Скачать или смотреть Assessing the Impact of TiO2 Nanoparticles on the Environmental Performance of Mortars with RCA

Presented By: Carlos Moro, Texas State University

Description: 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.