PENGARUH PENAMBAHAN BOTTOM ASH TERHADAP NILAI PEMADATAN DAN CALIFORNIA BEARING RATIO (CBR) PADA TANAH LEMPUNG DI RUAS JALAN KEDAMEAN DAWARBELANDONG

EFFECT OF BOTTOM ASH ADDITION ON COMPACTION VALUE AND CALIFORNIA BEARING RATIO (CBR) ON CLAY SOIL IN KEDAMEAN DAWARBELANDONG ROAD SECTION

Jalan merupakan salah satu sarana prasarana yang sangat dibutuhkan dalam kehidupan untuk menunjang seluruh kegiatan manusia. Namun sering dijumpai kondisi tanah dasaar (subgrade) yang memiliki daya dukung yang kurang memadai untuk menerima beban kendaraan yang melewatinya sehingga perlu adanya perbaikan karakteristik tanah agar lebih baik dari sebelumnya. Perbaikan tanah dengan penambahan bahan campuran sering digunakan, salah satunya dengan menggunakan abu bawah limbah pembakaran batu bara (bottom ash) karena bottom ash dapat membantu perbaikan tanah.

Penelitian ini bertujuan untuk mengetahui bagaimana pengaruh penambahan bottom ash pada tanah lempung terhadap nilai California bearing ratio (CBR). Penelitian ini merupakan penelitian eksperimental di laboratorium dengan membuat benda uji berupa campuran tanah lempung dengan bottom ash pada presentase 22%, 27%, 32% dan 37%. Beberapa pengujian yang dilakukan diantaranya uji Atterberg limit (batas cair dan batas plastis) untuk mengetahui nilai indeks plastisitas, uji berat jenis, uji pemadatan (standart proctor test) serta uji California bearing ratio (CBR).

Hasil penelitian menunjukkan bahwa bottom ash dapat meningkatkan nilai California bearing ratio (CBR) tanah hingga pada presentase tertentu, apabila penambahan bottom ash melebihi presentase tersebut, maka akan menyebabkan nilai bottom ash mengalami penurunan kembali seiring bertambahnya presentase bottom ash yang digunakan. Nilai CBR pada tanah asli penetrasi 0,1” (10%), sedangkan penetrasi 0,2” (9,83%), nilai CBR pada tanah lempung + bottom ash 22% penetrasi 0,1” (13,36%), penetrasi 0,2” (13,02%), nilai CBR pada tanah lempung + bottom ash 27% penetrasi 0,1” (13,00%), penetrasi 0,2” (12,48%), nilai CBR pada tanah lempung + bottom ash 32% penetrasi 0,1” (12,25%), penetrasi 0,2” (11,94%), nilai CBR pada tanah lempung + bottom ash 37% penetrasi 0,1” (7,36%), penetrasi 0,2” (6,72%).

Kata Kunci: tanah lempung ekspansif, bottom ash, nilai CBR

Roads are one of the infrastructure facilities needed in life to support all human activities. However, it is often found that the condition of the subgrade does not have sufficient bearing capacity to support the load of vehicles passing over it, so it is necessary to improve the soil characteristics to make it better than before. Soil improvement with the addition of mixed materials is often used, one of which is the use of coal combustion waste bottom ash (bottom ash) because bottom ash can help improve soil.

This research aims to determine the effect of adding bottom ash to clay soil on the California Bearing Ratio (CBR) value. This study is an experimental laboratory investigation that involves creating test specimens by mixing clay soil with bottom ash at percentages of 22%, 27%, 32%, and 37%. Several tests were conducted, including Atterberg limit tests (liquid limit and plastic limit) to determine the plasticity index, specific gravity tests, compaction tests (standard Proctor test), and California Bearing Ratio (CBR) tests.

The research findings indicate that bottom ash can enhance the California Bearing Ratio (CBR) of soil up to a certain percentage. If the addition of bottom ash exceeds this percentage, the CBR value will decline as the percentage of bottom ash used increases. The CBR value for original soil at a penetration of 0.1" is 10%, while at a penetration of 0.2", it is 9.83%. For clay soil mixed with 22% bottom ash, the CBR values are 13.36% at 0.1" and 13.02% at 0.2". For clay soil mixed with 27% bottom ash, the values are 13.00% at 0.1" and 12.48% at 0.2". When mixed with 32% bottom ash, the values drop to 12.25% at 0.1" and 11.94% at 0.2". Finally, for clay soil mixed with 37% bottom ash, the CBR values are significantly lower at 7.36% for a penetration of 0.1" and 6.72% for a penetration of 0.2".

Keywords: expansive clay soil, bottom ash, CBR value