Low-Carbon and Green Materials in Construction: Latest Advances and Prospects

1. Introduction

In recent years, with the acceleration of urbanization and the continuous expansion of construction at all scales, the safety, durability, and sustainability of building structures have come to face multiple challenges. The degradation of existing masonry structures due to material aging, natural disasters, and environmental erosion has become increasingly prominent; meanwhile, the high carbon emissions and resource consumption of concrete structures in new construction projects have created a critical bottleneck that restricts green development. Additionally, the surge in construction waste, the accumulation of marine waste, and the limitations of traditional building materials all necessitate technological innovation that will drive the transition of the construction industry towards lower carbon emissions, intelligent construction, and resource recycling.

To address these challenges, this Special Issue focuses on cutting-edge research directions such as structural reinforcement, novel material development, intelligent detection technologies, and resource recycling, compiling innovative research findings from interdisciplinary fields. In the area of structural reinforcement, researchers have significantly enhanced the bearing capacity and durability of structures by optimizing the bond behavior between fiber-reinforced polymer (FRP) and masonry interfaces [1], developing prefabricated recycled aggregate constructional columns with excellent seismic performance [2], and exploring the synergistic reinforcement mechanism of hybrid fiber-reinforced concrete columns [3]. In the field of intelligent detection and evaluation, an automated framework for detecting damage to building façades based on multimodal data fusion [4] has broken through the efficiency bottleneck of traditional manual inspections, providing a high-precision solution for building operation and maintenance.

In terms of new material development, scholars have effectively reduced resource consumption and carbon emissions by improving high-sulfated aluminate cement through the synergistic activation of industrial solid waste [5], producing unburned bricks from engineering waste soil [6,7], and developing sea sand–seawater-based dry-pressed concrete paving blocks [8]. Research on the durability of steel and concrete, including the simulation of steel damage under high temperatures using peridynamics theory [9] and the study of the evolution of concrete performance in sulfuric acid corrosion environments [10], has provided theoretical support for improved engineering safety. Furthermore, the proposal of shield slag recycling technology [11] and the performance prediction model for marine waste-based cement composites [12] have further expanded the high-value application pathways of construction waste.

Through a combination of theoretical exploration, experimental validation, and engineering practice, this Special Issue systematically showcases the latest advancements in the construction field, encompassing structural performance enhancement, low-carbon material innovation, and intelligent operation and maintenance technologies. It provides important scientific evidence and technical references for promoting the green transformation and sustainable development of the construction industry. The core contributions of each study and their implications for engineering practice are analyzed below.

2. Overview of This Special Issue

Zhen Lei et al. [1] addressed the challenges to the safety of masonry structures posed by building aging and natural disasters, and embarked on a study of the behavior of the interfacial bonds of CFRP-reinforced clay brick masonry walls in order to fill the gap in the understanding of impacts on mortar joints. They systematically investigated the bond behavior of the interface between CFRP and clay brick masonry through single-shear tests. Single-brick specimens were used to study the bond behavior of pure brick substrates, while masonry prism specimens were employed to simulate actual masonry structures containing mortar joints. The study was conducted by varying parameters such as bond length, bond width, mortar joint condition, and end anchorage conditions. The results indicate that increasing the bond width of CFRP can significantly enhance the bond strength. This provides significant guidance for engineers in terms of optimizing CFRP reinforcement designs in practical engineering. By rationally selecting the bond width and length, the reinforcement effect can be improved without significantly increasing costs.

Linren Zhou et al. [2] proposed and investigated a novel prefabricated constructional column (PCC) made of recycled lump concrete, aiming to evaluate its seismic performance. By comparing its performance with that of traditional cast-in-place constructional columns (CCCs) in restraining walls, the advantages of the PCC in terms of enhancing construction efficiency, reducing costs, and achieving environmental benefits were verified. The authors designed and developed a PCC using recycled lump concrete as the primary material. Through segmented prefabrication, reinforcement bar overlapping, grouting connection technology, and a convex–concave interlocking joint design, rapid assembly was achieved, with a prefabrication rate exceeding 85%. To verify the mechanical properties and connection reliability of the PCC, the authors fabricated PCC test segments and conducted loading tests. Subsequently, experimental models of walls restrained by CCCs and PCCs were established, and low cyclic reversed loading tests were carried out to evaluate their seismic performance. The study innovatively combines prefabrication technology with recycled concrete, providing the construction industry with an efficient, economical, and environmentally friendly solution. It holds significant value for enhancing structural seismic performance and promoting resource recycling, with the potential to become an integral part of future low-carbon building systems.

