<![CDATA[Abstrak Tanah lempung lunak sering menjadi kendala dalam pekerjaan konstruksi karena daya dukungnya rendah dan sifatnya mudah berubah akibat kadar air. Untuk mengatasi hal tersebut, penelitian ini dilakukan dengan menstabilisasi tanah menggunakan campuran serbuk batu kapur 10% dan limbah beton sebanyak 5%, 10%, dan 15% sebagai bahan alternatif ramah lingkungan. Serangkaian pengujian laboratorium seperti berat jenis, analisa ukuran butir, atterberg limit, pemadatan, california bearing ratio (CBR), dan swelling dilakukan setelah masa pemeraman selama 14 hari. Hasil menunjukkan bahwa campuran terbaik terdapat pada variasi 10% serbuk batu kapur dan 15% limbah beton. Pada variasi ini, indeks plastisitas menurun 85,90%, dari 36,60% menjadi 5,15%. Nilai CBR unsoaked meningkat 435,38%, dari 6,2% menjadi 33,2%, sedangkan nilai CBR soaked meningkat 523,66%, dari 4,65% menjadi 29%. Nilai swelling pun mengalami penurunan sebesar 89,18%, dari 6,47% menjadi 0,70%. Hasil ini membuktikan bahwa kombinasi bahan tersebut efektif memperbaiki karakteristik tanah lempung lunak. Kata kunci: Stabilisasi, Lempung, Limbah Beton, Serbuk Batu Kapur, California Bearing Ratio Abstract Soft clay soils often pose challenges in construction due to their low bearing capacity and high sensitivity to moisture content. To address this issue, this study stabilized soft clay using a mixture of 10% limestone powder and concrete waste at 5%, 10%, and 15% as environmentally friendly alternative materials. Laboratory tests—including specific gravity, grain size analysis, Atterberg limits, compaction, California Bearing Ratio (CBR), and swelling—were conducted after 14 days of curing. The results showed the optimal mix was 10% limestone powder and 15% concrete waste. In this variation, the plasticity index decreased by 85.90%, from 36.60% to 5.15%. The unsoaked CBR value increased by 435.38%, from 6.2% to 33.2%, while the soaked CBR value rose by 523.66%, from 4.65% to 29%. Swelling also decreased significantly by 89.18%, from 6.47% to 0.70%. These findings confirm that the material combination effectively improves the engineering properties of soft clay soils. Keywords: Stabilization, Clay, Concrete Waste, Limestone Powder, California Bearing Ratio]]>
