Estimation and Analysis of Energy Conservation and Emissions Reduction Effects of Warm-Mix Crumb Rubber-Modified Asphalts during Construction Period

Abstract

In order to solve the serious environmental problems caused by the rapid increase in the number of waste tires and unproper storage of waste tires, modifying the asphalt mix for roadway pavement by adding rubber crumb from recycled waste tires is one of the highly effective approach to solve the problem and can achieve the sustainable use of rubber resources. The application of warm-mix crumb rubber-modified asphalt (CRMA) overcomes some issues of the hot-mix CRMA, such as high temperature and high energy consumption. However, there is a lack of estimation methodology for the energy conservation and emission reduction during the production process of warm-mix CRMA. This study develops the estimation models for the evaluation of energy conservation and emissions reduction during different production stages of waste rubber powder, asphalt, CRMA, hot-mix CRMA, and warm-mix CRMA. A list for gas emissions during the mixing and paving process of CRMA mixtures was established through the simulated mixing measurement and paving site measurement. The results show that for each metric ton of CRMA mixture produced, warm mixing can reduce energy consumption by 18~36% and decrease gas emissions during different stages by 15~87% compared to hot mixing. The Evotherm warm-mix CRMA mixture with DAT as warm mix agent (Ev-DAT warm-mix CRMA mixture) is more energy-efficient by saving approximately 108.56 MJ of energy and reducing gas emissions during mixing and paving by at least 32% and 73%, respectively. This model can improves the technical standard of warm-mix CRMA and the energy conservation assessment.Currently, most waste tires are treated as solid waste and are burned or dumped in landfills [4]. In 2007, the quantity of waste tires made into tire-derived fuel in the United States exceeded half of their annual tire yield, while the other 17.2% and 12.2% of waste tires were used as ground rubber materials and civil engineering materials respectively [5]. Waste recycling method that utilizes incineration, pyrolysis, and gasification are generally called waste-to-energy (WTE) processes [6]. This method may not be the best recycling method [7] since it releases a large amount of CO 2 , which causes environmental problems and prevents reutilizing rubber resources even though it converts the waste tires into usable heat, electricity, or fuel. Waste tire treatment consumes natural resources and produces environmental pollution, especially improper treatment results in an unacceptable level of natural resource consumption, environmental pollution, and massive carbon dioxide (CO 2 ) emissions.For saving rubber resources, realizing waste-tire sustainable utilization, and avoiding new pollutions and CO 2 emissions during recycling, researchers have contributed huge efforts. Bhadra et al. [4] processed waste tires into recycled carbon black, which realized rubber resources recycling utilization. Ayanoglu and Yumrutaş [8] adopted catalytic distillation for waste-tire pyrolysis to obtain engine fuel. In the field of civil engineering cons...

Physical, Rheological, and Permanent Deformation Behaviors of WMA-RAP Asphalt Binders

“…This study aimed to investigate Warm Mix Asphalt (WMA) technology with Reclaimed Asphalt Pavement (RAP) addition and assess how these materials interact at the asphalt binder level. The economic benefits and sustainability aspects, considering greenhouse gas reduction policies and the rising global average temperature [20][21][22], make these types of materials promising solutions to be widely adopted in the coming years [29][30][31].…”

Economic and Environmental Benefit Analysis between Crumb Rubber Concrete and Ordinary Portland Cement Concrete

“…With the rapid development of the automobile industry, the number of wasted tires had been soaring annually. A total of 17 million tons of global tire waste was reported in 2009 [1], and it is estimated that 13.5 million tons was produced in mainland China in 2017 [2,3]. As for trends during the same period in the EU, wastages were reported to increase by 250 million every year [4,5].…”

“…Although processed rubber tires from the automobile industry are currently being used in some aspects of civil engineering, such as elastic subgrade (0.24 million tons each year) [8] or rubber asphalt concrete pavement [9], the consumption is no more than 20%. On the contrary, the quantity of waste tires made into tire-derived fuel in the United States (2007) exceeded half of their annual tire yield [3]. Concrete is one of the most important building materials.…”

Rheological Properties of Desulfurized Crumb Rubber Modified Warm Mix Asphalt

“…Honggang Z et al believe that the viscosity of asphalt rubber [5,6] can be reduced appropriately by using desulfurized rubber powder. Further research by Gang et al found that the use of a warm mix agent can not only reduce the viscosity of rubber powder modified asphalt but also reduce the energy consumption during construction and improve the rheological property of rubber powder modified asphalt [6][7][8] .…”