Abstract
This research focuses on the production and construction stages of the life cycle analysis (LCA) of asphalt mixtures modified with industrial waste and by-products, based on the quantification of methane (CH4), carbon monoxide (CO) and carbon dioxide (CO2) emissions produced during these processes. A laboratory-designed and calibrated gas measurement system with a microcontroller and MQ sensors is used to compare the emissions (GHG) of a “conventional” asphalt mix with those emitted by waste-modified asphalt mixes (polyethylene terephthalate and nylon fibres) and industrial by-products (copper slag and cellulose ash). The results obtained show that the gases emitted by each type of material can influence the design criteria from an environmental perspective. Methane gas emissions for asphalt mixes made with polymeric materials increase compared to the production phase of a conventional mix (M1) by 21% for PET and 14% for nylon. In contrast, for mixtures made with copper slag and cellulose ash, this emission is reduced by 12%. In addition, the use of copper slag and cellulose ash to replace natural aggregates reduces greenhouse gas emissions by 15% during the production phase and contributes to the creation of photochemical ozone for a shorter period of time. Regarding carbon dioxide emission, it increases considerably for all asphalt mixes, by 26% and 44.5% for cellulose ash and copper slag, respectively. For asphalt mixtures made of polymeric materials, the increase in carbon dioxide emission is significant, 130% for PET and 53% for nylon. In addition, it is noted that for this type of material, not only the emission of the gas must be taken into consideration, but also the time that the volatile particles spend in the atmosphere, affecting climate change and photochemical ozone (smog). The carbon monoxide gases emitted in the production phase of all the asphalt mixes analysed is similar among them.
Highlights
IntroductionOne of the main sectors contributing to the increase of environmental impact in the world is the construction industry
The results on the emission of greenhouse gases during the manufacturing stage of the asphalt mixes with recycled industrial wastes and by-products were obtained through the MQ-4, MQ-7 and MQ-135 sensors calibrated in the laboratory
It can be concluded that in the production phase, emissions of methane gas, carbon dioxide and carbon monoxide are increased and reduced, depending on the materials used in the asphalt mix
Summary
One of the main sectors contributing to the increase of environmental impact in the world is the construction industry. Most of the damage caused is focused on water and energy consumption, emissions of polluting gases into the atmosphere and the exploitation of natural resources [1]. The construction of infrastructures and their subsequent operation depend on the use of large amounts of energy and electricity, which involves the production of elements that help to increase environmental damage [2]. It is relevant to develop new studies and techniques that help to reduce the ecological footprint during
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