PENGARUH PENAMBAHAN SEMEN PORTLAND JENIS II TERHADAP KUAT TEKAN BEBAS TANAH LEMPUNG

ABSTRAK

Negara Republik Indonesia adalah negara yang mempunyai berbagai jenis-jenis tanah dengan karakteristik dan tipe masing-masing. Tanah lempung ekspansif memiliki plastisitas tinggi, dan berpotensi kembang susut besar, serta daya dukung yang sangat rendah sehingga kurang memenuhi syarat sebagai tanah dasar
konstruksi. Stabilisasi tanah adalah usaha untuk meningkatkan stabilitas dan kapasitas daya dukung tanah. Penelitian ini bertujuan untuk menganalisis pengaruh penambahan semen Portland jenis II terhadap sifat fisis dan sifat mekanis tanah lempung ekspansif yang berasal dari Exs Jalan Tol Semarang–Demak, Provinsi Jawa Tengah. Penelitian dilakukan melalui pengujian laboratorium di Universitas 17 Agustus 1945 Semarang terhadap tanah asli dan tanah yang distabilisasi dengan variasi penambahan semen Portland jenis II sebesar 100 kg/m3, 200 kg/m3, dan 300 kg/m3 dengan jumlah total sampel sebanyak 15 (lima belas) dan masa pemeraman 28 hari. Pengujian sifat fisis meliputi kadar air, berat jenis, berat volume basah, analisis butiran, dan batas konsistensi (Atterberg Limit), sedangkan sifat mekanis diuji menggunakan Unconfined Compressive Strength (UCS). Hasil pengujian tanah asli menunjukkan kadar air rata-rata 57,877%, nilai Liquid Limit (LL) 52,842%, Plastic Limit (PL) 32,156%, dan Plasticity Index (PI) 20,686% yang mengindikasikan tanah termasuk lempung berplastisitas tinggi (A-7-6 menurut AASHTO). Nilai kuat tekan bebas (qu) rata-rata tanah asli sebesar 0,062 kg/cm2. Setelah penambahan semen, nilai qu rata-rata meningkat menjadi 6,984 kg/cm2 (100 kg/m3), 7,222 kg/cm2 (200 kg/m3), dan 7,492 kg/cm2 (300 kg/m3), dengan nilai maksimum mencapai 7,856 kg/cm2 pada variasi 300 kg/m3. Hasil penelitian menunjukkan bahwa penambahan semen Portland tipe II secara signifikan meningkatkan daya dukung dan kestabilan tanah lempung lunak.

Kata kunci: stabilisasi tanah, lempung ekspansif, semen Portland tipe II, Atterberg Limit, kuat tekan bebas (UCS)

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ABSTRACT

The Republic of Indonesia is a country that has various types of soil with their own characteristics and types. Expansive clay soil has high plasticity, large shrinkage potential, and low bearing capacity so it does not meet the requirements as a
construction base soil. Soil stabilization is an effort to increase the stability and bearing capacity of the soil. This study aims to analyze the effect of adding Portland cement type II on the physical and mechanical properties of expansive clay soil originating from the Exs Semarang-Demak Toll Road, Central Java. The study was conducted through laboratory in University 17 Agustus 1945 Semarang testing of native soil and stabilized soil with variations in cement portland type II addition of
100 kg/m3, 200 kg/m3, and 300 kg/m3 with a total of 15(fifteen) samples and a curing period of 28 days. Physical property testing includes water content, specific gravity, wet volume weight, grain analysis, and consistency limit (Atterberg Limit), while mechanical properties were tested using Unconfined Compressive Strength (UCS). The results of the original soil test showed an average water content of 57.877%, a Liquid Limit (LL) value of 52.842%, a Plastic Limit (PL) of 32.156%, and a Plasticity Index (PI) of 20.686%, which indicated that the soil was classified as high-plasticity clay (A-7-6 according to AASHTO). The average unconfined compressive strength (qu) value of the original soil was 0.062 kg/cm2. After the addition of cement, the average qu value increased to 6.984 kg/cm2 (100 kg/m3), 7.222 kg/cm2 (200 kg/m3), and 7.492 kg/cm2 (300 kg/m3), with a maximum value reaching 7.856 kg/cm2 at a variation of 300 kg/m3. The results showed that the
addition of Portland cement type II significantly increased the bearing capacity and stability of soft clay soil.

Keywords: soil stabilization, expansive clay, Portland cement type II, Atterberg Limit, unconfined compressive strength (UCS)