In traditional reinforced concrete structures, the durability failure of rectangular columns is often caused by the corrosion-induced cracking of the corner steel rebars. Despite the excellent corrosion resistance of glass fiber-reinforced polymer (GFRP) rebars, their linear elastic constitutive relationship results in sudden brittle failure of pure GFRP-reinforced concrete columns. Wenjun Qu et al. proposed a hybrid reinforced concrete column with GFRP rebars replacing ordinary steel rebars in the corner regions of rectangular columns to overcome the brittleness of GFRP rebars and the susceptibility of steel rebars to corrosion, thereby enhancing the durability and reliability of the structure. To this end, Lei Pang et al. [3] designed 10 groups of hybrid reinforced (steel and GFRP)-concrete short column specimens and conducted eccentric compression tests by varying parameters such as eccentricity, concrete strength, reinforcement ratio, and axial stiffness ratio. This systematic study investigated the crack development, strain distribution, failure modes, and bearing capacity characteristics of this novel hybrid reinforced-concrete short column. This research improves the durability and bearing capacity of structures through rational selection and design of hybrid reinforcement, and has important implications for enriching the theory and practice of concrete structure design.

Pujin Wang et al. [4] addressed the issue of how underutilized the complementary advantages of multimodal image data are in building façade damage detection. They then proposed an end-to-end automated framework for detecting damage to the exterior walls of buildings. By innovatively integrating multimodal image registration, infrared–visible image feature fusion (IVIF), and instance segmentation techniques, their framework achieves efficient and precise façade health assessments. For the purposes of their study, they constructed a dataset comprising 1761 pairs of high-resolution infrared–visible images, covering four typical damage types—moisture/leakage, efflorescence, cracking/scratches, and material delamination/gaps. A feature point extraction algorithm based on main orientation assignment was then proposed to achieve high-precision multimodal image registration, yielding an RMSE of 14.35 that outperforms methods such as RIFT and MS-HLMO. A dual-discriminator-based generative adversarial network (GAN-based IVIF) was designed to preserve the high-contrast damage features in the infrared images and the texture details of the visible images through adversarial training. An enhanced instance segmentation model (adopting the CSPRepPAFPN architecture) was employed, achieving a mean average precision (mAP) of 85.4% across the four damage detection categories, with a processing time of only 20 s per image pair. This study offers efficient and reliable technological support for the field of building health monitoring, advancing the practical application of intelligent detection technologies and holding significant practical value in terms of enhancing building maintenance efficiency and mitigating safety risks.

Guangzheng Qi et al. [5] addressed the limited engineering applications of supersulfated cement (SSC), which stem from its low early strength and slow hardening rate, by proposing a novel modification strategy based on the synergistic activation of industrial solid wastes. After introducing calcium aluminate (CA) and carbide slag (CS) as composite alkaline activators, combined with the sulfate activation effect of anhydrite, they systematically investigated the hydration kinetics and mechanical property evolution of the CA-CS-SSC system. For the purposes of their study, they designed four groups of CA-CS-SSC systems with varying ratios and employed various characterization techniques to reveal the synergistic mechanism between CA and CS. The results indicate that a composite system with 1% CA and 4% CS exhibits the optimal performance characteristics. The addition of appropriate amounts of CA and CS optimized the pore structure of the hardened cement paste, reduced porosity, and enhanced density. By optimizing the formulation and preparation process of the SSC, the research team resolved the issue of slow early strength development. These performance improvements to SSC contributes it being accepted as a low-carbon, energy-efficient, and environmentally friendly cementitious material that can help promote the low-carbon development of the cement industry.

