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TiO2 nanoparticles influence on the environmental performance of natural and recycled mortars: A life cycle assessment
Environmental Impact Assessment Review ( IF 6.122 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.eiar.2020.106430
Carlos Moro , Vito Francioso , Molly Schrager , Mirian Velay-Lizancos

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.

中文翻译:

TiO2 纳米颗粒对天然和再生砂浆环境性能的影响:生命周期评估

摘要 世界气象组织最近报告说,温室气体达到了自 3-5 百万年前以来的最高水平。持续上升会导致严重后果,例如气温上升、生物死亡或水污染。水泥与这些水平相关,因为其生产占全球二氧化碳排放量的 8% 左右。为了提高胶结材料的环境性能,可以采用不同的方法,例如,再利用再生骨料 (RA) 等废物材料或添加 TiO2 纳米颗粒,因为其在使用寿命期间具有积极作用。然而,没有发现研究纳米二氧化钛添加对再生砂浆在环境影响方面的影响。最后,这项研究的主要目的是评估二氧化钛纳米粒子在由天然或再生骨料制成的砂浆中的可持续性。研究了具有不同百分比的纳米 TiO2 替代(0%、0.5%、1%、2%,按水泥重量计)和 RA 替代(0%、50%、100%)的 12 种混合物。进行了以材料生产(从摇篮到大门)为重点的生命周期评估。使用的功能单元 (FU) 是具有给定抗压强度的 1 立方米砂浆。对配合比设计进行了修改,以满足 FU 中定义的固定强度。在全球变暖潜势方面,当添加 0.5% 的纳米二氧化钛时,具有 RA 的砂浆减少了对环境的影响。考虑到废物的产生和自然资源的枯竭,在用 RA 对砂浆的可持续性评估中起着至关重要的作用。此外,当在 FU 中考虑抗压强度系数时,由于需要更多的水泥,RA 增加了 CO2 排放总量。最后,尽管纳米 TiO2 使用从摇篮到门的方法有明显的有害影响,但由于它们在使用寿命期间的影响,这些纳米颗粒可以极大地提高环境性能。
更新日期:2020-09-01
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