Calculation of the ecological footprint of concrete. A tool for sustainable design

Abstract

Concrete is the most used construction material in the world, however, its use poses severe environmental costs stressing the amount of energy consumed and CO2 released during its production. It is proposed the incorporation into concrete, as a replacement of coarse aggregate, a multilayer plastic residue from the CReSE. (Waste Collection Company of Cordoba) which aim is to reduce its Ecological Footprint (EF). In order to achieve this, the materials were selected and characterized to be used. It was also decided the dosage of concrete pattern (without incorporation of plastic) and concretes with replacement of coarse aggregate by multilayer plastic. The experimental stage included trials in fresh and hardened to verify its properties. Then, a literature research relating to the use of concrete (m³) per Cordoba in recent years was made, and we proceeded to define a simplified calculation method of concrete EF. The flows of matter and energy consumed and emitted at different times of development of concrete were quantified. Finally, the analysis was performed and the results of conventional concrete EF with EF concrete with plastic were compared. The results confirm that the materials are the most influential part of the total footprint of concrete representing nearly 85%, in the province of Córdoba HE corresponding to the materials is 9 ha / person / year being the total of 10.8 ha / person / year. In mining activities, dredging, etc. of sand and gravel, it is necessary to use heavy machinery capable of undertaking these tasks, which results in considerable fuel consumption with corresponding CO2 emissions into the atmosphere. The highest percentage of emission is given in the process of calcinations of the limestone to obtain clinker. However aggregate extraction represents 11% of the EF materials. To conclude, it is considered that causing the replacement of coarse aggregate by plastic waste, there is a decrease of EF waste concrete, in comparison to conventional concrete. This work provides an example of applying a tool to analyze the use of different materials and resources in order to predict which will lead to greater eco-efficiency, as it allows to know in advance the most sustainable option in the design phase of concrete.