Electronic Theses and Dissertation

ABSTRAK

Defleksi dan keretakan beton selalu dipengaruhi oleh kapasitas lentur. Beton mutu tinggi cenderung memiliki panas hidrasi tinggi, sehingga rentan terjadi retakan mikro, oleh karena itu diperlukan perawatan sejak dini. Teknik self-healing concrete menjadi metode yang dapat digunakan untuk menyembuhkan retakan beton. Metode penyembuhan ini melibatkan bakteri pada campuran beton yang aktif ketika terjadi keretakan dengan menghasilkan kalsit (CaCO3) yang berfungsi untuk menutup keretakan. Sifat beton yang lemah terhadap gaya tarik memungkinkan terjadinya retakan mikro dan dapat merambat menjadi retakan makro apabila retakan tersebut tidak terdeteksi. Sehingga muncul inovasi yang disebut dengan self-healing concrete (SHC), yaitu beton dapat menutupi retakan mikro secara mandiri tanpa adanya perlakuan dari manusia. Pada penelitian ini digunakan bakteri genus Bacilus sp, genus Staphylococcus sp, dan genus Solibacilus sp. Bakteri ini memiliki sifat endosfora yang tahan terhadap kondisi ekstrim seperti panas, kekeringan, dan zat kimia meskipun dalam keadaan tidak aktif. Benda uji yang digunakan yaitu balok dengan panjang 400 mm, lebar 100 mm, dan tinggi 100 mm, yang diberi satu buah besi ulir diameter 10 mm. Variasi campuran bakteri yang digunakan 0%; 0,5%; 0,6% dan 0,7% dari berat semen dan kapsul bakteri 10% dari berat agregat halus. Total benda uji sebanyak 50 buah, pengujian tahap awal setelah beton berumur 7 hari diberikan beban sebesar 70% mutu rencana (50 MPa) untuk memberikan retakan pada beton, kemudian dilakukan perawatan selama 21 hari setelah pemberian retak awal untuk melihat proses self-healing secara visual pertumbuhan Kalsit. Hasil kapasitas lentur rata-rata tertinggi didapatkan pada variasi beton dengan bakteri genus Bacillus sp 0,6% sebesar 6,34 ton dengan panjang kalsit rata-rata 41,00 mm. Dalam menganalisa karakterisasi struktur atom dari beton bakteri dilakukan pengujian XRD. Hasil pengujian menunjukkan beton bakteri genus Bacillus sp dengan persentase fase amorf paling tinggi yaitu 82,63% dan mengandung senyawa kalsit sebanyak 33,66%.

Kata kunci : Beton mutu tinggi, self-healing concrete, genus Bacillus sp, genus
Staphylococcus sp, genus Solibacillus sp, Kalsit, XRD.

ABSTRACT Concrete deflection and cracking are always influenced by flexural capacity. High quality concrete tends to have a high heat of hydration, making it susceptible to micro cracks, therefore early maintenance is required. The self-healing concrete technique is a method that can be used to heal concrete cracks. This healing method involves bacteria in the concrete mixture which are active when cracks occur by producing calcite (CaCO3) which functions to close the cracks. The weak nature of concrete against tensile forces allows micro cracks to occur and can propagate into macro cracks if the cracks are not detected. So an innovation emerged called self-healing concrete (SHC), namely concrete that can cover micro-cracks independently without any human intervention. In this study, bacteria of the genus Bacilus sp, genus Staphylococcus sp, and genus Solibacilus sp were used. This bacteria has endosphoric properties that can be adapted to concrete. The test object used is a beam 400 mm long, 100 mm wide and 100 mm high, which is provided with 10 mm deformed bar. Variations in the bacterial mixture used were 0%; 0.5%; 0.6% and 0.7% of the weight of cement and diatomaceous earth 10% of the weight of fine aggregate. A total of 50 test objects, the initial testing stage after the concrete was 7 days old was given a load of 70% of the design quality (50MPa) to give cracks to the concrete, then treatment was carried out for 21 days after giving the initial crack to visually see the self-healing process of calcite growth (CaCO3). The highest average flexural capacity results were obtained in the variation of concrete with 0.6% Bacillus sp genus bacteria of 6.34 tons with an average calcite length of 41.00 mm. In analyzing the atomic structure characteristics of bacterial concrete, XRD testing was carried out. The test results showed that the bacterial concrete of the genus Bacillus sp had the highest percentage of amorphous phase, namely 82.63% and contained 33.66% calcite compounds. Keywords : High-strength concrete, self-healing concrete, genus Bacillus sp, genus Staphylococcus sp, genus Solibacillus sp, Calcite, XRD.