The Tuban-Babat-Lamongan-Gresik road section is one of the northern coast sections of Java, Indonesia that experienced road damage that have a low CBR value of around 1.7%-2.9%. In this study, the soil improvement method used is Water Fly Ash Cement Grouting which will be tested on a laboratory scale. Variations in addition to the quantity of grouting material are 3%, 5%, and 7% of dry weight in the test sample, water binder ratio (w/b) variations of 1, 1.5 and 2 with 3 binder composition variations, namely 90% Cement + 10% Fly Ash, 80% Cement + 20% Fly Ash, and 70% Cement + 30% Fly Ash. The selection of the use of Fly Ash in addition to utilizing waste from coal burning activities, relatively cheap prices and effectiveness which has been proven in previous studies.The results show that Water Fly Ash Cement Grouting can affect properties of the sample. The plasticity index which was originally 45.09% to 25.08% and the CBR value which was originally 0.14% to 1.92% at the quantity of grouting material 7% of the dry weight of the test sample, Water Binder ratio (w/b) 1 with a binder composition of 90% Cement + 10% Fly Ash.

Ahmed, B., Alim, A. & Sayeed, A. (2015). “Improvement of soil strength using cement and lime admixtures”. Journal of Earth Science, Vol. 2, No. 6, pp. 139-144.

Darmawan, W., Rachmansyah, A., & Zaika, Y. (2018). “Perubahan Stabilitas Tanah Akibat Penambahan Kapur,Semen, dan Fly Ash pada Tanah Lunak Proyek Tol Gempol-Pasuruan”. Jurnal Online Mahasiswa (JOM) Jurusan Teknik Sipil UB, Vol. 1, No. 2, Hal. : 993–1004.

Dissanayake, T. B. C. H., Senanayake, S. M. C. U., & Nasvi, M. C. M. (2017). “Comparison of the Stabilization Behavior of Fly Ash and Bottom Ash Treated Expansive Soil”. Journal of the Institution of Engineers, Vol. 50, No. 1, pp. 11.

Fadhil, W., & Mahmood, D. (2021). “Laboratory Study on the Effect of Water-Cement Ratio on Strength Characteristics of Jet Grouting”. Journal of Engineering, Vol. 27, No. 12, pp. 33-49.

Goh, Teck Shang, and Takashi, Osamu. (2014). “Laboratory Study On Grout Injection for Improving Subgrade of Airfield Pavements”. International Journal of Integrated Engineering, Vol. 6 No. 2, pp. 35-41.

Hangge, E. E., Bella, R. A., & Ullu, M. C. (2021). “Pemanfaatan Fly Ash Untuk Stabilisasi Tanah Dasar Lempung Ekspansif”. Jurnal Teknik Sipil, Vol. 10, No. 1, Hal. : 89-102.

Huri, A. D., Yulianto, K., R W, S. P., & Hardiyati, S. (2013). “Stabilisasi Tanah dengan Fly Ash dan Semen untuk Badan Jalan PLTU Asam-Asam”. Jurnal Karya Teknik Sipil, Vol. 2, No. 1, Hal. : 1-8.

Indrawati, E., Indarto, Soemitro, R. A. A., & Permadi, N. (2022). “Pengaruh Perkuatan Grouting Terhadap Beban Maksimum Yang Dapat Diterima Tanah Dasar Pada Ruas Jalan Lamongan - Gresik”. Jurnal Manajemen Aset Infrastruktur & Fasilitas, Vol. 6, No. 5, Hal. : 53–66.

Kusuma, R. I., Mina, E., & Rahman, T. (2013). “Stabilisasi Tanah Lempung Menggunakan Fly Ash Terhadap Nilai CBR”. Jurnal Fondasi, Vol. 2, No. 2, Hal. : 51-60.

Lembasi, M. K., Nugroho, S. A., & Fatnanta, F. (2022). “Perubahan Nilai Cbr Terhadap Penambahan Fly Ash Dan Bottom Ash Pada Tanah Lempung”. Jurnal Rekayasa Sipil, Vol. 16, No. 1, Hal. : 15–24.

Mehator, Edwin S., Satrya, T. R., Soemitro, R. A. A., & Ferdian, V. (2023). “Evaluasi Daya Dukung Tanah (CBR) Dan Lapisan Bawah Permukaan Pada Subgrade Yang Diperbaiki Dengan Metode Grouting Water Cement Di Ruas Jalan Nasional Tuban-Babat-Lamongan-Gresik”. Journal of Infrastructure and Facility Asset Management, Vol. 5.

Nikbakhtan, Babak, & Morteza, Osanloo. (2009). "Effect of grout pressure and grout flow on soil physical and mechanical properties in jet grouting operations". International Journal of Rock Mechanics and Mining Sciences Vol. 46, No. 3, pp. 498-505.

Rajak, T. K., & Pal, S. K. (2015). “CBR Values of Soil Mixed with Fly Ash and Lime”. International Journal of Engineering Research & Technology, Vol. 4 No. 2, pp. 763-768.

Setyono, E., Sunarto, & Wirasetiyo, K. (2018). “Pengaruh Bahan Tambah Fly Ash Terhadap Karakteristik Tanah Lempung Ekspansif Di Daerah Dringu Kabupaten Probolinggo”. Media Teknik Sipil, Vol. 16, No. 1, Hal. : 29-34.

Suprayitno, H., Soemitro, R. A. A. (2018). “Preliminary Reflexion on Basic Principle of Infrastructure Asset Management”. Jurnal Manajemen Aset Infrastruktur & Fasilitas, Vol. 2, No. 1, Hal. : 1–10.

Yuanita, I., Indarto, Soemitro, R. A. A., & Permadi, N. (2022). “Analisis Penurunan Tanah dengan Perkuatan Water Cement Grouting Pada Proyek Preservasi Ruas Tuban – Babat – Lamongan – Gresik”. Jurnal Manajemen Aset Infrastruktur & Fasilitas, Vol. 6, No. 3, Hal. : 21–36.

Zulnasri, A., Nugroho, S. A., & Fatnanta, F. (2021). “Perubahan Nilai Kuat Tekan Lempung Lunak Distabilisasi Dengan Kapur Dan Limbah Pembakaran Batubara”. Jurnal Rekayasa Sipil, Vol. 17, No. 1, Hal. : 24–35.