The Effect of Stabilizing the California Bearing Ratio (CBR) and Unconfined Compression Strength (UCS) of Clay Soil Using Fly Ash and Slacked Lime
Keywords:
Clay Soil, CBR, Fly Ash, Hydrated Lime, Soil Stabilization.Abstract
Clay soil is frequently encountered in road and building construction, yet its low bearing capacity, high plasticity, and sensitivity to moisture variations can limit its suitability as a subgrade material. This study aims to characterize clay soil from the Kaligawe area of Semarang and evaluate the effects of fly ash, hydrated lime, and their combination on California Bearing Ratio (CBR) and Unconfined Compression Strength (UCS). An experimental laboratory approach was employed using untreated soil and stabilized specimens with additive contents of 2%, 4%, 6%, 8%, 10%, 12%, 15%, and 20% based on dry soil weight. The testing program comprised Atterberg limits, Standard Proctor compaction, soaked and unsoaked CBR, and UCS tests. The untreated soil exhibited a Liquid Limit of 65.375%, Plastic Limit of 27.611%, Plasticity Index of 37.764%, unsoaked CBR of 4.80%, soaked CBR of 3.10%, and UCS of 0.867 kg/cm². Fly ash achieved optimum CBR values at 15%, reaching 12.20% unsoaked and 8.80% soaked, whereas hydrated lime achieved 19.60% unsoaked and 17.00% soaked at 10%. The combined treatment produced the highest unsoaked CBR of 21.20% and UCS of 2.284 kg/cm² at 10% fly ash + 10% hydrated lime. UCS values for fly ash and hydrated lime individually reached 1.725 and 2.198 kg/cm², respectively. The findings demonstrate that combined stabilization effectively enhances clay performance, with 10% + 10% identified as the optimum composition.
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References
Abdelbaset, A. M., Katunský, D., Zeleňáková, M., & El-Feky, M. H. (2024). Mechanical properties stabilization of low plasticity Kaolin soil using fly ash and hydrated lime. Case Studies in Construction Materials, 21, e03662. https://doi.org/10.1016/j.cscm.2024.e03662
Abdurrahim, Abdurrahim (2023) Stabilisasi Tanah Lempung Memakai Kapur Padam Ditinjau dari CBR Laboratorium. Diploma thesis, Universitas Islam Kalimantan MAB. https://eprints.uniska-bjm.ac.id/14811/
Ahmed, S. T., Kabir, M. U., Zahid, C. Z. B., Tareque, T., & Mirmotalebi, S. (2024). Improvement of subgrade California Bearing Ratio (CBR) using recycled concrete aggregate and fly ash. Hybrid Advances, 5, 100153. https://doi.org/10.1016/j.hybadv.2024.100153
Ali, H. F. H., & Mohammed, A. S. (2026). A Unique Framework for UCS and CBR Prediction: The Role of Chemical Oxides in Stabilizing Fine-Grained Soils with Fly Ash and Cement. International Journal of Pavement Research and Technology, 1-31. https://doi.org/10.1007/s42947-026-00723-8
American Concrete Institute. (2019). Use of fly ash in concrete (ACI 232.2R). American Concrete Institute.
ASTM International. (2020). ASTM D2166/D2166M: Standard test method for unconfined compressive strength of cohesive soil. ASTM International.
ASTM International. (2021). ASTM D1883/D1883M: Standard test method for California bearing ratio (CBR) of laboratory-compacted soils. ASTM International.
ASTM International. (2022). ASTM D3282: Standard practice for classification of soils and soil-aggregate mixtures for highway construction purposes. ASTM International.
Badan Standardisasi Nasional. (2012a). SNI 1744:2012: Metode Uji CBR Laboratorium. Badan Standardisasi Nasional.
Badan Standardisasi Nasional. (2012b). SNI 3638:2012: Metode Uji Kuat Tekan-Bebas Tanah Kohesif. Badan Standardisasi Nasional.
Bowles, J. E. (1989). Sifat-Sifat Fisis dan Geoteknis Tanah. Erlangga.
Das, B. M. (2021). Principles of geotechnical engineering (10th ed.). Cengage Learning.
Hardiyatmo, H. C. (2002). Mekanika tanah I. Gadjah Mada University Press.
