Studi Komparatif Kuat Tekan Beton Normal dan Beton dengan Silica Fume dan Natrium Klorida pada Pasir Berkadar Lumpur >5%

Abstract

Abstract: Concrete is a construction material widely used in buildings, roads, bridges, and dams. According to standards, sand used in concrete mixtures must have a silt content of less than 5%. High silt content reduces concrete quality by weakening the bond between the cement paste and the aggregates. A shortage of high-quality sand has prompted the use of sand with high silt content, supplemented by silica fume and sodium chloride (NaCl). This study aims to analyze the effects of high-silt sand and the addition of silica fume and NaCl on the compressive strength of concrete. An experimental method was employed using cylindrical specimens with a diameter of 15 cm and a height of 30 cm. Mixture variations included normal concrete, concrete with high-silt sand, and combinations of NaCl (1%, 3%, and 5%) with silica fume (5%, 10%, and 15% of cement weight). Compressive strength testing was conducted at 28 days using a Compression Testing Machine (CTM). The results showed that the compressive strength of normal concrete was 20.27 MPa, whereas that of concrete with high-silt sand was 12.53 MPa, representing a 38.18% decrease. The highest compressive strength of 15.12 MPa was achieved with a mixture of 1% NaCl and 5% silica fume, an increase of 20.63% compared to concrete without additives. Overall, 1% NaCl yielded the best results, while silica fume did not demonstrate a consistent effect.

Abstrak: Beton merupakan material konstruksi yang banyak digunakan pada bangunan gedung, jalan, jembatan, dan bendungan. Menurut standar, pasir yang digunakan dalam campuran beton harus memiliki kadar lumpur kurang dari 5%. Kadar lumpur yang tinggi menurunkan mutu beton karena melemahkan ikatan antara pasta semen dan agregat. Keterbatasan pasir berkualitas mendorong pemanfaatan pasir berkadar lumpur tinggi dengan penambahan silica fume dan natrium klorida (NaCl). Penelitian ini bertujuan menganalisis pengaruh pasir berkadar lumpur tinggi serta penambahan silica fume dan NaCl terhadap kuat tekan beton. Penelitian menggunakan metode eksperimen dengan benda uji silinder berdiameter 15 cm dan tinggi 30 cm. Variasi campuran meliputi beton normal, beton dengan pasir berkadar lumpur tinggi, serta kombinasi NaCl 1%, 3%, dan 5% dengan silica fume 5%, 10%, dan 15% dari berat semen. Pengujian kuat tekan dilakukan pada umur 28 hari menggunakan Compression Testing Machine (CTM). Hasil penelitian menunjukkan kuat tekan beton normal sebesar 20,27 MPa, sedangkan beton dengan pasir berkadar lumpur tinggi sebesar 12,53 MPa atau menurun 38,18%. Kuat tekan tertinggi sebesar 15,12 MPa diperoleh pada campuran NaCl 1% dan silica fume 5%, meningkat 20,63% dibandingkan beton tanpa bahan tambah. Secara keseluruhan, NaCl 1% memberikan hasil terbaik, sedangkan silica fume tidak menunjukkan pengaruh yang konsisten.