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"Skripsi ini membahas korelasi antara nilai CBR dan DCP untuk jenis tanah gambut Berengbengkel, Palangkaraya. Uji CBR merupakan uji yang sudah sangat dikenal secara umum khusunya pada pembuatan jalan raya dan timbunan tanah. Namun, uji CBR ini memiliki beberapa kekurangan. Untuk itu, digunakan DCP sebagai pengganti uji CBR. Penelitian yang pernah dilakukan, menghasilkan grafik korelasi nilai antara CBR dan DCP dengan perhitungan yang berbeda. Pada penelitian ini, akan dicari perhitungan korelasi nilai CBR dan DCP pada tanah gambut yang mendekati nilai CBR yang sebenarnya. Data didapatkan dengan pemadatan tanah, uji CBR laboratorium dan dilanjutkan dengan DCP yang keseluruhan kegiatannya berada di dalam laboratorium. Dari hasil analisa data, didapat perumusan nilai korelasi yang terjadi dalam fungsi logaritma. Dari perhitungan tersebut, diperoleh nilai CBR rata-rata dari tiap kadar air dengan nilai yang mendekati dengan kondisi sebenarnya.

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This paper discuss about the correlation between the CBR and DCP value for peat soil that come from Berengbengkel, Palangkaraya. The CBR test is well known in road construction and for embankment of soil. But, the CBR test has some disadvantages. On the other hand, we can use DCP test than CBR. Research that has been done in the past, has produce correlation graphic between CBR and DCP value with various calculations. In this research, we will find the correlation of CBR and DCP value in peat soil that close to the real CBR value. Output data is made from compaction of the soil, CBR laboratory test, and then continued with DCP test. From the analysis of the data, we can get calculation of the correlation in the logarithmic function. From this calculation, we can get the CBR value of every water content which the value is almost the same with the real condition."

"Uses of microorganisms in the civil engineering domain have been developed since several years ago. From several researches, microorganisms produced calcite was able to improve the mechanical properties of the soil and concrete. In the soil, they could increase the bearing capacity by producing calcite that would fulfill the pores of soil [Ivanov, 2008]. By reducing the pores, the soil will be more compact and it can increase its capacity. On the concrete material, it could be used to fix the cracking in the concrete or it could [Achal et.al. 2010] be used in mix design which able to improve the strength of concrete. The type of the bacteria which can produce calcite is from genera Bacillus. Growth of Bacillus subtilis studied in this paper was observed in laboratory of Microbiology at Universite Lille 1."

"Proses bio-sementasi atau yang biasa dikenal dengan MICP (Microbial Induced Calcite Precipitation) pada tanah sangat dipengaruhi oleh aktivitas enzim urease. Aktivitas urease yang tinggi, presipitasi urea dan kalsium klorida menjadi partikel kalsit juga akan meningkat. Enzim urease diperoleh dari B.subtilis dan Oceanobacillus sp. dengan nomor isolat P3BG41 dan P3BG43. Bakteri ditumbuhkan di bawah media B4 urine dan M63 dengan asam glutamat pada suhu 37oC dan pH +7 selama lima hari pengamatan. Isolat kemudian diukur harian kepadatan optik dan aktivitas urease. Bakteri dan kombinasi urea (CO(NH2)2) dan kalsium klorida (CaCl2) disuntikkan setiap hari ke dalam pasir untuk mendapatkan hasil optimum dari presipitasi kalsit. Nilai tertinggi aktivitas enzim urease terjadi pada hari kedua inkubasi. Sementara kepadatan optik berkurang pada hari kedua, kohesi tanah mencapai nilai tertinggi pada hari itu. Namun, nilai sudut gesekan pada hari kedua memiliki titik terendah dibandingkan dengan hari lainnya.

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Bio-cementation process or commonly known as MICP (Microbial Induced Calcite Precipitation) on soil is strongly influenced by urease enzyme activity. High of urease activity the precipitation of urea and calcium chloride into calcite particles will also increase. The urease enzyme is obtained from B.subtilis and Oceanobacillus sp. with isolat number P3BG41 and P3BG43. The bacteria were grown under B4 urine medium and medium M63 with glutamic acid at 37oC and pH +7 for five days observation. The isolats were then daily measured its optical density and urease activity. The bacteria and combination of urea (CO(NH2)2) and calcium chloride (CaCl2) were daily injected into the sand to obtain the optimum results from the calcite precipitation. The highest value of urease enzyme activity occurs on the second day incubation. While the optical density was reduced on the second day, the soil cohesion reaches the highest value at that day. However, the friction angle value on the second day has the lowest point compared to the other day."