Enhancing Buton asphalt performance using ι-carrageenan: A sustainable solution for pavement durability

Indonesia has abundant Buton asphalt, but its use in roads is limited due to its comparatively lower mechanical performance compared to petroleum-based asphalt. To address this, the present study investigated dosages ranging from 0 to 12 % of ι-carrageenan, a natural polymer derived from Eucheuma denticulatum known for its high sulfate content and strong gelling properties compared to other bio-based additives. The experimental methodology involved synthesizing ι-carrageenan through an alkaline extraction process and incorporating it into Buton asphalt concrete-wearing course (AC-WC Asb) mixtures. Marshall tests and Indirect Tensile Stiffness Modulus (ITSM) tests were conducted to evaluate the mechanical performance. Additionally, ι-carrageenan was characterized using Fourier-transform infrared spectroscopy (FTIR) to identify functional groups and thermogravimetric analysis (TGA) to assess thermal stability. Results showed that an 8.5 % ι-carrageenan significantly enhanced the asphalt mixture's performance: stability rose by 2.68 %, flow by 17.88 %, and void parameters (VMA, VIM, VFB) were optimized within specifications. The improved flow at higher ι-carrageenan content reinforced cracking resistance, contributing to better durability under traffic loads. Furthermore, the incorporation of ι-carrageenan enhances the stiffness modulus of the mixture, thereby augmenting its resistance to permanent deformation, particularly in terms of rutting. TGA revealed multi-stage thermal degradation but confirmed stability up to ∼250 °C, ensuring compatibility with hot mix asphalt processes. However, excessively high ι-carrageenan concentrations diminished stability and Marshall Quotient, indicating that 8.5 % provides an optimal balance. This research highlights ι-carrageenan's potential as a sustainable, bio-based additive to enhance Buton asphalt's durability and mechanical properties, promoting eco-friendly infrastructure by utilizing local seaweed resources.