Xingzhong Nong et al. [6] dedicated themselves to exploring effective methods for the treatment of construction debris in response to the environmental and social challenges posed by their disposal, aiming to achieve efficient resource utilization. They successfully produced unburned bricks that meet engineering requirements by using residue soil from construction waste as a raw material, adding an appropriate amount of cementitious materials, and optimizing the preparation process. Their research primarily focused on the factors influencing the compressive strength of unburned bricks, including the amount of cementitious materials, the treatment process for the residue soil, the molding method, and the moisture content of the mixed materials. The research results indicate that by adding 5–20% of ordinary cement, unburned bricks with a compressive strength of 5–20 MPa can be produced, and the utilization rate of the residue soil reaches as high as 80–95%. It is noteworthy that the residue soil does not need to be completely dried; instead, simply screening the particles to within 5 mm can simplify the preparation process and reduce production costs. The group’s experiments found that adopting a static press molding method with a pressure of 10 MPa and controlling the moisture content of the mixed materials to around 13% can make the brick body denser and stronger. This research not only provides an efficient and low-consumption technical solution to the challenge of safely disposing of construction residue soil, but also injects innovative impetus into engineering practice through the dual optimization of environmental and economic benefits, exhibiting significant practical significance for the promotion of the industrialization of green building materials and achieving a low-carbon transformation in the construction industry.

Xingzhong Nong et al. [7] conducted a study, investigation, and discussion on the effects of mud type and content on the compressive strength of non-fired bricks made from engineering waste soil. In their study, ordinary Portland cement was used as the cementitious material to prepare test specimens of non-fired bricks made from engineering waste soil with different mud types and varying mud contents. The study systematically explored the influence of mud type and content on the compressive strength of the non-fired bricks. Their experimental results indicate that the effect of different mud types on the compressive strength of the non-fired bricks was not significant, with the compressive strength differences falling within 10% under both the 14-day and 28-day curing periods. In contrast, the impact of mud content on the compressive strength of the non-fired bricks was more pronounced. This research provides a solid theoretical basis and practical guidance for the resourceful utilization of engineering waste soil, holds significant economic and environmental value, and contributes to the development of a resource-efficient and environmentally friendly construction industry.

Pengcheng Guo et al. [8] innovatively proposed using untreated sea sand and seawater directly as substitutes for traditional materials to produce compression-compacted dry concrete paver blocks, addressing the shortage of natural river sand and fresh water. Through the in-depth analysis of the strength data of specimens made using different mix proportions, forming pressures, sea sand replacement ratios, and seawater replacement ratios, the comprehensive effects of various factors on the mechanical properties of the paver blocks were systematically explored. The study found that the water-to-cement ratio, the molding pressure, and the substitution rates of sea sand and seawater all influence the strength of the paving blocks. This research proposal is not only environmentally friendly and low-carbon, but it also effectively reduces the use of natural river sand and fresh water while avoiding the consumption of fresh water and energy during the desalination process of sea sand. It provides a solid theoretical and practical basis for the large-scale application of sea sand and sea water in non-structural concrete products.

Jinhai Zhao et al. [9] applied peridynamics (PD) theory to an investigationg of the damage and crack propagation mechanisms of steel materials under high temperatures and the influence of bolt holes, effectively overcoming the limitations of traditional methods. They derived temperature-dependent peridynamic parameters, such as the elastic modulus and thermal expansion coefficient, and developed a peridynamic program using the Fortran programming language. A two-dimensional physical model, loading zone model, and crack model for Q345 steel were constructed. Through the use of these models, they simulated the crack propagation paths and displacement responses of specimens with central double cracks at different temperatures. They also established specimen models with varying numbers and positions of bolt holes to conduct an in-depth analysis of the deflection effects of bolt holes on crack propagation paths. They experimentally validated the accuracy of the peridynamics model and demonstrated its advantages in handling crack tip singularities and mesh dependencies. By innovatively combining PD theory with high-temperature engineering problems, this paper provides important theoretical tools and engineering references for the design of fire-resistant steel structures, for bolt connection optimization, and for structural health monitoring, ultimately demonstrating significant practical value and potential.

