ANALISIS PENAMBAHAN SERBUK BATU GAMPING TERHADAP NILAI POTENSIAL SWELLING PADA TANAH LEMPUNG EKSPANSIF DI DAERAH DRIYOREJO GRESIK

Tanah ekspansif atau tanah kembang susut adalah tanah yang mempunyai potensi swelling yang tinggi, sehingga sering menimbulkan masalah pada struktur bangunan di atasnya. Hasil tes awal pada tanah lempung yang diambil dari Driyorejo Gresik didapatkan nilai Index Plasticity (IP) kategori potential swelling yang sangat tinggi. Cara yang dipakai untuk proses stabilisasi tanah tersebut dengan stabilisasi kimia menggunakan serbuk batu gamping. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan serbuk batu gamping terhadap nilai potential swelling pada tanah lempung ekspansif di daerah Driyorejo Gresik. Penelitian ini merupakan penelitian eksperimen yang dilakukan di Laboratorium Mekanika Tanah UNESA dengan cara membuat campuran tanah lempung dan serbuk batu gamping dengan variasi campuran 0%, 5%, 10%, 15%, dan 20% dari berat tanah. Tes tanah dalam penelitian ini meliputi atterberg limit test (untuk mencari parameter IP), standart proctor test (untuk mencari parameter γd max dan Wc.opt) dan swelling test. Benda uji yang digunakan untuk swelling test dalam kondisi kepadatan tanah maksimum (γd max) dan kadar air optimum (Wc.opt) adalah tanah dari hasil standart proctor test. Jumlah benda uji untuk swelling test ada 5 buah dari masing-masing variasi campuran serbuk batu gamping. Hasil penelitian Potential Swelling pada tanah lempung dengan campuran 0%, 5%, 10%, dan 15% serbuk batu gamping masing-masing sebesar 24,85%, 20,68%, 14,70% dan 8,71% termasuk tanah dengan potential swelling tinggi, sedangkan untuk campuran 20% serbuk batu gamping mendapat nilai 4,85% termasuk tanah dengan potential swelling kategori sedang. Peneliti menyarankan untuk pekerjaan pemadatan tanah atau stabilisasi tanah menggunakan serbuk batu gamping agar menggunakan variasi campuran 20%, karena dengan komposisi campuran tersebut tanah lempung kembang-susut di Driyorejo Gresik sudah stabil dan dalam kategori swelling sedang. Kata Kunci : Tanah Ekspansif, Potential Swelling, Serbuk Batu Gamping, Stabilisasi, Tanah, Index PlasticitAbstract Abstract Expansive soil or expanded-shrinkage soil is the soil that has a high swelling potential, as consequence, it causes problem inside the structure of the building that existing on it. The result of preliminary tests on clay taken from Driyorejo Gresik has shown the Index Plasticity (IP) value determining the category of potential swelling that is very high. The way that is used for the process of soil stabilization above by chemical stabilization is limestone powder. This research was aimed to determine the effect of the addition of limestone powder to the value of potential swelling in expansive clays in the area of Driyorejo Gresik. This research is categorized as the experiment research that is carried out in Soil Mechanics Laboratory of State University of Surabaya by creating a mixture of clay and limestone powder with the mixed variation of 0%, 5%, 10%, 15%, and 20% of the weight of the soil. The test of soil in this study covered Atterberg limits tests (finding the IP parameter), standard proctor test (to find parameters of (γd max) and (Wc.opt) and swelling test. The specimens for swelling test used in the conditions of maximum density of the soil (γd max) and optimum water rate (Wc.opt) is the soil from the result of the standard proctor test. The number of specimens for swelling test is 5 pieces of each mixture variation of limestone powder. The result of the research dealing with Potential Swelling of clay with 0%, 5%, 10%, and 15% of mixed limestone powder each of 24,85%, 20,68%, 14,70% and 8,71% included the soil with high potential swelling , meanwhile for mixture 20% of limestone powder getting point on 4,85% included soil with potential swelling that is defined as medium categorized. Researcher suggests in term of soil compaction project or soil stabilization using limestone powder recommended to employ mixture variation 20%, since by using those mixed composition, the expanded-shrinked clay in Driyorejo Gresik has been stable and categorized into medium swelling. Keywords: Expansive Soil, Swelling Potential, Limestone Powder, Stabilization Soil, Index Plasticit