Putri, Yossa Hasanah (2025) Studi Eksperimental Respons Lentur Dan Geser Balok Beton Bertulang Pada Beton Teraktivasi Alkali (Alkali-Activated Concrete) Dengan Perawatan Suhu Lingkungan. Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Alkali-activated Concrete (AAC) merupakan inovasi beton ramah lingkungan yang memanfaatkan limbah industri, seperti Fly Ash (FA) dan Ground Granulated Blast Furnace Slag (GGBFS) sebagai bahan pengikat utama. Penggunaan AAC mengurangi penggunaan semen portland sekaligus mengurangi dampak lingkungan yang diakibatkan oleh produksi semen konvensional. Penelitian terdahulu menunjukkan bahwa beton ACC memiliki kuat tekan sebanding dengan konvensional, namun pembahasan perilaku lentur dan geser masih terbatas. Oleh karena itu, penelitian ini bertujuan untuk menganalisis respons lentur dan geser balok AAC melalui studi eksperimental dengan metode perawatan suhu lingkungan. Material penyusun beton dianalisis melalui X-Ray Fluorescence (XRF). Mutu beton rencana pada penelitian ini adalah 30 MPa. Pengecoran dilakukan dengan metode one-part mixing untuk memastikan homogenitas campuran. Kuat tekan dan modulus elastisitas diuji melalui silinder 100 x 200 mm pada umur 28 hari. Evaluasi perilaku mekanis terhadap mode kagagalan lentur dan geser menggunakan metode three-point bending. Pengujian mode kegagalan lentur dan geser dilakukan pada enam balok berukuran 150 x 250 x 1600 (mm) dengan konfigurasi tulangan geser yang berbeda-beda. Spesimen pengujian terdiri atas empat balok beton bertulang AAC dan dua balok beton bertulang Ordinary Portland Cement (OPC). Perkembangan retak dan derfomasi balok selama proses pembebanan menggunakan metode Digital Image Correlation (DIC) dengan perangkat lunak Ncorr MATLAB. Hasil penelitian menunjukkan bahwa balok AAC memiliki respons lentur dan geser yang sangat kompetitif dibandingkan dengan balok beton normal. Balok AAC dengan tulangan sengkang menunjukkan kapasitas lentur dan geser yang tinggi, dengan tulangan lentur mencapai fase leleh penuh dan memasuki regangan plastis lanjutan, mengindikasikan perilaku daktail yang dominan. Balok AAC dengan tulangan geser, seperti AAC-FC (Ø8-100 mm), menunjukkan kapasitas lentur mencapai 44.48 kN dan kapasitas geser sebesar 68.44 kN. Pada balok ini, regangan tulangan lentur mencapai 3.3 x 10⁻² mm/mm, jauh melampaui regangan leleh baja teoritis yaitu 2.21 x 10⁻³ mm/mm, mengindikasikan leleh penuh dan perilaku daktail yang dominan. Sebagai perbandingan, balok NC-FC (Ø8-100 mm) mencapai kapasitas lentur tertinggi 48.19 kN dan kapasitas geser 74.13 kN, dengan regangan lentur mencapai 1.51 x 10⁻² mm/mm, juga menunjukkan leleh penuh. Mode kegagalan utama pada balok AAC dengan sengkang didominasi oleh mekanisme lentur dan kombinasi yang daktail, ditandai dengan kemampuan mempertahankan beban pada deformasi pasca-puncak yang besar. Sebaliknya, balok tanpa sengkang (AAC-DT dan NC-DT) menunjukkan kapasitas yang jauh lebih rendah masing-masing Mn Test 30 kNm, Vn Test 46 kN dan mode kegagalan getas dengan defleksi untuk AAC-DT 9.68 mm dan NC-DT 6.88 mm, serta tulangan lentur yang belum mencapai leleh maksimum yaitu 1.72 x 10⁻³ mm/mm untuk AAC-DT. Peningkatan kapasitas geser signifikan hingga 46.7% diamati pada balok AAC dengan sengkang dibandingkan tanpa sengkang, menegaskan peran krusial tulangan geser. Penggunaan DIC terbukti efektif dalam mendeteksi retak mikro dan memberikan pengukuran lebar retak yang lebih rinci dibandingkan metode manual. Hal ini menunjukkan bahwa AAC memiliki karakteristik daktail dan ketahanan deformasi yang baik, sehingga layak dipertimbangkan sebagai alternatif material struktural pada konstruksi ramah lingkungan. Penelitian ini memberikan kontribusi terhadap pengembangan teknologi beton berkelanjutan di Indonesia serta membuka peluang riset lanjutan terkait ketahanan jangka panjang material AAC terhadap pengaruh lingkungan.
