Construction and Building Materials最新文献

Moisture-induced degradation is an inherent phenomenon at the interface between rubber-modified asphalt and aggregate, moisture ingress through diffusion impairs the integrity of this interface. This study employed molecular simulation to assess the performance of the rubber-modified asphalt and aggregate interface, considering multiple influencing factors such as temperature and loading. Infrared spectroscopy served to validate the alterations in functional groups after moisture exposure. Quantitative metrics, including mean square displacement, interfacial adhesion energy, adsorption energy, radius of gyration, solubility parameter, and molecular orientation, were computed to pinpoint the moisture-induced degradation zones. The findings demonstrated that the maximum moisture diffusion rate subject to various influencing parameters occurred at 298 K and 3 atm, as well as 333 K and 3 atm. Temperature exerted a more profound influence on the rubber-modified asphalt-aggregate interface compared to loading. The strength of hydrogen bonding between moisture and rubber molecules surpassed Van der Waals forces and induction force. Infrared spectroscopy showed that the diffused moisture persisted within the interface.

Rapid global urbanization is driving governments and builders to seek paradigm-shifting technologies to speed the construction of housing and infrastructure at a low economic and carbon cost. Here, we present a novel method for fabricating materially efficient, shape-optimized, code-compliant, reinforced concrete structures cast in directly recyclable 3D printed earth formwork, hereby referred to as EarthWorks. This research demonstrates the potential of zero waste, circular formwork that can be manufactured with construction waste soils directly on site. Methods are described for formwork design and toolpathing that accounts for hydrostatic pressure, conventional reinforcement, high accuracy connections, and the fabrication of complex, 3D-shaped geometry with continuous extrusion. In addition, the building design and performance potential of the EarthWorks method are assessed and compared to existing additive formwork technologies from a carbon perspective. Case studies are fabricated demonstrating cast-in-place, tilt-up, and on-site prefab methods to produce bespoke columns, beams, and frames designed to California building code.

This research studies the durability of self-compacting concrete (SCC) with fly ash (FA), coal gangue powder (CGP), cement kiln dust (CKD), and recycled concrete powder (RCP) by absolute volume method. The fresh properties of self-compacting concrete (SCC) mixtures were assessed by slump flow, T50 cm slump flow, and V-Funnel flow time. The strength and durability properties were evaluated using a compressive strength test, Freeze-thaw resistance, chloride ion penetration, and carbonation resistance tests. Furthermore, the pore structure of concrete after a 90-day curing period was analyzed using Mercury Intrusion Porosimetry (MIP), which provided valuable information on the distribution and properties of pores inside the material. The results revealed that SCC with FA and CKD performed best with a slump flow of 700 mm. Specimens with FA and RCP have greater compressive strength after 90 days of curing, making them appropriate for high-strength applications. In terms of freeze-thaw resistance, SCC with CGP exhibits the lowest mass loss rate, indicating the best resistance, followed by FA and CKD, with RCP showing the least resistance. FA and CKD have excellent enhancement effects for SCC resistance to chloride ions. Specimens with RCP have the lowest carbonation depth and the best carbonation resistance. The findings suggest that the concrete specimens with fly ash (FA) have the highest total pore area and porosity, with a wide range of pore sizes and a prominent peak in the capillary pore size range, indicating a highly porous structure. This study provides practical advice on how to use SCC in construction and improve material selection and optimization.

In the modern era, the importance of prioritizing traffic safety has become increasingly evident, requiring dedicated focus. An effective strategy for improving traffic safety involves optimizing road roughness to minimize road bumps and mitigate the risk of accidents. Currently, artificial intelligence algorithms are widely recognized for their capacity to accurately forecast pavement roughness in intricate environments. The current state of research on road roughness prediction using artificial intelligence approaches is found to be deficient in providing a comprehensive review. This paper aims to provide a comprehensive analysis of the patterns in predicting pavement roughness using artificial intelligence algorithms through a systematic review. This article provides an overview of the development process of IRI prediction and introduces commonly used artificial intelligence methods in the road field. These methods are primarily categorized into machine learning and deep learning. The article also presents a comprehensive overview of the similarities and differences among various works in this domain. Regarding the issue of data sources, it is divided into LTPP database and other databases, summarizing the data sources and volume used in the literature, as well as independent variables including road age, material property, road performance, climate parameters, etc. The challenges and future perspective in predicting road International Roughness Index (IRI) for the future are proposed, taking into consideration the complexity of data collection and limitations on the development of artificial intelligence networks.

