Increasing traffic requires durable and low-noise road surfaces. Urban residents complain about excessive traffic noise that leads to an unhealthy environment. Understanding techniques to produce durable, low-noise pavement has led to the development of rubberized concrete block pavement (RCBP) and rubberized asphalt concrete pavement (RACP). The chapter examines morphology and chemical properties of waste tyre rubber using FESEM, XRF, and TGA/DTA. Authors discuss characteristics of RCPB and RACP and conclude application of RCBP and RACP can lower traffic noise.
TopIntroduction
In view of a conventional waste management system, waste tyres are basically either disposed in the landfill or burned. Tyre stockpiles caused severe health problem to human due to mosquito, vermin, and rats breeding. Fire hazard from the tyre burning activity also can cause uncontrollable burning and air pollution. However, tyre disposal and burning in landfills are banned in most countries (Martínez et al., 2013). According to Shah (2006), the current ‘‘conservation of natural resource concept’’, i.e. the reuse (retread) first, then reuse of rubber prior disposal, does not accommodate the ever-increased dumping of tyres. Due to the high cost of legal disposal for tyres, illegal dumping may increase. Disposal of tyres is becoming more expensive, while this trend is likely to continue as landfill spaces become insufficient. Tyres take up landfill space.
The challenge of scrap tyre management arises mainly from the technical and commercial issues relating to tyres both as a product and as a waste. What is tyre? Tyres are made of materials including synthetic and natural rubber, textiles, steel, carbon black, aromatic extender oils and various chemical additives, which are “vulcanised” at a high temperature during the manufacturing process (Chemsain, 2011). The main components of car and truck tyre as shown in Figure 1 is particularly a stable product that requires a great energy to properly break the material down to useful product. In this chapter, we’ll look into the component of a tyre, the chemical and physical properties, waste tyre management, and waste tyre application in pavement industry.
Figure 1. Source: https://kitchendecor.club/files/radial-tire-cross-section.html TopPyrolysis Of Waste Tyres
Waste tyre pyrolysis is an endothermic process whereby the waste tyres were exposed and absorbed the surrounding heat provided in a reactor vessel containing an oxygen-free atmosphere. For the reactor, Lopez et al. (2017) suggest using conical spouted bed reactor (CSBR) that perform adequate pyrolysis for different waste materials. In addition, Kwon et al. (2015) recommend the utilization of CO2 as the pyrolysis reaction medium. According to Miranda et al. (2013), WTR pyrolysis leads to the formation of non-condensable compounds, light liquids, and solid products. Similar observation found by Martínez et al. (2013) where 40% of the pyrolysis by-product is in the form of a solid fraction (char or carbon black and steel) and another 60% removed as a volatile fraction. These vapours can be burned directly to produce power or condensed into an oily type liquid, generally used as a fuel. Some molecules are too small to condense. They remain as a gas which can be burned as fuel. Figure 2 shows the primary and secondary products of WTR pyrolisis observed by Akhil et. al. (2018).