Electronic Theses and Dissertation

Beton mutu ultra tinggi merupakan material konstruksi generasi terbaru yang dirancang dengan mutu rencana kuat tekan dan kepadatan matriks yang tinggi, serta porositas rendah. Salah satu kerusakan yang umum dialami pada beton adalah keretakan. Kuat tarik belah beton merupakan suatu parameter penting dalam menahan retak akibat perubahan kadar air, suhu dan pembebanan. Self-healing concrete merupakan kemampuan beton dalam memperbaiki keretakan pada beton itu sendiri melalui mekanisme Microbially Induced Calcite Precipitation (MICP) yang memanfaatkan bakteri ureolitik penghasil enzim urease guna menghidrolisis urea dan menghasilkan endapan kalsit (CaCO₃) untuk menutup retakan secara alami. Penelitian ini bertujuan mengkaji pengaruh bakteri Solibacillus sp. sebagai media self-healing concrete terhadap kuat tarik belah beton mutu ultra tinggi. Bakteri dienkapsulasi menggunakan tanah diatomae dengan variasi 0,5%, 0,6%, dan 0,7% terhadap berat semen, pada faktor air aemen sebesar 0,19. Benda uji yang digunakan berbentuk silinder berukuran 150 mm × 300 mm sebanyak 18 buah, yang terdiri dari 12 benda uji dengan bakteri dan 6 benda uji kontrol tanpa bakteri. Retak awal diberikan melalui pembebanan tekan maksimal 70% dari kapasitas benda uji kontrol pada umur 7 hari. Perawatan dilakukan dengan cara perendaman benda uji selama 28 hari pasca pemberian retak. Pengujian kuat tarik belah dilaksanakan pada umur 28 hari pasca pemberian retak mengacu pada standar ASTM (American Society for Testing and Materials). Hasil penelitian menunjukkan nilai kuat tarik belah rata-rata pada variasi bakteri 0,5%, 0,6%, dan 0,7% berturut-turut adalah 5,60 MPa, 5,00 MPa, dan 4,63 MPa. Beton dengan penambahan bakteri Solibacillus sp. memiliki kekuatan sebesar 67,70% dibandingkan beton tanpa penambahan bakteri.

Ultra-High Performance Concrete (UHPC) is a newest-generation construction material designed with a high design compressive strength and matrix density, along with low porosity. One of the most common forms of damage experienced by concrete is cracking. Splitting tensile strength is an important parameter in resisting cracking caused by changes in moisture content, temperature, and loading. Self-healing concrete is the ability of concrete to repair its own cracks through the mechanism of Microbially Induced Calcite Precipitation (MICP), which utilizes ureolytic bacteria producing the urease enzyme to hydrolyze urea and generate calcite (CaCO₃) precipitates that seal cracks naturally. This study aims to examine the effect of Solibacillus sp. bacteria as a self-healing medium on the splitting tensile strength of Ultra-High Performance Concrete. The bacteria were encapsulated using diatomaceous earth at variations of 0.5%, 0.6%, and 0.7% by weight of cement, with a water cement ratio of 0.19. The specimens used were cylindrical, measuring 150 mm × 300 mm, totaling 18 specimens, consisting of 12 specimens containing bacteria and 6 control specimens without bacteria. Initial cracks were induced through compressive loading at a maximum of 70% of the control specimen's capacity at 7 days of age. Curing was carried out by immersing the specimens for 28 days after crack induction. Splitting tensile strength testing was conducted at 28 days after crack induction, in accordance with ASTM (American Society for Testing and Materials) standards. The results showed that the average splitting tensile strength values for bacterial variations of 0.5%, 0.6%, and 0.7% were 5.60 MPa, 5.00 MPa, and 4.63 MPa, respectively. Concrete with the addition of Solibacillus sp. bacteria achieved 67.70% of the strength of concrete without bacterial addition.