This paper presents the finite element analysis (FEA) of a full-scale RC wall-beam-slab joint under reversed cyclic loading. Five different approaches in ABAQUS are introduced to simulate the bond-slip effect between reinforcement and concrete. The concrete damaged plasticity (CDP) model and the combined hardening constitutive model are illustrated and adopted for concrete and reinforcement, respectively. By comparing the overall mechanical behavior of the wall-beam-slab joint predicted by FEA models to that of the test results, the predictive capability of FEA models with different bond-slip simulation methods are studied. In general, the analysis results indicate that the numerical results without the bond-slip effect present a gross overestimation of the overall mechanical behavior, while the numerical results with the bond-slip effect are in good agreement with the test results. Wherein, the FEA models with the bond-slip effect simulated by spring elements or implemented by user-defined subroutine predict more consistent results with the test results. Moreover, the disadvantages of each method utilized to simulate the bond-slip effect have also been described. A comprehensive study on material parameters of concrete is accomplished to obtain the influence of parameters such as the dilation angle(ψ), the ratio of the second stress invariant on the tensile meridian to that on the compressive meridian(K_c), and the viscosity parameters(υ).

This study centers on investigating the effects of multi-ion electrical coupling on sulfate profiles in the convection zone of hydraulic concrete under drying-wetting cycles. Considering the moisture ingress triggered by capillary negative pressure and electrical potential gradients generated due to the varying speeds of the charged solutes, a coupled numerical model framework for moisture and multi-component ions transport is established. The influence of drying and rewetting conditioning regimes, electrochemical coupling between multi-species ions, sulfate adsorption-binding mechanism, fly ash replacement and porosity of concrete on moisture and multi-ion transport behavior is numerically analyzed. Our findings reveal that more than 60 % of the sulfate ions that penetrate the concrete matrix engage in chemical reactions. After 30 cycles, the sulfate ion content differs by approximately 21 % depending on the presence of the electrical coupling effect. Moreover, the electrostatic potential in the pore solution fluctuates sharply in the ion-rich area near the concrete surface, interacting with ion distribution in the convection zone. The knowledge gleaned from this investigation offers a robust framework for the design of concrete structures that need to withstand challenging aqueous environmental conditions marked by multi-component ions and cyclic drying-wetting processes.

The bonding quality of the mixture is critical to the longevity and durability of the asphalt pavement. This paper aims to investigate the influence patterns and intrinsic relationships of various factors including binder, aggregate, moisture, and anti-stripping agents on asphalt-aggregate bonding performance and mixture failure characteristics. Specifically, the influence of various factors on asphalt-aggregate bonding strength was investigated through binder bonding strength (BBS) tests. Next, the disk-shaped compact tension (DCT) and indirect tensile (IDT) tests were used to investigate the influence of different factors on the bonding failure characteristics of mixtures from the perspectives of fracture failure and water damage, respectively, and finally the correlation between the asphalt-aggregate bonding and the mixture failure characteristics was explored. The BBS test results show that crumb rubber significantly deteriorates the bond strength while SBS incorporation shows an insignificant effect on bond strength, and aggregates containing more alkaline components favor bond strength enhancement. The DCT and IDT test results reveal that SBS enhances the fracture and water damage resistance of the mixture, while crumb rubber is detrimental to it. Water causes deterioration of asphalt-aggregate adhesion and reduces the fracture resistance of the mixture. Mixtures containing anti-stripping agents and alkaline aggregates exhibit enhanced resistance to fracture failure and water damage. The fracture energy ratio is preliminarily validated as a new evaluation index for water damage resistance of asphalt mixtures. The correlation analysis shows that the pull-off tensile strength (POTS) correlates well with fracture resistance under consistent asphalt conditions, and the POTS ratio (R_p) could effectively reflect the moisture damage resistance of the mixture. This study provides valuable insights into selecting the optimal material combination for superior bonding performance in engineering practice and enhancing pavement durability.

