TiO2 nanoparticles influence on the environmental performance of natural and recycled mortars: A life cycle assessment |
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| Institution: | 1. Department of Architecture (D’ARCH), Polytechnic School, University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo, Italy;2. Department of Materials and Ceramic Engineering/CICECO–Aveiro Institute of Materials, University of Aveiro, Campus Universitàrio de Santiago, 3810-193 Aveiro, Portugal;3. Slovenian National Building and Civil Engineering Institute, Dimi?eva 12, SI-1000 Ljubljana, Slovenia;1. Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA;2. Grupo de Construcción, Centro de Innovación Tecnológica en Edificación e Ingeniería Civil (CITEEC), E.T.S. Ingenieros de Caminos, Canales y Puertos, Universidade da Coruña, Campus de Elviña, s/n, 15071 A Coruña, Spain;3. Department of Mechanical Engineering, The University of Texas at San Antonio, TX 78249, USA;1. Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA;2. Grupo de Construcción, Centro de Innovación Tecnológica en Edificación e Ingeniería Civil (CITEEC), E.T.S. Ingenieros de Caminos, Canales y Puertos, Universidade da Coruña, Campus de Elviña, s/n, 15071 A Coruña, Spain;3. ISISE, University of Minho, Department of Civil Engineering, Campus of Azurém, Guimarães, Portugal;1. Structures Division, Department of Civil Engineering, National Institute of Technology, Warangal, India;2. CERis-ICIST, Instituto Superior de Engenharia de Lisboa (ISEL - IPL), R. Conselheiro Emídio Navarro, 1, 1959-001 Lisbon, Portugal;3. CERis-ICIST, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal;1. Department of Civil and Environmental Engineering (CEE), The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong;2. Department of Civil and Industrial Engineering, Pontificia Universidad Javeriana Cali, Calle 18 # 118-250, Av. Cañas Gordas, Cali, Colombia |
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| Abstract: | The World Meteorological Organization has recently reported that greenhouse gases have reached their highest level since 3–5 million years ago. A continuing rise would cause serious consequences e.g., rising temperatures, death of living beings, or water pollution. Cement is associated with those levels since its production encompasses around 8% of global CO2 emissions. To increase the environmental performance of cementitious materials, different approaches could be followed, for instance, the reuse of waste materials such as recycled aggregate (RA) or the addition of TiO2 nanoparticles due to its proactive effect during service life. However, no research has been found that examined the effect of nano-TiO2 addition on recycled mortars in terms of environmental impact. Consequently, the main objective of this research is to evaluate the sustainability of TiO2 nanoparticles in mortars made with either natural or recycled aggregate. Twelve mixtures with different percentages of nano-TiO2 substitution (0%, 0.5%, 1%, 2% by the weight of cement) and RA replacement (0%, 50%, 100%) were studied. A life cycle assessment focused on material production (cradle-to-gate) was performed. The functional unit (FU) used was 1 m3 of mortar with a given compressive strength. The mix design was modified to meet the fixed strength defined in the FU. In terms of global warming potential, mortars with RA reduced the environmental impact when 0.5% of nano-TiO2 was added. Considering waste generation and depletion of natural resources play a crucial role in the sustainability assessment of mortars with RA. Furthermore, when the compressive strength factor was considered in the FU, RA increased the total CO2 emissions due to the higher amount of cement needed. Finally, despite the apparent harmful effect of nano-TiO2 using a cradle-to-gate approach, these nanoparticles could highly enhance environmental performance due to their effects during service life. |
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