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Alkali-activated Concrete (AAC) is a green concrete innovation that utilizes industrial waste, such as Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS), as the primary binding materials. AAC utilizes industrial by-products to reduce Portland cement consumption and minimize the environmental impact of cement production. Previous research indicates that AAC concrete achieves compressive strength comparable to conventional concrete; however, studies on its flexural and shear behavior are still limited. Therefore, this study aims to analyze the flexural and shear response of AAC beams through an experimental approach under ambient curing conditions. The concrete materials were analyzed by X-Ray Fluorescence (XRF). The concrete compressive strength for the specimen is design with 30 MPa concrete. The casting process utilized the one-part mixing method to ensure a homogeneous mixture. Compressive strength and elastic modulus were tested using 100 x 200 mm cylinders at 28 days. The evaluation of mechanical behavior in terms of flexural and shear failure modes was conducted using the three-point bending method. The flexural and shear failure tests were conducted on six beams measuring 150 x 250 x 1600 mm with different reinforcement configurations. The specimens included four AAC-reinforced concrete beams and two OPC-reinforced concrete beams. The crack development and beam deformation during the loading process were analyzed using the Digital Image Correlation (DIC) method with Ncorr MATLAB software. The research results show that AAC beams have highly competitive flexural and shear responses compared to normal concrete beams. AAC beams with shear reinforcement exhibit high flexural and shear capacities, with flexural reinforcement reaching full yield and entering advanced plastic strain, indicating dominant ductile behavior. AAC beams with shear reinforcement, such as AAC-FC (Ø8-100 mm), exhibit a flexural capacity of 44.48 kN and a shear capacity of 68.44 kN. In these beams, the flexural reinforcement strain reaches 3.3 x 10⁻² mm/mm, far exceeding the theoretical steel yield strain of 2.21 x 10⁻³ mm/mm, indicating full yielding and dominant ductile behavior. For comparison, the NC-FC beam (Ø8-100 mm) achieves the highest bending capacity of 48.19 kN and shear capacity of 74.13 kN, with bending strain reaching 1.51 x 10⁻² mm/mm, also indicating full yielding. The primary failure mode in AAC beams with stirrups is dominated by bending mechanisms and ductile combinations, characterized by the ability to maintain load under significant post-peak deformation. In contrast, beams without stirrups (AAC-DT and NC-DT) exhibit significantly lower capacities, with Mn Test 30 kNm, Vn Test 46 kN, and brittle failure mode with deflections of 9.68 mm for AAC-DT and 6.88 mm for NC-DT, as well as flexural reinforcement that had not reached maximum yield, 1.72 x 10⁻³ mm/mm for AAC-DT. A significant increase in shear capacity of up to 46.7% was observed in AAC beams with stirrups compared to those without stirrups, confirming the crucial role of shear reinforcement. The use of DIC was proven effective in detecting microcracks and providing more detailed crack width measurements compared to manual methods. This indicates that AAC possesses good ductile characteristics and deformation resistance, making it a viable alternative structural material for environmentally friendly construction. This study contributes to the development of sustainable concrete technology in Indonesia and opens opportunities for further research on the long-term durability of AAC materials under environmental influences.
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