This paper presents a comprehensive study to establish the threshold limit of CT_Index for the Marshall mixes. The study also aims to assess the impact of different design factors on the cracking resistance of bituminous mixtures using the Indirect Tensile Asphalt Cracking Test (IDEAL-CT) test. This study considers 2 different aggregate sources, 2 different gradations, 5 different types of Design Aggregate Gradation (DAG), 3 binder types, and 5 levels of compactive effort. The test results show that higher cracking resistance can be achieved using a smaller nominal maximum size of the aggregate (NMAS), finer gradation, modified binder, and decreased compactive effort with aggregates having low abrasion and absorptive characteristics. This study also comprehends the influence of volumetric parameters of the bituminous mixes on fracture resistance. It was found that at a particular Optimum Binder Content (OBC), higher bulk specific gravity of the compacted specimen (G_mb) and voids filled with asphalt (VFA) result in reduced CT_Index, specifying poor cracking performance. While higher air voids (AV) and voids in mineral aggregate (VMA) lead to increased CT_Index, indicating better-cracking resistance. Statistical analysis tools were used to evaluate the significance of the influential factors that are affecting the cracking potential of the mix. Different Machine learning models were also developed to predict CT_Index based on the design factors considered in the study. The random forest (RFR) model showed strong accuracy, reflected by low Mean Absolute Error (MAE=3.16), Mean Absolute Percentage Error (MAPE=9.57), Root Mean Square Error (RMSE=4.23), and a high coefficient of determination (R²=0.95) value, notifying a precise fit and reliable predictions. Additionally, a GUI has been also developed to enhance the practical usability of the model for wider usage. Further, the present study proposes the threshold value of CT_Index for the selection of crack-resistant bituminous mixtures. Moreover, the study investigated the correlation between laboratory and field compaction methods and validated the initial threshold specification of CT_Index for the Marshall mixes. Despite of the variations in different compaction methodologies and specimen thickness, a strong positive correlation (R² > 0.76) between laboratory and field cores of BC-1 and DBM-2 indicates that the performance criteria are adequate and justified.

Stone Mastic Asphalt (SMA) is a composite mixture made up of high-quality crushed stone, fine aggregates, an asphalt binder, and a significant percentage of mineral filler in contrast to conventional mixtures. Renowned for its durability and rolling resistance, it is predominantly employed as a surface “wearing” course on main roads subjected to heavy traffic, but it can also be used as a binder course under specific project requirements. In this study, we investigated the effect of hydrated lime as a partial replacement of limestone filler at various concentrations on the mechanical and cracking resistance characteristics of 10-mm SMA mixtures. The semi-circular bending (SCB) test, which is pivotal for understanding the cracking mechanism was used to assess the mixtures performance-related response to this distress type. The mixture cores were produced with granite aggregates, limestone filler as natural filler, hydrated lime as natural filler replacement, and a 30/45 penetration asphalt type. Mixtures containing 1.1 %, 2.2 %, and 3.4 % of hydrated lime by weight of aggregates were evaluated, in addition to a control mixture without hydrated lime. The factors considered for comparing the mixtures included: load and deformation curves, stiffness, fracture toughness, fracture energy, and flexibility index of the mixtures. The experimental program also comprised a set of various test temperatures (0°C, 10°C, and 20°C) to better understand the cracking mechanism. Experimental results indicated a significant performance-dependency on the HL concentration and the test temperature. Precisely, it was found that the mixture with the highest hydrated lime content (3.4 %) exhibited the best cracking performance at 0°C and 20°C, making it a suitable filler replacement concentration. However, at 10°C, the mixture containing 2.2 % hydrated lime showed the most consistent performance overall, suggesting and important improvement in asphalt mixtures’ cracking resistance. Overall, these findings obtained from the SCB test approach substantiate the potential benefit of hydrated lime filler replacement in optimizing the cracking performance and durability of SMA mixtures under varying temperature conditions and loading regimes.

With its high strength and excellent dimensional stability, high-performance wood scrimber (HPWS) holds significant promise for applications in load-bearing structures within buildings. However, understanding its behavior concerning size effects, particularly in terms of strength variation with stressed volume dimensions, is essential for establishing design parameters. Despite this importance, research on this aspect remains scarce. To address this gap, this study conducted tension tests on 304 specimens divided into 10 groups, covering a wide range of sizes, with the largest specimen’s volume 162 times that of the smallest. Utilizing the weakest link theory, the study investigated the size effect on tensile strength parallel to grain. Size effect factors were estimated using the shape parameter and slope methods, with discussions on differences related to volume, length, and cross-sectional area factors. It was found that the size effect related to the length and cross-sectional area were 0.0804 and 0.0671, respectively. This difference was due to the load-sharing ability within the cross-section, as the HPWS in tension resembles a net-like structure more than a chain-like structure. The specimens with the smallest cross-section didn’t exhibit the greatest strength. This was because the effects of sawing are particularly severe for very small specimens. This issue requires careful consideration when developing calculation methods. Finally, a calculation method for the tensile strength reduction coefficient, considering size effects, was proposed and demonstrated to align well with experimental findings. This comprehensive analysis serves to advance the structural utilization of HPWS as an innovative building material.