[ABSTRAK
Pada umumnya kerusakan pada strukstur ataupun kontruksi jalan biasanyadisebabkan oleh tanah dasar yang mempunyai kemampuan kembang susut yangcukup tinggi atau yang sering disebut tanah ekspansif. Tanah ekspansifmempunyai sifat yang berbeda dari tanah pada umumnya seperti nilai plastisitasyang cukup tinggi, potensi kembang susut dan kemampatan atau perubahanvolume yang cukup besar, selain itu tanah ini mempunyai kekuatan geser yangrendah. Untuk mengurangi kerusakan yang disebabkan oleh tanah ekspansif,maka diperlukan suatu studi penelitian untuk stabilitasi tanah baik yang sudahdilakukan sebelumnya maupun yang telah dilakukan saat ini. Stabilitasi tanahekspansif yang murah dan efektif adalah dengan menambahkan bahan kimiatertentu, dengan penambahan bahan kimia dapat mengikat mineral lempungmenjadi padat, sehingga mengurangi kembang susut tanah lempung ekspansif.Oleh karena itu dalam penelitian ini menggunakan beberapa zat stabilisasi antaralain pasir, semen dan kapur yang mudah didapat dan cukup efektif untukstabilisasi tanah ekspansif. Dengan penambahan zat tersebut diharapkan mampumemperbaiki sifat-sifat tanah ekspansif yang kurang baik.Pengujian pada tanah ekspansif yang diambil di daerah cikarang, jawa barat inimeliputi pengujian sifat fisis dan mekanik. Untuk tanah asli dilakukan ujilaboratorium meliputi Spesivic gravity, Atterberg Limit, Grain size, Compactionstandard, Unconfined compression test (UCT) dan Triaksial ConsolidatedUdrained (CU). Untuk pengujian tanah campuran baik pasir dan kapur (10% pasir+ 5% kapur, 10% pasir + 10% kapur, 10% pasir +15% kapur) maupun pasir dansemen (10% pasir + 5% semen, 10% pasir + 10% semen, 10% pasir +15% semen)dilakukan pengujian SG, atterberg limit, Compaction standard, pengujian kuattekan bebas (UCT) dan Triaksial Consolidated Undrained (CU). Pengujian akhiryang dilakukan untuk mendapatkan kekuatan geser tanah adalah dengan ujiunconfined compression test (UCT) atau uji kuat tekan bebas dan TriaksialConolidated Undrained (CU) dengan terlebih dahulu melakukan pemeramanselama 0, 4 ,7, 14 hari. Hasil yang didapat untuk triaksial CU kemudian dianalisadengan metode Critical state concept.Hal ini dilakukan dengan tujuan untuk menganalisa sejauh mana pengaruh waktupemeraman terhadap kuat geser tanah tanah lempung ekspansif yang distabilisasidengan semen, kapur dan pasir. Membandingkan parameter-parameter kuat gesertanah tanpa bahan campuran dan dengan campuran. Mengetahui persentase variasicampuran pasir dan semen, pasir dan kapur untuk stabilisasi tanah ekspansif yangbaik dan efektif setelah pengujian laboratorium.ix Universitas IndonesiaHasil yang diperoleh adalah Tanah ini termasuk ke dalam tanah lempunganorganik dengan plastisitas tinggi, tanah ekspansif (CH). variasi campuran kapurdan pasir dapat menurunkan nilai indeks plastisitas tanah, begitu pula dengancampuran pasir dan semen. Namun penggunaan campuran pasir dan sementerbukti lebih efektif (dengan perentase yang sama) dalam menurunkan indeksplastisitas tanah dibandingkan dengan pasir dan kapur. Adanya perubahankonsistensi dari tanah asli setelah dicampur dengan bahan stabilisasi ditambahdengan waktu pemeraman yang menunjukkan adanya perbaikan tanah.Percobaan unconfined baik campuran pasir dan semen maupun pasir dan kapursetelah pemeraman menunjukkan kenaikan nilai qu, semakin lama waktupemeraman semakin besar nilai kenaikan nilai qu nya yang ditandai dengan masapemeraman 14 hari adalah yang terbaik. Untuk pengujian UCT maupun triaksialCU, masa pemeraman 0 hari kurang menunjukkan hasil yang berarti. Dari hasilUCT Pencampuran 5% Semen+10% Pasir dengan pemeraman jauh lebih baikdibandingkan dengan campuran 15% Kapur + 10% Pasir dengan waktupemeraman yang sama. Sedangkan campuran 15% semen + 10% pasirmemberikan hasil yang sangat signifikan dalam nilai qu nya jika dibandingkandengan campuran tanah 15% Kapur + 10% pasir namun dari segi biaya cukupmahal, disisi lain campuran 15% kapur + 10% pasir juga dapat memperbaiki tanahdalam hal stabilisasi yang lebih ekonomis. Pengaruh pencampuran 15% Kapur +10% pasir untuk pengujian triaksial CU terbukti dapat meningkatkan nilaiparameter kuat geser tanah,terutama nilai sudut geser tanah asli mengalamipeningkatan sebesar 11.41o dari 12.940 menjadi 24.350 setelah waktu pemeraman14 hari namun nilai kohesi tidak banyak berubah dari tanah asli, hal inidisebabkan pasir yang bersifat lepas menurunkan kohesi tanah namun menaikkannilai sudut geser.;
