Hubungan Modulus Young terhadap Kuat Tekan Beton Geopolimer Berbasis Fly Ash Tipe C dengan Variasi Molaritas NaOH Pencampuran Metode Kering

Bastian, Muhammad Yusril (2021) Hubungan Modulus Young terhadap Kuat Tekan Beton Geopolimer Berbasis Fly Ash Tipe C dengan Variasi Molaritas NaOH Pencampuran Metode Kering. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Perkembangan infrastruktur tidak lepas dari penggunaan beton sebagai struktur bangunan dengan material utamanya adalah semen portland. Beton punya kelemahan yakni terjadi retak (crack) akibat proses hidrasi yang mengeluarkan panas jika tidak dirawat pada suhu yang lembab. Oleh sebab itu dibutuhkan bahan pengganti semen portland dengan didasarkan kandungan unsur silika alumina yang reaktif. Material tersebut adalah fly ash tipe C dengan kadar SiO3 + Al2O3 + Fe2O3 minimal 50%. Kandungan silika dan alumina menyebabkan reaksi polimerisasi ketika sehingga disebut beton geopolimer. Beton bersifat elastis akibat beban yang menyebabkan deformasi sehingga timbul regangan. Sifat ini terjadi ketika 40% tegangan maksimum yang disebut modulus elastisitas atau modulus young. Umumnya modulus young beton dihitung secara empiris Ec = 4700√fc’. Persamaan ini belum tentu berlaku bagi beton geopolimer karena memiliki karakteristik yang berbeda dengan beton konvensional. Modulus young yang tinggi menunjukkan kemampuan beton menahan beban besar dengan kondisi regangan kecil. Perlu analisis modulus young beton geopolimer sebagai struktur bangunan.
Penelitian ini bertujuan memahami hubungan modulus young statis maupun dinamis terhadap kuat tekan beton geopolimer dengan metode pencampuran kering. Metode ini berbeda dengan metode basah dimana semen geopolimer yang terdiri fly ash tipe C, NaOH dan Na2SiO3 digiling bersama sebelum dicampur material lain terutama air sebagai reaktor pada reaksi polimerisasi. Dilakukan variasi molaritas NaOH mulai 12 M, 14 M, 16 M dan 18 M dengan rasio NaOH : Na2SiO3 sebesar 1 : 1 dalam satuan volume. Benda uji beton geopolimer yang dibuat yakni silinder berukuran 10 x 20 cm. Pengujian beton geopolimer meliputi uji slump, kecepatan gelombang (v), kuat tekan (fc), poisson ratio (µ), modulus young statis (Ec) dan modulus young dinamis (Ed) dimana semua uji memiliki keterkaitan. Uji v dan Ed merupakan Non-Destructive Test dengan metode UPV (Ultrasonic Pulse Velocity), sedangkan uji fc’, µ dan Ec merupakan Destructive Test dengan metode Data Logger-LVDT. Belum ada yang menggunakan metode ini untuk uji modulus young beton karena umumnya menggunakan metode dial bacaan manual. Output metode Data Logger-LVDT berupa bacaan nilai beban serta deformasi horizontal dan vertikal setiap interval waktu tertentu. Data mentah akan terintegrasi langsung untuk diterima PC atau Laptop.
Hasil uji slump menunjukkan semakin besar molaritas NaOH menyebabkan nilai slump makin kecil yakni dari 12 M (190 mm) ke 18 M (135 mm). Uji cepat rambat gelombang (v), semakin besar molaritas NaOH menyebabkan nilai v makin besar pula yakni dari 12 M (3.383 m/s) ke 18 M (4.238 m/s) yang tergolong beton kualitas “Baik”. Uji poisson ratio (µ) menunjukkan tren yang tidak sejalan dengan kenaikan molaritas NaOH karena pada 12 M (0,05) melonjak tajam ke 14 M (0,47) kemudian turun ke 16 M (0,04) dan melonjak kembali ke 18 M (0,20). Kuat tekan (fc’) dan modulus young statis (Ec) juga menunjukkan tren yang tidak sejalan dengan kenaikan molaritas NaOH, justru ditemukan nilai optimumnya pada NaOH 16 M yakni fc’ = 81,16 MPa dan Ec = 46.903 MPa. Hubungan keduanya menghasilkan persamaan regresi polinomial y = -11,627x2 + 1870,4x – 28405. Uji modulus young dinamis (Ed) nilai optimumnya pada 14 M (427.994 MPa). Hubungan fc’ dengan Ed menghasilkan persamaan polinomial y = 17,953x2 – 424,59x + 338760. Nilai Ec dibanding Ed variasi NaOH 12 M; 14 M; 16 M; dan 18 M berturut-turut sebesar 8,7%; 9,0%; 11,1% dan 10,8%. Beton geopolimer 16 M menjadi variasi terbaik karena fc’ dan Ec memiliki nilai terbesar dengan µ terkecil. Sedangkan Ed, v dan slump menempati urutan kedua diantara variasi NaOH lainnya.
