Perpustakaan Digital ITB

Roadcel-50 is the brand name of oleophilic micronized cellulose fibres used as a stabilizing agent for bitumen in asphalt mix. The material is produced in Jakarta and has been used on several roads in Indonesia to improve pavement performance. This thesis describes a laboratory investigation of an asphalt concrete mix made with 0.15%, 0.30%, 0.45%, and 0.60% Roadcel-50 by weight of aggregate plus bitumen. For control purposes, a mix without Roadcel-50 was also investigated. Preliminary investigations showed that the effects of adding Roadcel-50 to bitumen were to increase softening point and viscosity and reduce penetration, thereby indicating a reinforcing effect. Marshall analysis of the asphalt concrete mixes showed that the mixes made with 0.15%, 0.30%, 0.45%, and 0.60% Roadcel-50 were satisfactory in terms of Bina Marga or SNI design criteria, and had optimum bitumen contents of, 7.00%, 7.20%, 7.25%, and 7.40%, respectively. The Marshall analysis showed that the mix with 0.30% Roadcel-50 registered the best performance. Specimens of the mixes with Roadcel-50 prepared at optimum bitumen content were investigated using the Marshall immersion, indirect tensile strength and wheel tracking tests. The results of these tests showed that increasing the Roadcel-50 content increased the immersion index and indirect tensile strength and reduced permanent deformation. The asphalt concrete without Roadcel-50 complied with Bina Marga design criteria at an optimum bitumen content of 6.95%. However, the results of the Marshall analysis, Marshall immersion test, indirect tensile strength test, wheel tracking test and calculations of bitumen film thickness indicate a lower performance than that of the mix with Roadcel-50. Difficulty was experienced in preparing mixes at the higher percentages of Roadcel-50. At higher Roadcel-50 content, the material could not be distributed uniformly throughout the mix and this lack of homogeneity contributed to the relatively poor performance of these mixes. Keeping the Roadcel-50 at 0.30% enabled the fibres to be distributed more uniformly throughout the mix thereby enhancing performance.