Tanah merupakan bahan dasar yang sangat berpengaruh dalam struktur atau konstruksi suatu bangunan sipil, maka dari itu diperlukan tanah yang memiliki karakteristik serta daya dukung yang baik. tanah gambut sering menimbulkan masalah pada bangunan-bangunan yang ada diatasnya. salah satu alternatif yang digunakan untuk memperbaiki kualitas tanah ialah dengan stabilisasi. stabilisasi merupakan usaha dalam memperbaiki sifat fisis dan mekanis tanah, yaitu dengan penambahan campuran stabilizer berupa fly ash dan kapur. tujuan penelitian ini untuk mengetahui nilai sifat fisis dan kuat tekan bebas tanah gambut sebelum dan sesudah distabilisasi dengan fly ash dan kapur serta pengaruh variasi waktu pemeraman terhadap nilai sifat fisis dan kuat tekan, penambahan stabilizer (fly ash dan kapur) sebesar 20%, 40%, dan 60% dengan waktu pemeraman selama 20 hari, 30 hari, 40 hari, dan 60 hari. tanah diambil dari teluk selimau, kabupaten bulungan, kalimantan utara. pengujian sifat fisis yang dilakukan yaitu kadar abu, kadar organik, kadar serat, kadar air, kadar ph, berat volume, analisa saringan, dan specific gravity. sedangkan pengujian untuk sifat mekanisnya menggunakan uji kuat tekan bebas. dalam proses penelitian ini didapatkan nilai kuat tekan bebas tertinggi pada persentase campuran stabilizer (fly ash dan kapur) 60% masa peram hari ke-60 dengan nilai sebesar 0,165 kg/cm2. kata kunci : tanah, gambut, fly ash, kapur, kuat tekan.

Soil is a basic material that is very influential the structure or construction of a civil building, so it is necessary that the soil has good characteristic and bearing capacity. peat soil often causes problems for the building constructed above it. one of the alternatives used to improve soil quality is stabilization. stabilization is an effort to improve the physical and mechanical properties of soil, namely by adding a mixture of stabilizer in the form of fly ash and lime. this study aims to determine the value of physical properties and unconfined compressive strength of peat soil before and after stabilization with fly ash and lime and the effect of variation in curring time on the value of physical properties and unconfined compressive strength, the addition of stabilizer (fly ash and lime) of 20%, 40%, and 60% with curring time for 20 days, 30 days, 40 days, and 60 day. the soil sample was taken from teluk selimau, bulungan regency, north kalimantan. physical properties test carried out were ash content, organic content, fiber content, moisture content, ph content, unit of weight, sieve analysis, and specific gravity. meanwhile, the mechanical properties test used an unconfined compressive strength test. in this research process, the higest unconfined compressive strength value was obtained at the percentage of the stabilizer mixture (fly ash and lime) of 60% on the 60 days of soaking period with a value of 0.165 kg/cm2. keywords : soil, peat, fly ash, lime, compressive strength.