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Infrastructure development cannot be separated from the use of concrete as a building structure with the main material being portland cement. Concrete has a weakness that cracks occur due to the hydration process which releases heat if not treated at a humid temperature. Therefore, a substitute for portland cement is needed based on the content of reactive silica alumina elements. The material is fly ash type C with a minimum content of 50% SiO3 + Al2O3 + Fe2O3. The content of silica and alumina causes a polymerization reaction when so called geopolymer concrete. Concrete is elastic due to loads that cause deformation so that strain arises. This property occurs when 40% of the maximum stress is called the modulus of elasticity or Young's modulus. Generally, the Young's modulus of concrete is calculated empirically Ec = 4700√fc'. This equation does not necessarily apply to geopolymer concrete because it has different characteristics from conventional concrete. High Young's modulus indicates the ability of concrete to withstand large loads with small strain conditions. It is necessary to analyze the young modulus of geopolymer concrete as a building structure. This study aims to understand the relationship between static and dynamic Young's modulus on the compressive strength of geopolymer concrete by dry mixing method. This method is different from the wet method where geopolymer cement consisting of type C fly ash, NaOH and Na2SiO3 is ground together before being mixed with other materials, especially water as a reactor for the polymerization reaction. NaOH molarity was varied from 12 M, 14 M, 16 M and 18 M with a ratio of NaOH: Na2SiO3 of 1:1 in unit volume. The geopolymer concrete test object made is a cylinder measuring 10 x 20 cm. Geopolymer concrete testing includes slump test, wave velocity (v), compressive strength (fc), poisson ratio (µ), static young's modulus (Ec) and dynamic young's modulus (Ed) where all tests are related. The v and Ed tests are Non-Destructive Tests using the UPV (Ultrasonic Pulse Velocity) method, while the fc', and Ec tests are Destructive Tests using the Data Logger-LVDT method. No one has used this method to test the Young's modulus of concrete because they generally use the manual reading dial method. The output of the Data Logger-LVDT method is in the form of reading the value of the load as well as the horizontal and vertical deformations at a certain time interval. Raw data will be integrated directly to be received by PC or Laptop. The results of the slump test show that the greater the molarity of NaOH causes the slump value to be smaller, namely from 12 M (190 mm) to 18 M (135 mm). The wave propagation speed test (v), the greater the molarity of NaOH, the greater the v value, namely from 12 M (3,383 m/s) to 18 M (4,238 m/s) which is classified as "Good" quality concrete. Poisson ratio test (µ) shows a trend that is not in line with the increase in NaOH molarity because at 12 M (0.05) it jumped sharply to 14 M (0.47) then dropped to 16 M (0.04) and jumped back to 18 M (0.20). The compressive strength (fc') and young static modulus (Ec) also showed a trend that was not in line with the increase in NaOH molarity, in fact found the optimum value for 16 M NaOH, namely fc' = 81.16 MPa and Ec = 46.903 MPa. The relationship between the two results in a polynomial regression equation y = -11,627x2 + 1870,4x – 28405. The optimum value for Young's dynamic modulus (Ed) is 14 M (427,994 MPa). The relationship fc' with Ed produces a polynomial equation y = 17.953x2 – 424.59x + 338760. The value of Ec compared to Ed varies with NaOH 12 M; 14 AD; 16 AD; and 18 M respectively by 8.7%; 9.0%; 11.1% and 10.8%. Geopolymer concrete 16 M is the best variation because fc' and Ec have the largest value with the smallest . While Ed, v and slump rank second among other NaOH variations.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: Beton Geopolimer, Metode Kering, Modulus Young, Kuat Tekan, Molaritas NaOH. Compressive Strength, Dry Method, Geopolymer Concrete, Molarity of NaOH, Young’s Modulus.
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User: Muhammad Yusril Bastian
Date Deposited: 02 Sep 2021 03:22
Last Modified: 02 Sep 2021 03:22
URI: http://repository.its.ac.id/id/eprint/91621

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