ABSTRACT
In general, the damage of structures or road consructions are caused bysub grade that has capability to shrunk and expand highly, or often called as theexpansive soil. Expansive soil has different properties from other type of soil ingeneral, such as the high plasticity index, the shrinkage potential and thecongestion or significant change in volume; however, it has a low shear strength.To reduce damage caused by expansive soil, there is an urgent need to conductmore research regarding its stability. The relatively cheap and effective way tostabilize expansive soil is by adding chemical agents that will bind clay minerals,thereby reducing shrinkage. Therefore this study uses several stabilizingsubstances such as sand, cement and lime that are easily available and quiteeffective to stabilize this type of soil. The addition of these substances is expectedto improve the properties of expansive soil.Experiment of expansive soil samples from Cikarang, West Java, consisted of aseries physical and mechanical properties tests. The original soil was examinedwith laboratory tests: Spesific gravity, Atterberg Limits, Grain size, Compactionstandard, unconfined compression test (UCT) and Triaksial ConsolidatedUndrained (CU). And the mixture of sand and limestone (10% sand + 5% lime,10% sand + 10% lime, 10% sand +15% lime); and sand and cement (10% sand +5% cement, 10% sand + 10% cement, 10% sand cement +15%) were examinedwith similar tests as the original soil except the grain size. The final test to obtainsoil shear strength was the Unconfined Compression Test (UCT) and TriaxialConsolidated Undrained (CU). Prior to the tests, curing was performed for 0, 4, 7,and 14 days. The results from the triaxial CU were then analyzed by the criticalstate concept method.The objectives of this study are to analyze the extent of influence of curing timeon shear strength of expansive clay soil stabilized with cement, lime and sand; tocompare the soil shear strength parameters with and without mixture; and toinvestigate the optimum percentage of mixture variation (sand-cement and sandlime)from laboratory experiment.From the experiment, the soil is categorized as anorganic clay with high plasticityindex, expansive soil (CH). The Mixture of variation sand ? lime and sand -cement can reduce soil plasticity index. However the variaton sand ? cement (insame persentation) mixture more effective to reduce soil plasticity indeks thanvariation sand ? lime mixture. Moreover, the alteration of original soil consistencyafter mixed with stabilizing agent and the increasing of curing time demonstrate asoil improvement.xi Universitas IndonesiaUnconfined test both for sand-cement and sand-lime mixture after curing showedan increased value of qu, the longer the curing time the greater the increase invalue, in which 14 days curing time gains the greatest result. From UCT andtriaxial CU tests, 0 days curing period showed less significant result. The mixtureof 5% cement + 10% sand with curing is better than the mixture of 15% lime+10% sand with same curing time. The mixture of 15% cement +10% sand givessignificant result in improving qu rather than the mixture of 15% lime + 10%sand though quite expensive. The mixture of 15% lime +10% sand can alsoimprove soil in more economical term. The effect of mixing 15% lime + 10%sand from CU triaxial test proved to increase the value of shear strengthparameters, especially soil shear angle values increased after 14 days curing timefor 11.41o from 12.940 to 24.350. However, the