Investigation of Stone Mastic Asphalt (SMA) with Coconut Fiber and Liquefied Plastic Garbage as Stabilizing Agents

The growing problem in solid wastes generated from the coconut fiber and plastic garbage is one of the many problems confronted now by many LGUs in one of the provinces in the Philippines. Different fibers and additives from PET has separately showed significant positive impact in SMA however the significant impact of local untreated coconut husk fiber in SMA asphalt mixture with liquefied PET bottle needed to further investigate. Physical properties such as air voids, VMA and VFA were conducted on conventional and experimental mixture, where 0.30%, 0.35%, & 0.40% experimental mixture passed the DPWH standard requirement. Marshall Stability and Flow of the experimental mixture was compared with DPWH standard value to determine the optimum fiber content of SMA with added 6% PET bottles with respect to the weight of the bitumen. Upon testing, it was observed that 0.30%, 0.35% and 0.40% passed the DPWH Standard but the design mix with 0.45% coconut fiber failed in both physical and mechanical property tests. It was concluded that 0.40% was the optimum fiber content using Marshall Design Mix method mentioned above with 4.50% higher index retained strength than the conventional mix. Furthermore, it also concluded that the coconut fiber showed significant effect in terms of Stability with a p-value of 0.013 while on Flow it showed non-significant effect at p-value of 0. 108. Thus, it is recommended that both waste materials from coconut and plastic garbage can be used as a replacement for conventional stabilizer materials used for stone mastic asphalt.