Jie Xiao et al. [10] conducted accelerated corrosion experiments on concrete specimens of three different strength grades exposed to sulfuric acid environments. Innovatively employing three-dimensional laser scanning technology, they acquired precise 3D coordinate data on the concrete surfaces. The fractal dimension of the surfaces before and after corrosion was scientifically calculated using the cube covering method, and the results were analyzed in conjunction with mass loss rates. Their findings indicate that, when evaluated based on three dimensions—surface deterioration, mass degradation, and roughness evolution (quantified by fractal dimension)—the sulfuric acid corrosion severity of concrete increases with higher strength grades, following a descending order of susceptibility: C80 > C50 > C30. This paper innovatively adopts the quantitative indicator of three-dimensional fractal dimension to characterize roughness changes to the surface of concrete under sulfuric acid corrosion, providing a new perspective and method for the precise assessment of the degree of corrosion affecting concrete. This effectively makes up for the shortcomings of traditional evaluation methods in describing concrete surface roughness and this paper enriches the existing research on the corrosion characteristics of concrete in sulfuric acid environments, provides new theoretical insights into the durability of concrete, and contributes to the improvement of the theoretical system for evaluating concrete corrosion.

Gang Chen et al. [11] innovatively proposed a comprehensive recycling technology for shield slag specific to sandy strata, encompassing multiple systems including mud–water separation, sand washing, pressure filtration, and light-wave brick making. In the study, they not only elaborated on the parameters of equipment for each system but also precisely described the operational processes, comprehensively outlining the entire process from shield excavation discharge to the final production of resource-based products. Through technological innovation and empirical validation, this study provides a systemic solution for the treatment of shield slag resources in a way that excels in environmental, economic, and social performance, offering crucial technical support to and practical reference for sustainable urban development, thereby possessing profound practical significance.

Seung-Jun Kwon et al. [12] explored the performance evolution of the binary composites of oyster shell powder (OSP) for replacing cement at various substitution levels. They systematically analyzed the changes in the hydration heat, compressive strength, ultrasonic pulse velocity (UPV), and surface electrical resistivity of concrete over time, and revealed the inherent relationships between these properties and hydration heat. Based on the CO₂ emission data of mortar components, they accurately calculated the CO₂ emissions of mortar with different OSP substitution levels. In their study, the team innovatively proposed a three-parameter equation (TPE) model based on the hydration process. Their paper systematically evaluates the performance and sustainability of oyster shell powder–cement composites through a combination of experimental testing and modeling, providing an important tool for the development of green building materials, low-carbon structural design, and engineering applications.

Jiajing Xu et al. [13] systematically reviewed and contrasted the calculation methods used to evaluate the buckling capacity of cross-bracing in steel transmission towers as stipulated in various design codes. These methods were comprehensively compared with experimental results from the literature and the team’s study revealed that the existing design codes generally fail to adequately consider the significant impacts of torsional stiffness and joint connection type on the bearing capacity of cross-bracing. To address these limitations, the study innovatively introduces a modified effective length coefficient (K), which comprehensively considers the combined effects of torsional stiffness and joint connection type on the bearing capacity. This improvement addresses the lack of these factors in existing design codes. A piecewise formula was proposed to adapt to different slenderness ratio ranges, thereby enhancing the accuracy of the calculated results. By reasonably taking into account the effects of joint connection and torsional stiffness, this study enables the optimization of the size and arrangement of cross-bracing, reducing steel consumption and aligning with the development trends of green building design, energy conservation and emission reduction.

Liancheng Li et al. [14] aimed to investigate the influence of loading rate and fiber bar type on the mechanical properties of concrete one-way plates using drop-weight impact tests. By simulating impact loads at different heights (0.25 m, 0.5 m, and 1 m), the dynamic performance of six concrete one-way plates equipped with either glass or basalt fiber bars was tested. The study found that as the loading rate increased, the damage level of the fiber-reinforced concrete one-way plates gradually increased, with corresponding increases in peak deflection and residual displacement at the mid-span. Glass fiber-reinforced concrete one-way plates exhibited slightly superior impact deformation capabilities and better impact toughness compared to their basalt equivalents. The findings of this study contribute to promoting the use of fiber-reinforced composites as alternatives to traditional steel in practical engineering, effectively reducing the corrosion risk of concrete structures and extending their service life, as well as aligning with the principles of modern green engineering.

