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Segmentation of X-ray computed tomography (CT) images of four-phase unsaturated rooted soils is challenging yet a crucial step for conducting the subsequent image-based analysis (IBA) for various properties, for instance, volume fraction of each phase, morphologies of pore and roots, pore fluid distributions and some engineering properties such as hydraulic conductivity. The accuracy and efficiency of phase segmentation have been widely investigated, but the segmentation uncertainty (SU), which is a measure of reproductivity or reliability, on IBA and how the uncertainty propagates at different stages of IBA have rarely been studied for rooted soils. In this study, we developed a machine learning (ML)-based technique, called the percentile-based segmentation method, to perform phase segmentation of CT images and quantify the uncertainty and propagation of phase segmentation at different stages of IBA. Two indicators were used: relative value (RE), which has been used in the literature and SU magnification factor (SU-MF), which is newly proposed in this study. X-ray CT images of soil samples with different particle sizes and cultivated with different plant species were taken by a micro-X-ray CT scanner. The images were then segmented using the proposed ML method. In the presentation, a detailed case study and sensitive analysis (e.g., different number of phases, plant species, sampling resolution, and simulation methods) will be presented. We will show that root volume is susceptible to SU yet has a marginal influence on CT-IBA as its fraction is relatively small compared to other phases. However, the volume of soil grains is less SU-sensitive, which could lead to a significant change in the IBA. Root architectures could substantially influence the SU. Increasing the segmentation percentile improves the reliability, but the accuracy reduces at the same time. Moreover, we will show that the newly proposed indicator, SU-MF, can reasonably reflect the SU propagation behaviour. Therefore, SU could significantly impact the CT-IBA of rooted soils, and SU propagation is phase- and parameter-dependent. The explored quantification and propagation of SU provide novel and practical perspectives for increasing the measurement reliability of the X-ray CT-IBA of rooted soils.

Slope stability is generally analyzed by a two-dimensional (2D) method, ignoring the spatial effect (SE), which no longer meets the evaluation accuracy requirement. This problem is particularly prominent for embankments built on double V-shaped gullies (E-DVSG), which is a typical but unique topography in mountainous areas. Moreover, the technical requirements for engineers will increase sharply if a three-dimensional (3D) slope stability calculation method is adopted. To tackle this issue, pragmatically, a dimension-reduced slope stability analysis method (DR-SSAM) considering the SE of the E-DVSG was proposed and verified by a case study. Specifically, the DR-SSAM obtained the 3D safety factor of the E-DVSG by using the spatial effect curves and the safety factor from the 2D model. The results showed that this method was rational and efficient for engineering applications. In addition, the SE generation mechanism and condition, along with the influences resulting from the major factors, were addressed thoroughly.

Cement has been well documented to positively affect the early-age strength of the cement asphalt emulsion mixtures (termed as CAEM) without compromising workability. However, the long-term performance of the CAEM incorporating multiple cement combinations is not conclusive. This study explored the effect of the combined usage of ordinary portland cement (OPC) and sulfoaluminate cement (SAC) on the long-term performance and microstructural properties of a CAEM system in detail. Three tasks were conducted, including (1) designing six CAEM formulations by introducing different types (OPC and SAC) and contents (2–6 wt%) of cement; (2) evaluating the long-term performance by moisture susceptibility, frost damage, abrasion resistance, and rutting resistance; and (3) characterizing the microstructural properties by scanning electron microscopes and energy-dispersive spectrometers. The experimental results revealed that the relative dynamic elastic modulus of CAEM was increased to 69.7% when admixing 90 wt% OPC and 10 wt% SAC. The mixture incorporating 90 wt% OPC and 10 wt% SAC demonstrated excellent rutting resistance up to ~ 31,000 cycles/mm of dynamic stability. The improved long-term performance actually originated from the reduced voids and produced a dense microstructure. The outcomes could facilitate tailoring CEAM products with better long-term performance.

Unlike conventional approaches of direct addition of carbon-based conductive fillers into cement matrix in developing smart sensing composites, this study proposes a targeted and therefore more efficient approach through nano-surface engineering of the sand. Specifically, a simple method that enables uniform adsorption of graphene oxide onto the surface of the sand particles, followed by simple annealing and microwave treatment to prepare graphene-coated sand (conductive aggregates). Scanning electron microscopy indicates that about 62.2% of the sand surface area is successfully coated by graphene, with an average thickness of approximately 8.8 nm. The mortar incorporating conductive aggregates demonstrates outstanding electrical conductivity (resistivity of 960 Ω·cm) and a high fractional change in resistivity of ∼ 18% under cyclic compressive loading, which outperforms previously reported results obtained by direct addition of graphene or carbon nanotubes at equivalent concentrations. The use of conductive aggregates in mortars also results in other minor benefits such as a slight enhancement in flowability and reduction in water sorptivity. All of these were achieved without substantial reduction in 28-d compressive strength. These findings demonstrate a great potential of aggregate surface nano-engineering for developing smart cement-based composites for practical sensing applications.

