Search Results (6)

Concrete coating technology is a key measure that enhances the durability of concrete structures. This paper systematically studies the performance, applicability, and impact of different types of anti-corrosion coatings on concrete durability, focusing on their resistance to chloride ion penetration, freeze–thaw cycles, carbonation, and sulfate corrosion. The applicability of existing testing methods and standard systems is also evaluated. This study shows that surface-film-forming coatings can create a dense barrier, reducing chloride ion diffusion coefficients by more than 50%, making them suitable for humid and high-chloride environments. Pore-sealing coatings fill capillary pores, improving the concrete’s impermeability and making them ideal for highly corrosive environments. Penetrating hydrophobic coatings form a water-repellent layer, reducing water absorption by over 75%, which is particularly beneficial for coastal and underwater concrete structures. Additionally, composite coating technology is becoming a key approach to addressing multi-environment adaptability challenges. Experimental results have indicated that combining penetrating hydrophobic coatings with surface-film-forming coatings can enhance concrete’s resistance to chloride ion penetration while ensuring weather resistance and wear resistance. However, this study also reveals that there are several challenges in the standardization, engineering application, and long-term performance assessment of coating technology. The lack of globally unified testing standards leads to difficulties in comparing the results obtained from different test methods, affecting the practical application of these coatings in engineering. Moreover, construction quality control and long-term service performance monitoring remain weak points in their use in engineering applications. Some engineering case studies indicate that coating failures are often related to an insufficient coating thickness, improper interface treatment, or lack of maintenance. To further improve the effectiveness and long-term durability of coatings, future research should focus on the following aspects: (1) developing intelligent coating materials with self-healing, high-temperature resistance, and chemical corrosion resistance capabilities; (2) optimizing multilayer composite coating system designs to enhance the synergistic protective capabilities of different coatings; and (3) promoting the creation of global concrete coating testing standards and establishing adaptability testing methods for various environments. This study provides theoretical support for the optimization and standardization of concrete coating technology, contributing to the durability and long-term service safety of infrastructure. Full article

This study utilizes machine learning to quantify CO₂ plume extents by analyzing microseismic data from the Illinois Basin Decatur Project (IBDP). Leveraging a unique dataset of well logs, microseismic records, and CO₂ injection metrics, this work aims to predict the temporal evolution of subsurface CO₂ saturation plumes. The findings illustrate that machine learning can predict plume dynamics, revealing vertical clustering of microseismic events over distinct time periods within certain proximities to the injection well, consistent with an invasion percolation model. The buoyant CO₂ plume partially trapped within sandstone intervals periodically breaches localized barriers or baffles, which act as leaky seals and impede vertical migration until buoyancy overcomes gravity and capillary forces, leading to breakthroughs along vertical zones of weakness. Between different unsupervised clustering techniques, K-Means and DBSCAN were applied and analyzed in detail, where K-means outperformed DBSCAN in this specific study by indicating the combination of the highest Silhouette Score and the lowest Davies–Bouldin Index. The predictive capability of machine learning models in quantifying CO₂ saturation plume extension is significant for real-time monitoring and management of CO₂ sequestration sites. The models exhibit high accuracy, validated against physical models and injection data from the IBDP, reinforcing the viability of CO₂ geological sequestration as a climate change mitigation strategy and enhancing advanced tools for safe management of these operations. Full article

Reducing net carbon emissions is of great significance for sustainability. Carbon capture, utilization, and storage (CCUS) technology is regarded as one of the most effective approaches to reducing net carbon emissions. A prerequisite for the implementation of the CO₂ geological storage project is the assessment of the storage potential of the storage site. In this study, a calculation method of storage potential was proposed to estimate the CO₂ storage potential of the Yanchang shale gas reservoir in the Ordos Basin, China. In this method, the CO₂ sealing capability of the caprock is taken into account, which determines the maximum CO₂ storage pressure of the reservoir. The overall CO₂ storage potential consists of four types of storage states (free-state, adsorption, dissolution, and mineralization). The maximum CO₂ storage pressure of the Yanchang shale gas reservoir is 13.4 MPa via breakthrough pressure experiments, and the corresponding theoretical storage potential is 7.59 × 10¹¹ t. The potential for free-state, adsorption, dissolution, and mineralization sequestration are 8.42 × 10¹⁰ t, 6.88 × 10¹⁰ t, 2.45 × 10⁹ t, and 6.05 × 10¹¹ t, respectively. Due to the difficulty in completing mineralization within the engineering time scale, the mineralization potential should not be taken into account when estimating the available CO₂ storage potential. The available CO₂ potential (including free-state, adsorption, and dissolution) of the Yanchang shale gas reservoir is 1.54 × 10¹¹ t, which is a considerable amount. The Yanchang shale gas formation will be able to accommodate 41.49% of global annual CO₂ emissions (according to the data in 2021) if the available CO₂ storage potential of the Yanchang shale gas reservoir is fully exploited. Full article

