**1. Introduction**

#### **1.1. General introduction**

Bio-materials that are used as binders in asphalt mixtures are termed "bio binders" [1]. The interest on using bio-binders in pavement engineering has significantly grown over the last decades due to the increasing scarcity of raw materials and environmental concerns about the use of non-recoverable natural resources.

Common alternative binders include engine oil residue, bio-binder, soybean oil, palm oil, fossil fuel, swine waste, and materials from pyrolysis [2]. Chemical compositions of the majority of these alternative binders are similar to those of unmodified asphalt binders (e.g. Resin, saturates, aromatics, and asphaltene) [3]. On the other hand, tests indicate the wide variability in the properties of alternative binders. Also, the chemical modification mechanism for asphalt with alternative binders depends clearly on the unmodified asphalt and is consequently not well understood [4, 5]. For energy sustainability, environment-friendly materials and an urgent need for infrastructure rehabilitation that more research is needed to evaluate the alternative binders for use in asphalt modification. The alternative binders should have moisture resistance and good aging characteristics [6].

**3. Materials used for the production of bio-binder**

Elemental composition (H, C, O, N) (wt %) (5.5–7.0, 54–58, 35–40, 0–0.2)

**Physical property Value** Percent of moisture (wt %) 15–30 pH 2.5 Specific gravity 1.2

Distillation residual (wt %) Up to 50 Viscosity @500°C (pa) 40–100

**Table 1.** Typical characteristics of wood-based bio-oils.

Bio-Oil is the liquid produced from the rapid heating of biomass in a vacuum condition [17]. There are many advantages for bio-oils over asphalt from crude oil as they are environmentfriendly, renewable, present a great economic opportunity, and provide energy security.

Asphalt Modified with Biomaterials as Eco-Friendly and Sustainable Modifiers

http://dx.doi.org/10.5772/intechopen.76832

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To obtain more gasoline and other liquid fuels, the quality of the bio-oil is improved by using processes such as thermal cracking and hydrogenation [16, 17]. Upon fractionation, the light hydrocarbon fraction can be used as fuel. The remaining heavy residue called bio-binder can

Fast pyrolysis is a thermal decomposition process that requires a high heat transfer rate to the biomass particles and a short vapor residence time in the reaction zone [8], which is a hightemperature process for the production of vapors, aerosols and some coal-like char where biomass is quickly heated in the vacuum and then decomposes. The dark brown mobile fluid (bio-oil) is formed after cooling and condensation of these vapors and aerosols. When organic matter is biomass, consisting of biopolymers (such as cellulose, hemicelluloses, and lignin), the oils produced are called bio-oils. Generally, fast pyrolysis is used to obtain high-grade biooil. Fast pyrolysis processes produce 60–75 wt% of liquid bio-oil, 15–25 wt% of solid char, and 10–20 wt% of non-condensable gases. Fast pyrolysis initially starts with slow heating rates, and then involves a rapid heating rate of the biomass, that can reach up to 300°C/min, but not

Fast pyrolysis design variables include, but are not limited to the following ones reported by [8]: feed moisture content, particle size, pretreatment, reactor configuration, heat supply, heat

**3.1. Bio-oil**

*3.1.1. Bio-oil sources and production*

*3.1.1.1. Thermochemical liquefaction*

be used as an asphalt binder modifier.

*3.1.1.2. Pyrolysis process*

as fast as flash pyrolysis.
