Serabut kelapa sudah banyak digunakan untuk bahan industri. Dalam penelitianini serabut kelapa digunakan sebagai bahan tambah pada campuran beton semenuntuk stabilisasi lapis pondasi bawah (sub-base) pada konstruksi jalan. Namunserabut kelapa yang digunakan dalam penelitian ini adalah serabut kelapa sisabahan industri. Penambahan serabut kelapa ini dengan persentase 2,5%, 5%,7,5%, 10% terhadap berat semen dan panjang serat 2,5 cm. Pengujian penelitianini meliputi: kuat tekan, kuat tarik belah, kuat lentur. Komposisi bahan pengikatsemen 97,5% + serabut kelapa 2,5% dalam pengujian kuat tekan memiliki nilailebih besar 17,68% (fc’ 130,687 kg/cm2) dibanding komposisi bahan pengikatsemen 100% (fc’ 107,569 kg/cm2), dan dalam pengujian kuat lentur memiliki nilailebih besar 8,81% (15,90 kN) dibanding komposisi bahan pengikat semen 100%(14,5 kN). Campuran serabut panjang 2,5 cm dengan kadar serabut 2,5% terhadapberat semen dapat meningkatkan kuat tekan dan kuat lentur tetapi terjadipenurunan untuk kuat tarik belah.

---

Coconut fibers are already widely used for industrial materials. In this study,coconut fiber is used as a material added to the concrete mix cement forstabilization of the sub-base layer for road construction. But coconut fibers in thisstudy were processed coconut fibers of the rest of the industrial process. Theaddition of coconut fibers with a percentage of 2.5%, 5%, 7.5%, 10% of theweight of cement and fiber length of 2.5 cm. Test methods in this study include:compressive strength, split tensile strength, and flexural strength. Cement concretemixtures in this study is the cement composition of 97.5% + 2.5% coconut fiber.The compressive strength of concrete cement showed greater 17.68% (fc '130.687kg/cm2) than cement binder composition 100% (fc' 107.569 kg/cm2). and theflexural strength testing has had a greater value 8.81% (15.90 kN) than the cementcomposition 100% (14.5 kN). Coconut fibers with a length of 2.5 cm and a fibercontent of 2.5% of the weight of cement can increase the compressive strengthand flexural strength but a decrease for split tensile strength.