In the cement industry, utilization of a sustainable binder that has a lower energy consumption and carbon dioxide (CO₂) emission than Portland cement is becoming increasingly important. Air lime is a binder that hardens by absorbing CO₂ from the atmosphere, and its raw material, hydrated lime, is manufactured at a lower temperature (around 900 °C) than cement (around 1450 °C). In this study, the amount and rate of CO₂ uptake by air lime-based materials are quantitatively evaluated under ambient curing conditions of 20 °C, 60% relative humidity, and 0.04% CO₂ concentration. In addition, the effects of the water-to-binder ratio (w/b) and silica fume addition on the material properties of the air lime mortar, such as strength, weight change, carbonation depth, and pore structure, are investigated. Unlike hydraulic materials, such as Portland cement, the air lime mortar did not set and harden under a sealed curing condition, however, once exposed to dry air, the mortar began to harden by absorbing CO₂. During the first week, most of the internal water evaporated, thus, the mortar weight was greatly reduced. After that, however, both the weight and the compressive strength consistently increased for at least 180 days due to the carbonation reaction. Based on the 91-day properties, replacing 10% of hydrated lime with silica fume improved the compressive and flexural strengths by 27% and 13% respectively, whereas increasing the w/b from 0.4 to 0.6 decreased both strengths by 29% due to the increased volume of the capillary pores. The addition of silica fume and the change in the w/b had no significant impact on the amount of CO₂ uptake, but these two factors were effective in accelerating the CO₂ uptake rate before 28 days. Lastly, the air lime-based material was evaluated to be capable of recovering half of the emitted CO₂ during the manufacture of hydrated lime within 3 months. Full article

As a pump-free and lightweight analytical tool, paper-based microfluidic analytical devices (μPADs) attract more and more interest. If the flow speed of μPAD can be programmed, the analytical sequences could be designed and they will be more popular. This reports presents a novel μPAD, driven by the capillary force of cellulose powder, printed by a desktop three-dimensional (3D) printer, which has some promising features, such as easy fabrication and programmable flow speed. First, a suitable size-scale substrate with open microchannels on its surface is printed. Next, the surface of the substrate is covered with a thin layer of polydimethylsiloxane (PDMS) to seal the micro gap caused by 3D printing. Then, the microchannels are filled with a mixture of cellulose powder and deionized water in an appropriate proportion. After drying in an oven at 60 °C for 30 min, it is ready for use. As the different channel depths can be easily printed, which can be used to achieve the programmable capillary flow speed of cellulose powder in the microchannels. A series of microfluidic analytical experiments, including quantitative analysis of nitrite ion and fabrication of T-sensor were used to demonstrate its capability. As the desktop 3D printer (D3DP) is very cheap and accessible, this device can be rapidly printed at the test field with a low cost and has a promising potential in the point-of-care (POC) system or as a lightweight platform for analytical chemistry. Full article

It is quite common to dispense a topping material like crystalline penetration sealer materials (CPSM) onto the surface of a plastic substance such as concrete to extend its service life span by surface protections from outside breakthrough. The CPSM can penetrate into the existing pores or possible cracks in such a way that it may form crystals to block the potential paths which provide breakthrough for any unknown materials. This study investigated the crystalline mechanism formed in the part of concrete penetrated by the CPSM. We analyzed the chemical composites, in order to identify the mechanism of CPSM and to evaluate the penetrated depth. As shown in the results, SEM observes the acicular-structured crystals filling capillary pores for mortar substrate of the internal microstructure beneath the concrete surface; meanwhile, XRD and FT-IR showed the main hydration products of CPSM to be C-S-H gel and CaCO₃. Besides, MIP also shows CPSM with the ability to clog capillary pores of mortar substrate; thus, it reduces porosity, and appears to benefit in sealing pores or cracks. The depth of CPSM penetration capability indicated by TGA shows 0–10 mm of sealer layer beneath the concrete surface. Full article