Currently, modeling of social impacts in sustainable pavement management (SPM) is still in the infant stage, which generally causes significant social impacts and triggers several social hotspot issues. Therefore, this paper aims to evaluate the social impacts on pavement over its main life-cycle stages. To achieve this goal, the UNEP/SETAC guidelines were employed to develop the social life-cycle assessment (S-LCA) framework for pavement. Stakeholders, subcategories, and part of social indicators were identified from previous studies, and the other part of social indicators were particularly developed based on pavement characteristics. In particular, direct and indirect social indicators were both used, which evaluate social impacts directly and indirectly, respectively. Moreover, site-specific data were extensively collected and verified using cross-checking by multiple data collection approaches and sources, while generic data were adopted as reference values. Subsequently, the existing approaches of assigning scores were applied for direct and indirect social indicators, and the weights were determined using the analytic hierarchy process method. A final score was aggregated to evaluate the social impacts of pavement. In addition, a case study of traditional hot-mix asphalt (HMA) in China was applied and the social hotspots were identified for the local pavement sector. This study involved four pavement life-cycle stages of raw materials and production, construction, use, and maintenance, along with 4 stakeholders, 12 subcategories, and 16 social indicators. In particular, the use stage was addressed due to its significant social impacts during the long service life for pavement. Moreover, the subcategories and social indicators associated with worker category were most integrated, and the consumer was incorporated. In the case study of HMA pavement, the use stage contributed the greatest positive social impacts, while local community was identified as an important stakeholder, followed by worker. In addition, the subcategories of health and safety received the top three scores. However, gender discrimination was a significant social problem in the local pavement sector as indicated by the lowest score of equal opportunities subcategory. The proposed S-LCA framework is effective in evaluating the social impacts of pavement related to affected stakeholders during its main life-cycle stages. This study lays the foundation for the development of S-LCA framework for pavement, and the identified and proposed social indicators not only are used to evaluate the comprehensive social impacts of pavement, but also are suitable for other construction projects.

Nature-based solution using vegetation has been considered as a sustainable and environmentally friendly approach to improve slope performance through root reinforcement and variations of soil matric suction upon transpiration. During plant growth, roots explore soil pore space. How fundamentally the pore structure might evolve with time following root growth dynamics and how this dynamic soil-root interaction may modify the hydraulic properties of unsaturated soils remain unclear. This paper reports the use of advanced technologies including artificial intelligence (AI) to aid the discovery of soil-root-water physical interaction and the characterisation of the hydraulic properties of rooted soils. A newly developed miniature unsaturated triaxial apparatus that enables rooted soil samples to subject to simultaneous in-situ loading and X-ray imaging is introduced. An AI-informed image processing technique is illustrated, aiming to enhance the reliability of phase segmentation of X-ray computer tomography (CT) images of four-phase unsaturated rooted soils for quantifying 3-D pore structure and root phenotype. New discoveries of how roots interact with the pore space, including the dynamic changes in the distribution, orientation and connectivity of soil pore sizes, and how this pore-level information can be used to explain the hydraulic properties are discussed.

This paper presents a preliminary study of the damping performance (DP) and mechanism of crumb rubber modified (CRM) asphalt. The loss factor (LF) temperature spectra of a dynamic shear rheometer was applied to evaluate the damping performance of crumb rubber (CR) and styrene-butadiene-styrene (SBS) compound modified (CSCM) asphalts using with four criteria. The results showed that CSCM asphalts exhibited a good damping performance with a wide effective damping temperature range, low damping temperature susceptibility, and relatively high LF in normal working temperature range of pavement. This finding served as an indirect but novel explanation for the superior noise reduction of CRM asphalt pavement. Then, an initial investigation of the damping mechanism of CSCM asphalts was conducted by analyzing molecular structure, thermal behavior, and morphology. The results showed that the integrity (synergistic effects of each component in the polymer system) strongly influenced the damping performance of CSCM asphalts through the temperature and blending of polymers and additives. The finding would facilitate the application of CRM asphalts-based damping materials, which can assist to develop sustainable solutions to tackle worldwide environmental problems to some extent.

