Production and characterization of biobinders derived from lignocellulosic biomass for the pavement chain

Author(s)

Maria Jose Castro Alonso

• Document type: Doctoral Thesis
• Press: Lorena.
• Institution: Universidade de São Paulo (USP). Ciência e Engenharia dos Materiais (IFS/EES)
• Defense date: 2023-11-06

Examining board members

Kamilla Vasconcelos Savasini; Leni Figueiredo Mathias Leite; Rajeswari Narayanasamy; Raquel Moraes Puchalski

• Advisor: Kamilla Vasconcelos Savasini; Silvio Silverio da Silva

Abstract

Biobinders are biomaterials produced from renewable sources that offer several advantages compared to petroleum-based asphalt binders. These advantages include reducing the demand for petroleum derivatives and greenhouse gas emissions while utilizing byproducts generated by other industrial processes. Among various substrate alternatives derived from different sectors, lignocellulosic biomass stands out as one of the most promising due to its high availability in Brazil. Assessing the physicochemical properties of biobinders is crucial because these characteristics determine their suitability as potential partial or total substitutes for petroleum-based asphalt binders and their possible use as a rejuvenating agent to recycle aged asphalt binders. In this context, the main objective of this study was to produce and evaluate the physicochemical characteristics of biobinders derived from various lignocellulosic biomass sources for pavement applications. Different biobinders derived from pine wood, sugarcane bagasse (SB), sugarcane straw (SS), and rice husk (RH) were characterized. Biobinders derived from pine wood consist of commercial biomaterials, while those derived from SB, SS, and RH were obtained through slow pyrolysis as part of the present dissertation. One of the main challenges in using biobinders for pavement applications is their high moisture content and oxygenated compounds, primarily derived from the carbohydrate fraction of lignocellulosic biomass. Therefore, to obtain materials with better characteristics, SB, SS, and RH were also subjected to acid pretreatment to obtain raw materials with lower carbohydrate content (cellulignin) to produce biobinders through slow pyrolysis. The physicochemical characterization of biobinders mainly involved pH, water content, elemental analysis, GC-MS, FTIR, TGA/DTG, and linear viscoelastic characterization. The results were then compared to the physicochemical analysis of a petroleum-derived asphalt binder (AC 30/45) widely used on Brazilian highways. The chemical analysis revealed that all biobinders exhibited higher water content, pH values 3, and a distinctly different composition than AC 30/45. Generally, biobinders derived from pine wood were composed of saturated and monounsaturated fatty acids, while those derived from SB, SS, and RH were primarily phenolic compounds. AC 30/45, on the other hand, consisted mainly of hydrocarbons and acids. FTIR, thermal, and rheological analysis suggested that biobinders exhibited more elastic behavior and were more susceptible to aging than AC 30/45. FTIR and dosage analysis revealed that biobinders derived from pretreated SB and RH showed promising results as rejuvenator components for recycling aged AC 30/45. The research highlights the substantial influence of biomass source, reactor configuration, and biobinder production method on the rheological properties of the final product. It emphasizes the need to adapt the process to suit the specific characteristics of the biomaterials produced. These results suggested that biomaterials still face some challenges as substitutes for petroleum-based asphalt binders. However, in future studies, these biobased materials can be evaluated as rejuvenating agents or partial/total replacements in warm mixtures for the surface layers of roads. (AU)

• FAPESP's process: 19/14931-2 - Use of lignocellulose biomass in the development of biobinder for the pavement network
• Grantee: Maria Jose Castro Alonso
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)