Pengaruh Variasi Perendaman Beton Purun Tikus Terhadap Kuat Tekan dan Kuat Lentur Beton Ani Firda Firda 1 ; Indra Syahrul Fuad 2 1, 2 Jurusan Teknik Sipil, Fakultas Teknik, Universitas Tridinanti Palembang 1 anifirda@univ-tridinanti.ac.id 2 indra.utp@gmail.com ABSTRACT One of the added ingredients of concrete is fiber. The fiber in concrete serves to prevent cracks so as to make concrete more ductile and to increase the tensile strength of concrete. The use of concrete in an aggressive environment is very influential on the strength and value of the compressive and tensile strength of concrete. Concrete structures can be said to be in an aggressive environment when concrete is constantly in the environment of sea water, swamp water, soil, and industrial areas where it contains sulfate, the concrete will be susceptible to sulfate attack which can reduce the durability of concrete and can make concrete become corrosion. Therefore, in this study will examine how much influence the variations in water immersion PDAM Tirta Musi (pH = 7) and swamp water (pH <7) and on the compressive strength and flexural strength with additional purun tikus fibers (eleocharis dulcis) of 0.75% for 28 days. The results showed that the immersion of concrete quality fc '= 20Mpa at 28 days using swamp water (pH = 4.5), can reduce the compressive strength of normal concrete by 11.63%, whereas in purun tikus concrete 0.75% by 4.12%, compared to water immersion concrete of PDAM Tirta Musi (pH = 6.5). Soaking quality fc 'concrete = 20Mpa age of 28 days using swamp water (pH = 4.5), can reduce the flexural strength of normal concrete by 14.8%, while in purun tikus concrete 0.75% by 5.8%, compared to water immersion concrete of PDAM Tirta Musi (pH = 6.5). Keywords: water pH, compressive strength, flexural strength, purun tikus fiber ABSTRAK Salah satu bahan tambah beton ialah serat. Serat dalam beton berfungsi untuk mencegah retak– retak sehingga menjadikan beton lebih daktail dan untuk meningkatkan kekuatan tarik beton. Pemakaian beton pada lingkungan agresif sangat berpengaruh pada keawatan dan nilai kuat tekan dan tarik beton. Struktur beton dapat dikatakan berada pada lingkungan agresif manakala beton terus-menerus berada dalam lingkungan air laut, air rawa, tanah, dan kawasan industri dimana banya terkandung sulfat, beton akan menjadi rentan terhadap serangan sulfat yang dapat mengurangi durabilitas beton dan dapat membuat beton menjadi korosi. Oleh karena itu dalam penelitian ini akan meneliti mengenai seberapa besar pengaruh variasi perendaman air PDAM Tirta Musi (pH=7) dan air rawa (pH<7) dan terhadap kuat tekan dan kuat lentur dengan tambahan serat purun tikus (eleocharis dulcis) sebesar 0.75% selama 28 hari. Hasil penelitian menunjukkan bahwa Perendaman beton mutu fc’ = 20Mpa umur 28 hari menggunakan air rawa (pH=4.5), dapat menurunkan kuat tekan beton normal sebesar 11.63%, sedangkan pada beton purun tikus 0.75% sebesar 4.12%, dibanding beton perendaman air PDAM Tirta Musi (pH=6.5). Perendaman beton mutu fc’ = 20Mpa umur 28 hari menggunakan air rawa (pH=4.5), dapat menurunkan kuat lentur beton normal sebesar 14.8%, sedangkan pada beton purun tikus 0.75% sebesar 5.8%, dibanding beton perendaman air PDAM Tirta Musi (pH=6.5). Keywords: pH air, kuat tekan, kuat lentur, serat purun tikus