The objective of this study is to investigate the effect of the steel fiber (STF) contents (0, 0.5%, 1% and 2%) on the tensile basic creep behavior of lightweight aggregate concrete (LWAC) during the early-age and the overall 14 d. The results showed that the tensile basic creep and autogenous shrinkage of LWAC were both significantly reduced by adding STF and the reduction was improved with the increase of STF contents. Moreover, early age contributed more than 86% of total tensile creep for all concretes during the overall 14 d. Furthermore, STF has a slight reduction on creep/shrinkage ratio (CSR) during the overall 14 d, regardless of any STF contents. In addition, the mechanical and microstructural properties of concretes were comprehensively investigated to better understand the tensile basic creep behavior and autogenous shrinkage of LWAC with various STF contents.

Modeling life-cycle sustainability assessment (LCSA) for pavement alternatives is still in infant stage. This paper proposes a comprehensive pavement LCSA methodology that integrated life-cycle cost analysis (C-LCA), environmental life-cycle assessment (E-LCA), and social life-cycle assessment (S-LCA). A four-step structure was developed for the proposed methodology, including system definition, modeling, unifying, and interpretation. First, the goal and scope were defined and pavement alternatives were identified during the four main life-cycle phases, including raw materials and production, construction, use, and maintenance. Second, pavement C-LCA, E-LCA, and S-LCA were measured in the modeling process, where the foreground project and background inventory data were collected, and the various impact assessment models were proposed. Third, a multi-criteria decision-making model was applied to unify the three sustainability dimensions, and select the appropriated sustainable pavement alternative. Finally, the results were discussed and highlighted in interpretation step, and a sensitivity analysis on weights was carried out. A case study was applied to illustrate the proposed methodology, including thin hot mix asphalt concrete layer (THMACO), hot mix asphalt with warm mix additive Sasobit (HMAW), and hot mix asphalt with reclaimed asphalt pavement (HMAR) in Southeast of China. The results show that the recycling-based HMAR contributed the best economic and social performance, while HMAW achieved the best environmental performance. A combined AHP-VIKOR model was applied, and HMAR was selected as the optimal alternative. In addition, a sensitivity analysis on weights was conducted using 21 cases.

SBS-modified bitumen (SMB) is susceptible to aging, which seriously influences its service performance and life. In order to strengthen the anti-aging ability of SMB, triethoxyvinylsilane was designed to organically modify layered double hydroxides (LDHs) and was applied to modify SMB. The dispersibility and storage stability of LDHs in SMB were markedly enhanced after triethoxyvinylsilane organic modification, and the compatibility and storage stability of SBS in bitumen were simultaneously enhanced. Compared with SMB, the introduction of LDHs and organic LDHs (OLDHs) could ameliorate the high-temperature properties of SMB, and the thermostability of SBS in bitumen at a high temperature was also distinctly improved, especially OLDHs. After aging, due to the oxidation of molecular bitumen and the degradation of molecular SBS, SMB became hardened and brittle, and the rheological properties were significantly deteriorated, which had serious impacts on the performance of SMB. LDHs can mitigate the detriment of aging to bitumen and SBS, and the deterioration of the rheological properties of SMB is obviously alleviated. As a result of the better dispersibility and storage stability, OLDHs exerted superior reinforcement of the anti-aging ability of SMB.

Magnesium oxychloride (MOC) cement as viable substrate candidate has unique applications in a range of functional and novel sensing applications due to their low thermal conductivity, high toughness, durability and excellent fire resistance. Here, we developed a facile strategy to fabricate metallized patterns on MOC cement composites through laser-induced selective metallization. The laser sensitiser of copper hydroxyl phosphate [Cu2(OH)PO4] was incorporated into MOC cement to prepare MOC cement composites. Then, the metallized copper patterns were obtained on MOC cement composites after 1064 nm pulsed laser activation and electroless copper plating (ECP). The obtained copper layer on MOC cement composites exhibited high electrical conductivity and excellent mechanical adhesion to the substrate. Furthermore, the rough copper patterns exhibited self-cleaning ability after superhydrophobic modification, which could prevent the surface from being contaminated. The metallized copper pattern could rapidly heat up when energised due to the Joule heating effect, and it can be applied for electric heating and automatic deicing in winter. In addition, a UV photodetector was fabricated by designing an interdigital metallized pattern combined with the UV light response characteristics of nano-ZnO, which has potential application on intelligent functional devices.