cohesion value decreased 6,13Kpa, in which quite similar from the original soil. This is due to the characteristicof loose sand that reduces soil cohesion while at the same time increases soil shearangle., In general, the damage of structures or road consructions are caused bysub grade that has capability to shrunk and expand highly, or often called as theexpansive soil. Expansive soil has different properties from other type of soil ingeneral, such as the high plasticity index, the shrinkage potential and thecongestion or significant change in volume; however, it has a low shear strength.To reduce damage caused by expansive soil, there is an urgent need to conductmore research regarding its stability. The relatively cheap and effective way tostabilize expansive soil is by adding chemical agents that will bind clay minerals,thereby reducing shrinkage. Therefore this study uses several stabilizingsubstances such as sand, cement and lime that are easily available and quiteeffective to stabilize this type of soil. The addition of these substances is expectedto improve the properties of expansive soil.Experiment of expansive soil samples from Cikarang, West Java, consisted of aseries physical and mechanical properties tests. The original soil was examinedwith laboratory tests: Spesific gravity, Atterberg Limits, Grain size, Compactionstandard, unconfined compression test (UCT) and Triaksial ConsolidatedUndrained (CU). And the mixture of sand and limestone (10% sand + 5% lime,10% sand + 10% lime, 10% sand +15% lime); and sand and cement (10% sand +5% cement, 10% sand + 10% cement, 10% sand cement +15%) were examinedwith similar tests as the original soil except the grain size. The final test to obtainsoil shear strength was the Unconfined Compression Test (UCT) and TriaxialConsolidated Undrained (CU). Prior to the tests, curing was performed for 0, 4, 7,and 14 days. The results from the triaxial CU were then analyzed by the criticalstate concept method.The objectives of this study are to analyze the extent of influence of curing timeon shear strength of expansive clay soil stabilized with cement, lime and sand; tocompare the soil shear strength parameters with and without mixture; and toinvestigate the optimum percentage of mixture variation (sand-cement and sandlime)from laboratory experiment.From the experiment, the soil is categorized as anorganic clay with high plasticityindex, expansive soil (CH). The Mixture of variation sand – lime and sand -cement can reduce soil plasticity index. However the variaton sand – cement (insame persentation) mixture more effective to reduce soil plasticity indeks thanvariation sand – lime mixture. Moreover, the alteration of original soil consistencyafter mixed with stabilizing agent and the increasing of curing time demonstrate asoil improvement.xi Universitas IndonesiaUnconfined test both for sand-cement and sand-lime mixture after curing showedan increased value of qu, the longer the curing time the greater the increase invalue, in which 14 days curing time gains the greatest result. From UCT andtriaxial CU tests, 0 days curing period showed less significant result. The mixtureof 5% cement + 10% sand with curing is better than the mixture of 15% lime+10% sand with same curing time. The mixture of 15% cement +10% sand givessignificant result in improving qu rather than the mixture of 15% lime + 10%sand though quite expensive. The mixture of 15% lime +10% sand can alsoimprove soil in more economical term. The effect of mixing 15% lime + 10%sand from CU triaxial test proved to increase the value of shear strengthparameters, especially soil shear angle values increased after 14 days curing timefor 11.41o from 12.940 to 24.350. However, the cohesion value decreased 6,13Kpa, in which quite similar from the original soil. This is due to the characteristicof loose sand that reduces soil cohesion while at the same time increases soil shearangle.] |
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