Baogui Zhou et al. [15] conducted a systematic simulation study on the reinforcement of high backfill slopes with anti-slide piles using MIDAS.GTS.NX 2019 geotechnical finite element software. Building on this foundation, they further delved into the influence mechanisms of anti-slide pile parameters on the stability of high fill slopes. The research findings reveal that the displacement characteristics of high backfill slopes are primarily manifested as vertical settlement. The study also found that the length, diameter, and spacing of the anti-slide piles significantly affect the horizontal displacement of the slope. The location of the anti-slide piles is also crucial for the reinforcement effect, with the optimal reinforcement outcome being achieved by placing the anti-slide piles on the first level of the slope platform. The research results presented in this paper not only contribute to enhancing engineering safety and reducing construction costs but also hold significant importance in terms of promoting the development of slope engineering technology.

Jie Su et al. [16] innovatively proposed alkali-activated geopolymer ultra-high-performance concrete (UHPGC) as a low-carbon alternative to address the high carbon emissions of traditional Portland cement-based ultra-high-performance concrete (UHPC). In order to examine the flexural performance of the UHPGC beams, the research team meticulously prepared five UHPGC beams and conducted four-point bending tests to systematically investigate the significant impact of steel fiber content and longitudinal reinforcement ratio on their flexural performance, encompassing such characteristics as bearing capacity, stiffness, crack development, and ductility. It is noteworthy that previous studies are predominantly focused on UHPC beams, with relatively few studies investigating UHPGC beams. This research not only fills this gap in the study of flexural performance of UHPGC beams but also provides a solid scientific basis and valuable reference data for the widespread application of this novel sustainable material in structural engineering, significantly contributing to the development and adoption of low-carbon building materials.

Jingxian Liu et al. [17] proposed conducting a systematic and in-depth investigation into the carbon dioxide (CO₂) sequestration capacity of a fly ash (FA) and ground granulated blast-furnace slag (GGBS) composite cement system in response to the issue of the high carbon emissions of cement production. They comprehensively evaluating the impact of this system on the carbon emissions of concrete products. During the experiments, the researchers employed the phenolphthalein method and thermogravimetric analysis (TGA) to precisely assess the carbonation depth and carbon content; they utilized nitrogen adsorption (BET) to conduct detailed analyses of the pore structure; and they accurately calculated the embodied carbon emissions of concrete products through a life cycle assessment (LCA). These methods enabled the research team to systematically compare the performance disparities of different composite cements during the carbonation process. This research, through the deployed multi-dimensional systematic analysis, clearly uncovered the complex influence material composition exerts on the carbonation and carbon emissions of cement systems, providing the crucial theoretical basis for the optimal design of low-carbon concrete and laying a solid theoretical foundation for the widespread promotion of low-carbon concrete in construction. This study is expected to drive the construction industry towards greener and more sustainable development.

3. Conclusions

This Special Issue brings together 17 papers on the latest progress of and prospects for the enhancement of structural building performance, low-carbon material innovation, and intelligent operation and maintenance technologies. These articles systematically showcase cutting-edge achievements in the construction field by addressing challenges related to safety, durability, and sustainability from multiple dimensions, including structural reinforcement, novel material development, intelligent detection technologies, and resource recycling. The research contained herein covers key directions such as the interfacial optimization of fiber-reinforced polymers (FRPs), the seismic performance of prefabricated recycled aggregate construction columns, an intelligent detection framework based on multimodal data fusion, the simulation of steel damage under high temperatures, the preparation of unburned bricks from engineering waste soil, and the utilization of marine waste as a resource. These studies provide theoretical support and technical solutions addressing issues such as aging building structures, high carbon emissions, and resource waste.

However, the number of papers included in this Special Issue is limited, and the scope of the research contained therein retains certain limitations. Therefore, future Special Issues should place a greater emphasis on emerging fields such as novel structural systems under carbon neutrality goals, bio-based/self-healing materials, digital twin technology-enabled structural health monitoring, and extreme climate-adaptive design. Additionally, as the global pursuit of carbon neutrality intensifies, continuous breakthroughs will be needed in terms of the low-carbon emissions and renewability of building materials, as well as in terms of energy-saving and emission reduction technologies during construction processes. Furthermore, interdisciplinary cross-research (e.g., the material–information–energy synergy) and the construction of multi-dimensional assessment models integrating policy, economy, and technology will provide more comprehensive solutions for the green transformation of the construction industry. It is anticipated that through continuous technological innovation and academic exchanges, the construction field will be propelled towards a safer, lower carbon, and smarter future.