ANALISIS PENINGKATAN NILAI KUAT GESER DAN KUAT TEKAN TANAH LEMPUNG DENGAN PENAMBAHAN ABU SERBUK KAYU ANALYSIS OF INCREASING SHEAR STRENGTH AND COMPRESSIVE STRENGTH VALUES OF CLAY SOIL WITH THE ADDITION OF WOOD POWDER ASH

Rifqi, Muhammad and Nuraini, Rika (2023) ANALISIS PENINGKATAN NILAI KUAT GESER DAN KUAT TEKAN TANAH LEMPUNG DENGAN PENAMBAHAN ABU SERBUK KAYU ANALYSIS OF INCREASING SHEAR STRENGTH AND COMPRESSIVE STRENGTH VALUES OF CLAY SOIL WITH THE ADDITION OF WOOD POWDER ASH. Tugas Akhir thesis, University Of Technology Yogyakarta.

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Abstract

Tanah merupakan dasar dari suatu struktur bangunan. Setiap daerah memiliki karakteristik dan sifat tanah yang berbeda-beda. Contoh beberapa sifat tanah yang perlu diperhatikan adalah plastisitas tinggi, kuat geser, pemampasan besar atau perubahan volume dan penyusutan. Pengambilan sampel tanah dalam pengujian ini diambil di daerah dusun Ngrancah, Pendoworejo, Girimulyo Kulon Progo, D.I. Yogyakarta. Pengambilan sampel tanah yaitu jenis tanah tidak terganggu (undisturb), dan terganggu (disturb). Pengambilan dilakukan dengan mencangkul hingga kedalaman ± 20 - 30 cm dari permukaan tanah, dan menggunakan tabung hingga kedalaman ± 1 – 1,2 m. Penelitian dilakukan pada kondisi tanah asli serta kondisi tanah dicampur dengan bahan tambah berupa abu serbuk kayu. Variasi penambahan abu serbuk kayu 9%, 18%,dan 23% terhadap berat kering tanah. Dari hasil pengujian analisis ukuran butir tanah sistem klasifikasi AASHTO, tanah yang berlokasi di daerah dusun Ngrancah, Pendoworejo, Girimulyo, Kulon Progo, Yogyakarta termasuk kedalam kelompok A-6 yaitu tanah berlempung dengan penilaian umum sebagai tanah dasar sedang sampai buruk. Sedangkan pada sistem klasifikasi tanah USCS, di daerah dusun Ngrancah, Pendoworejo, Girimulyo, Kulon Progo, Yogyakarta digolongkan sebagai tanah berbutir halus dan termasuk kedalam kelompok CL (Clay Low-Plasticity) yaitu tanah lempung tak organik dengan plastisitas rendah sampai sedang, lempung berkerikil, lempung berpasir, lempung lanau, lempung kurus. Dari hasil pengujian kuat geser diperoleh bahwa penambahan abu serbuk kayu mengalami peningkatan maksimum terhadap nilai kohesi (c) dan sudut geser (ϕ) yang semakin membaik dari nilai kohesi tanah asli yaitu kohesi pada persentase 23% sebesar 51 kN/m^2, dan sudut geser meningkat pada persentase 9% sebesar 37°, nilai kuat geser optimum pada persentase 23% sebesar 66,63kg/cm2, hal tersebut karena abu serbuk kayu mengandung SiO2 yang dapat mempengaruhi ikatan antar butiran. Dari hasil pengujian kuat tekan bebas qu tanah asli mengalami peningkatan setelah penambahan abu serbuk kayu 9%, yaitu 1,00, 18% yaitu 1,73, kemudian nilai qu mengalami penurunan saat penambahan abu serbuk kayu bakar 23% yaitu 1,54. Hal tersebut bahwa tingkat daya dukung tanah menjadi lebih baik dengan penambahan abu serbuk kayu 18% karena mengalami peningkatan pada nilai qu. Hal ini dapat memberikan pengaruh terhadap peningkatan nilai kuat tekan dan daya dukung pada tanah lempung. Kata kunci: Tanah Lempung, Abu Serbuk Kayu, Kuat Geser Langsung, Kuat Tekan Bebas Soil is the basis of a building structure. Each region has different characteristics and soil properties. Examples of several soil properties that need to be considered are high plasticity, shear strength, large compression or changes in volume and shrinkage. Soil samples taken in this test were taken in the hamlet area of Ngrancah, Pendoworejo, Girimulyo Kulon Progo, D.I. Yogyakarta. Soil samples are undisturbed and disturbed soil types. Collection is carried out by hoeing to a depth of ± 20 - 30 cm from the ground surface, and using a tube to a depth of ± 1 - 1.2 m. The research was carried out in original soil conditions as well as soil conditions mixed with additional materials in the form of sawdust ash. Variations in the addition of sawdust ash of 9%, 18%, and 23% to the dry weight of the soil. From the results of testing on soil grain size analysis of the AASHTO classification system, the soil located in the hamlet area of Ngrancah, Pendoworejo, Girimulyo, Kulon Progo, Yogyakarta is included in group A-6, namely clayey soil with a general assessment as moderate to poor subgrade. Meanwhile, in the USCS soil classification system, it is classified as fine-grained soil and is included in the CL (Clay Low-Plasticity) group, namely inorganic clay soil with low to medium plasticity, gravelly clay, sandy clay, silt clay, and lean clay. From the results of the shear strength test, it was found that the addition of sawdust ash experienced a maximum increase in the cohesion value (c) and friction angle (ϕ) which increasingly improved from the original soil cohesion value, namely cohesion at a percentage of 23% at 51 kN/m^2, and the angle shear increases at a percentage of 9% by 37°, the optimum shear strength value at a percentage of 23% is 66.63kg/cm2, this is because sawdust ash contains SiO2 which can affect the bond between granules. From the test results, the unconfined compressive strength qu of the original soil increased after adding 9% sawdust ash, namely 1.00, 18%, namely 1.73, then the qu value decreased when adding 23% sawdust ash, namely 1.54. It shows that the level of soil carrying capacity becomes better with the addition of 18% sawdust ash because it increases the qu value. This can have an influence on increasing the compressive strength and bearing capacity values of clay soil. Keywords: Clay Soil, Sawdust Ash, Direct Shear Strength, Unconfined Compressive Strength

Item Type:	Thesis (Skripsi, Tugas Akhir or Kerja Praktek) (Tugas Akhir)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Divisions:	Fakultas Sains dan Teknologi > S1 Teknik Sipil
Depositing User:	Kaprodi S1 Teknik Sipil UTY
Date Deposited:	19 Jun 2026 06:07
Last Modified:	19 Jun 2026 06:07
URI:	http://eprints.uty.ac.id/id/eprint/20127

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