Marina Lopez-Arias

The growing pollution from transportation into the environment has created an urgent need for active mitigation tools. Photocatalytic surface treatments for concrete pavements, such as TiO ₂ -based surface treatments, offer a promising solution by continuously reducing pollutants using solar energy. While previous research has shown that TiO ₂ surface treatments on concrete can reduce CO ₂ concentrations through photoreduction, quantifying the CO ₂ reduction remains necessary to understand their full potential under realistic conditions. This study presents a novel estimation model trained on experimental data from concrete slabs exposed to different light intensities (0, 23, and 100 W/m ² ) and CO ₂ concentrations (6%, 12%, and 100%) to estimate CO ₂ reduction (CDR). Results showed that both higher CO ₂ concentrations and higher light irradiance levels led to greater CDR, with maximum reductions of 0.2 g/m ² per hour under 6% CO _2, 1.6 g/m ² per hour under 12% CO ₂ , and 79.2 g/m ² per hour under 100% CO ₂ , at 100 W/m ² irradiance. Two models were developed: a linear model, assuming CDR increases linearly with light irradiance, and a conservative model, with CDR plateauing at 100 W/m ² . Using real sunlight irradiance and traffic data, the model estimates an annual reduction of 5.8–6.8 kg/m ² with the conservative model, while up to 25.8 kg/m ² with the linear model. Scaling it to 100 km of road, the TiO ₂ surface treatment could remove up to 4.1 M kg of CO ₂ annually in cities like Phoenix and 3.7 M kg in Seattle, demonstrating the potential of this technology for large-scale carbon removal.

In Colombia, low-cost unbonded fiber-reinforced elastomeric isolators made from natural rubber (UN-FREI) and recycled rubber (UR-FREI) have emerged as a solution to mitigate damage in low-rise structures during earthquakes. However, their performance under environmental degradation caused by factors such as carbon dioxide, saltwater, relative humidity, and UV radiation has not been sufficiently studied. These agents can compromise the mechanical properties of rubber, affecting its ability to dissipate energy. This study evaluates the performance of these isolators under different environmental conditions through the initial characterization of rubber, mechanical testing of small-scale prototypes exposed to controlled environments, and seismic analysis of an isolated structure. Modification factors (λ_(ae,max) and λ_(ae,min)) were determined to quantify the impact of degradation on structural behavior. The results indicate that UN-FREI specimens are more sensitive to environmental conditions than UR-FREI specimens, whereas the mechanical properties of UN-FREI small-scale prototypes remain more stable compared to those of UR-FREI. This leads to increased drift, base shear, and demand-to-capacity ratios (DCRs) in the structural analysis. The findings emphasize the need for experimental testing of isolators to establish modification factors that accurately reflect the effects of environmental conditions on structures throughout their service life.

Sugarcane bagasse ash (SCBA), a biomass waste resulting from sugarcane bagasse burning for electricity production, has shown to be a viable alternative option as a partial cement replacement due to its chemical composition and physical properties. Besides, previous research indicates that higher curing temperature may improve the mechanical properties of mixes containing SCBA as cement replacement. However, the environmental assessment of those mixes is lacking in the literature. This study aims to understand how curing temperature impacts the Life Cycle Assessment (LCA) of SCBA as a partial replacement of cement in mortars. An LCA was performed from the extraction of the raw materials to the material production part of the life cycle, including transport. This study shows that the reduction of environmental impact when using SCBA highly depends on the curing temperature. When mortars were cured at 45 °C, the use of SCBA reduced the environmental impact of mortars two times with respect to the reduction at 21 °C (31% reduction when cured at 45 °C vs. 14% at 21 °C, with a 20% replacement). This difference is mainly related to the fact that the higher the curing temperature, the better SCBA mortars perform in terms of strength, thus, net savings of cement required to achieve a given performance are higher. Results indicate that the sustainability of SCBA utilization as a partial replacement of cement will be better when mortar is poured in hot regions or during days with higher ambient temperatures. Likewise, the advantages of using SCBA in terms of sustainability will decrease if the external temperature is low.