Tanah lempung lunak adalah salah satu jenis tanah dasar yang sering menyebabkan masalah dalam berbagai jenis konstruksi karena daya dukungnya rendah dan kepekaan terhadap perubahan kadar air cukup tinggi. Oleh karena itu sifat fisis dan mekanis tanah tersebut harus diperbaiki. Perbaikan yang dilakukan dalam penelitian ini adalah mencampur bahan stabilisasi semen 2% dan pasir 10% dengan variasi kadar air sebanyak 53% (Liquid Limit), 33% (Indeks Plastis), 30% (Optimum) dan 20% (Plastic Limit). Uji sifat fisis dan mekanis meliputi uji Kadar Air dan uji California Bearing Ratio (CBR) dengan pemeraman (unsoaked) selama 7, 14, 21, dan 28 hari. Hasil uji menunjukkan nilai CBR meningkat dimulai pada kondisi kadar air 53% (LL) sebesar 0% di 7 hari hingga 0,4% pada 28 hari masa peram dengan kadar air 105,54%-63,11%, di kondisi kadar air 33% (IP) peningkatan nilai CBR sebesar 0%-3,62% dengan penurunan kadar air sebesar 88,31%-45,93%, pada kondisi kadar air 30% (OP) nilai CBR meningkat sebesar 0%-3,93% dengan kadar air 86,54%-40,23%, dan di kondisi kadar air 20% (PL) peningkatan nilai CBR sebesar 0,62% pada masa peram 7 hari hingga 6,60% di 28 hari dengan kadar air 72,80%-21,27%. Peningkatan dari nilai CBR tanah asli sebesar 0,62% hingga 6,60% setelah distabilisasi sebanyak 964,5%. Dari penelitian ini dapat disimpulkan bahwa stabilisasi yang dilakukan dengan semen dan pasir dengan penambahan kadar air, dapat memperbaiki sifat fisis dan mekanis tanah lempung lunak.

Kata kunci : CBR, Kadar Air, Pasir, Semen, Stabilisasi, Tanah Lempung Lunak

Soft clay soil is one type of base soil that often causes problems in various types of construction because its bearing capacity is low and its sensitivity to changes in water content is quite high. Therefore, the physical and mechanical properties of the soil must be improved. The improvements made in this study were mixing 2% cement and 10% sand stabilization materials with variations in water content of 53% (Liquid Limit), 33% (Plastic Index), 30% (Optimum) and 20% (Plastic Limit). Physical and mechanical property tests include Water Content tests and California Bearing Ratio (CBR) tests with curing (unsoaked) for 7, 14, 21, and 28 days. The test results showed that the CBR value increased starting from 53% water content (LL) by 0% in 7 days to 0.4% in 28 days of curing period with a water content of 105.54% -63.11%, in 33% water content (IP) the CBR value increased by 0% -3.62% with a decrease in water content of 88.31% -45.93%, in 30% water content (OP) the CBR value increased by 0% -3.93% with a water content of 86.54% -40.23%, and in 20% water content (PL) the CBR value increased by 0.62% in 7 days curing period to 6.60% in 28 days with a water content of 72.80% -21.27%. The increase in the original soil CBR value was 0.62% to 6.60% after being stabilized by 964.5%. From this study it can be concluded that stabilization carried out with cement and sand with the addition of water content can improve the physical and mechanical properties of soft clay soil. Keywords: CBR, Water Content, Sand, Cement, Stabilization, Soft Clay Soil