Pemanfaatan limbah serutan bambu petung menjadi balok semen komposit merupakan solusi agar limbah tersebut bernilai ekonomi. Balok semen partikel dapat dijadikan bahan konstruksi seperti batako, tiang dan kusen yang ramah lingkungan, lebih ringan, dan tahan retak dibandingkan beton. Selain itu, tahan api dan rayap jika dibandingkan kayu solid. Variasi kerapatan nominal diperlukan untuk mengetahui kekuatan optimum yang dihasilkan dari setiap kerapatan balok. Faktor lain yang mempengaruhi produk semen yaitu rasio semen : partikel, yang secara umum peningkatan rasio dapat meningkatan sifat fisika serta mekanika. Penelitian ini bertujuan untuk menganalisis pengaruh kerapatan dan rasio semen : partikel terhadap sifat fisika dan mekanika balok semen partikel serutan bambu petung. Penelitian ini menggunakan rancangan acak lengkap dengan dua faktor, yaitu variasi kerapatan nominal (0,6 ; 0,8 ; dan 1 g/cm 3 ) dan rasio semen : partikel (2:1 dan 3:1). Pembuatan balok semen partikel menggunakan ukuran serutan lolos saringan 0,2 x 0,2 cm dan katalisator MgCl2 3% dari berat semen. Pengujian kualitas balok semen partikel meliputi sifat fisika (kadar air, kerapatan, penyerapan air, pengembangan tebal) dan sifat mekanika (pengurangan tebal akibat tekanan 3 kg/cm 2 , modulus patah, dan modulus elastisitas) berdasarkan standar DIN 1101. Hasil penelitian menunjukkan interaksi faktor kerapatan nominal dan rasio semen : partikel berpengaruh sangat nyata terhadap pengembangan tebal balok, dengan nilai terendah 0,177% pada kerapatan 1 dan rasio 3:1. Peningkatan kerapatan nominal (dari 0,6 ke 1 g/cm 3 ) berpengaruh sangat nyata terhadap peningkatan kadar air, kerapatan aktual, modulus patah dan modulus elatisitas serta penurunan nilai penyerapan air. Rasio semen : partikel memberikan pengaruh nyata terhadap nilai kerapatan aktual, semakin tinggi rasio (dari 2:1 ke 3:1) maka kerapatan aktual balok semakin meningkat. Sifat balok semen partikel serutan bambu petung dengan kombinasi terbaik diperoleh pada kerapatan nominal 1 g/cm 3 dan rasio 3 semen : 1 partikel, dengan nilai kadar air 14,11%, kerapatan aktual 1,318 g/cm 3 , penyerapan air 13,51 %, pengembangan tebal 0,177 %, pengurangan tebal 2,435%, modulus patah 41,83 kg/cm 2 , dan modulus elastisitas 29.098 kg/cm 2 . Sifat mekanika balok semen serutan bambu lebih tinggi dibandingkan beton, tetapi masih lebih rendah dari kayu solid.

The utilization of bamboo petung waste in the form of shaving as cement beam composite is an economic solution. Cement beam particle could be used as construction materials such as bricks, column and frame that are environmentally friendly, lighter, and crack resistant than concrete. Furthermore, fire and termite resistant than solid wood. The variation of nominal density is needed to investigate the optimum strength resulted by each beam density. The other factor that influence is cement : particles ratio which in general their increase will be followed by increase of physical and mechanical properties of cement product. This research aims to analyze the effect of density and cement : particles ratio to the physical and mechanical properties of cement beam made from bamboo petung shavings. This research used completely randomized design with two factors which were density nominal variation (0,6 ; 0,8 ; and 1 g/cm 3 ) and cement : particles ratio (2:1 and 3:1). Beam was made by particles passing 0,2 x 0,2 cm of sieve size and catalyst of 3% MgCl2. The quality test of cement beam particle included physical (moisture content, actual density, water absorption, thickness swelling) and mechanical (thickness reduction on 3 kg/cm² of pressure, modulus of rupture and modulus of elasticity) test in accordance to DIN 1101. The result showed that interaction between nominal density and cementparticles ratio significantly influenced to the thickness swelling of beam, with the lowest value of 0,177% at a density of 1 and the ratio of 3:1. The increase of nominal density (from 0,6 to 1 g/cm 3 ) influenced significantly to increased value of moisture content, actual density, modulus of rupture and elasticity, and the decrease value of water absorption. Cement-particle ratio gave significant influence to the value of actual density, the increase of ratio (from 2:1 to 3:1) will also increase the actual density. The properties of cement beam made from bamboo petung shaving in best combination were obtained from 1 g/cm 3 of nominal density and 3 particles: 1 cement in ratio with 14. 11% of moisture content, 1.318 g/cm 3 of actual density, 13.51% of water absorption, 0.177% of thickness swelling, 41.83 kg/cm 2 of rupture modulus and 29,098 kg/cm 2 of elasticity modulus. Mechanical properties of cement beam bamboo petung shavings is higher than concrete, but their mechanical lower than solid wood.

Kata Kunci : Balok semen, kerapatan, rasio semen : partikel, bambu petung