This paper first presents the evaluation of damping performance of four types of asphalts: base, non- polymer modified, polymer modified, and stress-absorbing modified asphalts using the temperature spectra of the loss factor (LF) based on dynamic shear rheometer. The results showed that the styrene-butadiene-styrene (SBS) and crumb rubber (CR) were the optimal polymers to improve the damping performance of the base asphalt based on four criteria. The damping performance of SBS and CR modified asphalts was further improved by the proper addition of crosslinker and plasticizer, and the SBS/CR compound modified asphalts held good damping performance for a complementary effect. A high damping capacity of stress-absorbing modified asphalts was observed.

Current life-cycle sustainability assessment (LCSA) methodology for pavement alternatives is deterministic, which generally reduces the reliability of the results. This study proposed an uncertainty-based LCSA framework for pavement alternatives to capture the uncertainties associated with economic, environmental, and social pillars during the life cycle. After identifying and characterizing the uncertainties, the probabilistic LCSA results associated with eight impact categories were obtained using Monte Carlo simulation. Subsequently, an improved multi-criteria decision-making approach was presented to unify the random outcomes of the eight impact categories, where the probabilistic integrated sustainability degrees (ISDs) were obtained to represent the sustainability level for the alternatives. Meanwhile, the probability of being best option for each alternative was obtained. A case study was applied to perform the uncertainty analysis of LCSA including hot mix asphalt (HMA) pavement, warm mix asphalt (WMA) pavement, and reclaimed asphalt pavement (RAP). The results showed the economic performance of RAP alternative was significantly less than that of HMA and WMA alternatives at confidence levels of 97% and 99%, respectively. Moreover, there were no statistically significant differences among three alternatives with respect to relevant environmental impact categories. Three pavement alternatives denoted positive social impacts with 95% confidence interval. In addition, the satisfactory ISD was obtained for RAP alternative with 95% confidence interval, while RAP alternative was selected as the best option with a high probability of 91.71%. In addition, it was found that the ISDs were sensitive to the economic and social weights in the case study. This study extends the existing pavement LCSA framework by capturing the multivariate potential uncertainties, and thus represents a valuable, reliable tool for decision makers.

The effect of warm-mix additive (WMA) on styrene-butadiene-styrene (SBS)-based high-viscosity asphalt (HVA) was conducted in this study. First, the physical properties for control HVA and H...

Damping is essential to bearing dynamic loads of construction structures, such as bridges, pavements, and high-speed rails. This paper presents a novel and preliminary understanding of the damping property and mechanism of styrene-butadienestyrene modified (SBS-modified) bitumens. The damping property was evaluated based on the temperature spectra of the loss factor (LF) by a dynamic shear rheometer and the damping mechanism was interpreted from molecular structure, morphology, and thermal analysis, respectively. The results first demonstrated that the SBS-modified bitumens appeared to maintain good damping property with a wide effective damping temperature range, low damping temperature susceptibility, and relatively high LF in normal working temperature range of pavement. In addition, the damping property seemed to be further improved separately by the crosslinker and plasticizer and the synthetic role on improving damping capacity was also observed by the combination of these two additives. Furthermore, the damping property of the SBS-modified bitumens appeared to be considerably influenced by temperature and the integrity of the hybrid via polymers blending and the use of additives. It was noted that the plasticizer promoted the swelling process of SBS polymers, by which improved the dispersion and chain movement ability. Moreover, the crosslinker increased the internal friction by forming denser polymer network. The findings in this paper will facilitate the development and application of the SBS-modified bitumen based damping materials in noise and vibration reducing and controlling to some extent.

In this study, the performance and modification mechanism of EVA (ethylene-vinyl-acetate) modified (EM), EVA/SBS (Styrene-Butadiene-Styrene) modified (ESM), and EVA/SBS/sulfur modified (ESSM) bitumens were evaluated. The physical, rheological, morphological, and structural properties were determined before and after aging, and compared with those of base bitumen. These properties were evaluation using conventional physical methods, Fourier transform infrared spectrometer, optical microscopy, dynamic shear rheometer, and bending beam rheometer, respectively. The results showed that sulfur was useful in bitumen, EVA, and SBS modification by forming a vulcanized crosslinking polymer network. The vulcanization improved most of the physical properties of ESM bitumen, especially high- and low-temperature performance, and toughness and tenacity (previously not evaluated in the literature). Meanwhile, vulcanization improved the compatibility between polymers and bitumen and increased the aging resistance of ESM bitumen. Vulcanization reactions took place without new functional groups being presented in the infrared spectrum. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 133, 44850.