (2026). Mechanical properties analysis of geopolymer concrete based on the sugarcane bagasse ash using machine learning. Scientific Reports, 16(1), 14485. doi:10.1038/s41598-026-44848-z.
[29] ASTM C150/C150M-24. (2021). Standard Specification for Portland Cement. ASTM International, Pennsylvania, United States. doi:10.1520/C0150_C0150M-24.
[30] ASTM C618-23. (2010). Standard Specification for Coal Ash and Raw or Calcined Natural Pozzolan for Use in Concrete. ASTM International, Pennsylvania, United States. doi:10.1520/C0618-23.
[31] Cordeiro, G. C., Toledo Filho, R. D., Tavares, L. M., & Fairbairn, E. de M. R. (2009). Ultrafine grinding of sugar cane bagasse ash for application as pozzolanic admixture in concrete. Cement and Concrete Research, 39(2), 110–115. doi:10.1016/j.cemconres.2008.11.005.
[32] Somna, K., Jaturapitakkul, C., Kajitvichyanukul, P., & Chindaprasirt, P. (2011). NaOH-activated ground fly ash geopolymer cured at ambient temperature. Fuel, 90(6), 2118–2124. doi:10.1016/j.fuel.2011.01.018.
[33] Wongkvanklom, A., Posi, P., Kampala, A., Kaewngao, T., & Chindaprasirt, P. (2021). Beneficial utilization of recycled asphaltic concrete aggregate in high calcium fly ash geopolymer concrete. Case Studies in Construction Materials, 15, 615. doi:10.1016/j.cscm.2021.e00615.
[34] Rukzon, S., & Chindaprasirt, P. (2012). Utilization of bagasse ash in high-strength concrete. Materials & Design, 34, 45–50. doi:10.1016/j.matdes.2011.07.045.
[35] Wongkvanklom, A., Posi, P., Kasemsiri, P., Sata, V., Cao, T., & Chindaprasirt, P. (2021). Strength, thermal conductivity and sound absorption of cellular lightweight high calcium fly ash geopolymer concrete. Engineering and Applied Science Research, 48(4), 487-496.
[36] ASTM C109/C109M-21. (2024). Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube Specimens). ASTM International, Pennsylvania, United States. doi:10.1520/C0109_C0109M-21.
[37] ASTM C138/C138M-24a. (2024). Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete. ASTM International, Pennsylvania, United States. doi:10.1520/C0138_C0138M-24A.
- Authors retain all copyrights. It is noticeable that authors will not be forced to sign any copyright transfer agreements.
- This work (including HTML and PDF Files) is licensed under a Creative Commons Attribution 4.0 International License.