Hardiyatmo, H. C. (2020). Stabilisasi tanah untuk perkerasan jalan. Gadjah Mada University Press.
Harwadi, F., Hasrullah, H., & Singal, R. Z. (2022). Pengaruh Nilai CBR Tanah Bermasalah Yang Distabilisasi Dengan Fly ash di Wilayah Perbatasan Provinsi Kaltara. Borneo Engineering: Jurnal Teknik Sipil, 6(3), 197-206. https://doi.org/10.35334/be.v1i1.3206
Little, D. N., et al. (2021). Lime stabilization of fine-grained soils. National Lime Association.
Miswar, M., Syaifuddin, S., & Amani, N. (2017). Stabilisasi Tanah Lempung Menggunakan Semen Dan Kapur Untuk Meningkatkan Daya Dukung CBR Tanah. Portal: Jurnal Teknik Sipil, 9(2). http://dx.doi.org/10.30811/portal.v9i2.615
Muhmed, A., Mohamed, M., & Khan, A. (2022). The impact of moisture and clay content on the unconfined compressive strength of lime treated highly reactive clays. Geotechnical and Geological Engineering, 40(12), 5869-5893. https://doi.org/10.1007/s10706-022-02255-x
Nugroho, S. A., Al Ridho, M. F., & Fatnanta, F. (2022). Pengaruh Abu Sekam Kayu Pada Nilai Unconfined Compression Strength Lempung Plastisitas Tinggi Terstabilisasi Semen Kapur. Teras Jurnal : Jurnal Teknik Sipil, 12(1), 141–152. https://doi.org/10.29103/tj.v12i1.688
Salehi, M., Bayat, M., Saadat, M., & Nasri, M. (2023). Prediction of unconfined compressive strength and California bearing capacity of cement-or lime-pozzolan-stabilised soil admixed with crushed stone waste. Geomechanics and Geoengineering, 18(4), 272-283. https://doi.org/10.1080/17486025.2022.2040606
Setiyono, B. (2022). Pengaruh stabilisasi tanah lempung menggunakan kapur tohor dan fly ash terhadap parameter nilai CBR (California Bearing Ratio) dan swelling [Skripsi, Universitas Islam Indonesia]. DSpace UII. https://dspace.uii.ac.id/handle/123456789/40562
Sharif, S., Ali, K., Khan, M. A., & Sajid, M. (2025). Cost implication of utilizing fly ash and lime for stabilizing clayey soil as subgrade for construction of pavement. Discover Civil Engineering, 2(1), 160. https://doi.org/10.1007/s44290-025-00329-2
Utami, E. T., Tambunan, H. F., & Simanjuntak, I. R. U. (2021). Stabilisasi Tanah Lempung Menggunakan Abu Terbang (Fly Ash) Sebagai Upaya Peningkatan Daya Dukung Tanah Dasar (Studi Kasus: Karang Anyar, Lampung Selatan). Fondasi: Jurnal Teknik Sipil, 10(1), 17-23. https://dx.doi.org/10.36055/fondasi.v10i1.10610
Wardani, M. K., Utami, G. S., Syafiarti, A. I. D., Lestari, L. L., & Fikri, M. A. (2026). Peningkatan Nilai CBR Tanah Lempung Ekspansif Lakarsantri Surabaya Melalui Variasi Kapur Padam dan Waktu Pemeraman. Jurnal Teknik Sipil Institut Teknologi Padang, 13(1), 76-83. https://doi.org/10.21063/jts.2026.V1301.076-83
Wesley, L. D. (1994). Mekanika tanah. Badan Penerbit Pekerjaan Umum.
Yacub, M. A., Indriani, A. M., & Utomo, G. (2025). Pengaruh Penggunaan Fly Ash Sebagai Bahan Stabilisasi Tanah Lempung Organik Terhadap Nilai Unconfined Compression Strength. Konferensi Nasional Teknik Sipil (KoNTeks), 1(1). https://doi.org/10.62603/ze6p1c55
Yulianti, D., Firda, A., Djohan, B., & Syahrul Fuad, I. (2023). Stabilitas Tanah Lempung Menggunakan Kapur dan Fly Ash dengan Pengujian CBR. Jurnal Teknik Sipil LATERAL, 1(2), 47–53. https://doi.org/10.52333/lateral.v1i2.411
