X-ray computed tomography is a well-known technique to measure porosity in materials such as concrete, though this usually involves time consuming scans and complex analysis procedures. Many of these ...involve custom software or programming procedures. In this paper, a simplified procedure is presented and demonstrated using results obtained from basic procedures with commercial software packages, with minimal image processing. The same sample was subjected to scans ranging from 100 to 5 μm resolutions, demonstrating the multiscale ability of commercial CT scanners. Scans done at typical high-quality conditions (1 h duration) in comparison to very fast scans (5 min) are also presented and it is demonstrated that useful information is still obtained from such lower quality faster scans. This demonstrates the concept that X-ray CT is simple and cost effective for research and industrial applications, not requiring expert 3D image analysis experience, for obtaining useful porosity information within the range of pore sizes resolvable by the technique.
Agricultural informatization and agricultural green development are important components of modern agricultural development, and coordination between the two is an important foundation for achieving ...sustainable agricultural development. This paper uses data from the 13 major grain producing areas in China from 2009 to 2018 to analyze the coordination of the Internet development level and the agricultural ecological-efficiency, and it further investigates the degree of coupling and coordination between the two. The results of theis study are as follows.(1) The Internet development level of China’s 13 main grain production areas has been continuously improving. The average Internet penetration rate increased from 0.25 in 2008 to 0.54 in 2018. (2) The agricultural ecological efficiency of China’s main grain production areas has gradually improved. The average value of agricultural ecological efficiency increased from 0.45 in 2009 to 0.79 in 2018. (3) The Internet development level in China’s main grain production areas and the continuous improvement of coordination and degree of coupling of the agricultural ecological efficiency show that the interaction between them has led to continuous improvements in the agricultural informatization development and agricultural green development. However, the coordination between the two still has significant room for growth, and there is a certain gap between the different regions.
Building construction tasks generate many environmental impacts during their execution. The assessment and comparison of the ecological effects of different construction tasks can aid in reducing ...emissions from these tasks. This study introduces an impact assessment methodology to assess the ecological effects of different building construction tasks according to the construction equipment used. In this study, global warming potential (GWP
100
), acidification potential (AP), eutrophication potential (EP), photochemical oxidation formation potential (POFP) and human toxicity potential (HTP) are considered as impact categories and evaluated at the global, regional and local levels. A case study of an administrative building in Egypt is used to validate the practicality of the developed model. The results demonstrate that the developed model can efficiently evaluate the ecological effects of construction tasks, and contractors can use it as a tool for choosing ecologically friendly construction strategies.
To facilitate the adoption of the circular economy (CE) in the architecture, engineering and construction (AEC) sector, some authors have demonstrated the potential of recent designs that take into ...account the sustainable management of an asset’s end-of-life (EOL), providing an alternative to the dominant designs that end with demolition. However, there is no review of the literature that encompasses a large range of sustainable designs in the current CE context. This paper provides a critical review of journal papers that deal with the barriers to implementing sustainable designs and approaches to the EOL management of assets that have the potential to fulfil the principles of the CE. Eighteen approaches related to prefabrication, design for change, design for deconstruction, reverse logistics, waste management and closed-loop systems were found. Through an analysis of the barriers that are common among these 18 approaches, we classified them into six different categories (organisational, economical, technical, social, political and environmental). Two Sankey diagrams illustrate the interrelation between the barriers, their categories and the 18 approaches. The diagrams clearly show that most of the barriers are common to multiple approaches and that most of the barriers relate to organisational concerns. The study gives a detailed map of the barriers that would help stakeholders from the AEC sector develop strategies to overcome the current obstacles in the shift to a CE.
This paper presents a fuzzy multi-criteria analysis approach for selecting of planning and design (P&D) alternatives in public office building. The Fuzzy Analytic Hierarchy Process (FAHP) method is ...used to determine the weightings for evaluation criteria among decision makers, including owners group, users group and experts group. The subjectivity and vagueness in the alternatives selection process is dealt with by using fuzzy numbers for linguistic terms. Incorporated the decision makers' attitude towards preference, a crisp overall performance value is obtained for each alternative based on the concept of Fuzzy Multiple Criteria Decision Making (FMCDM). A case study consisting of five alternatives, solicited from a public works agency in Taiwan, illustrates the effectiveness of the proposed approach.
In preparing geopolymer based on red mud (RM), preactivation processes that are generally energy-intensive are employed, including two indispensable steps, namely, calcination and fine grinding. A ...novel co-grinding preactivation method without calcination was proposed in this study. RM was pretreated by mix grinding with blended coal gangue (CG) (weight ratio of 8:2) for 20 min. The powdered mixture was characterized by alumina silicate dissolution efficiency test, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy. The corresponding geopolymer was also synthesized and characterized by XRD and scanning electron microscopy to assess the mechanical properties and polymerization reaction. Results showed that under co-grinding effect, the main alumina silicates of the RM/CG mixture were transformed into low-coordinated or low-polymerized phases. The phases were then dissolved in alkaline solution and repolymerized. Alkali activation with high compressive strengths completely formed dense amorphous geopolymer matrices. This work demonstrated that CG, as a milled conditioner, could efficiently expedite the preactivation of RM by grinding without calcinations. Moreover, an RM/CG-based geopolymer was successfully synthesized from the preactivated mixture.
•The polypropylene fibers improved the post-crack performance of the beams.•Higher peak loads were reached at fiber contents of 0.6% and 0.8%.•Both fiber pullout and fracture was observed during ...specimen testing.
Soil blocks are sustainable, low-cost, masonry materials that exhibit low resistance to bending. This study focused on experimentally investigating the influence of polypropylene fibers on the flexural performance and failure mechanism of cement stabilized soil blocks. Specimens were produced with different fiber mass proportions for comparison with specimens without fibers. Test results showed an improvement in post-crack flexural behavior and toughness of the fiber-reinforced specimens compared to the unreinforced ones. Depending on fiber content, specimens exhibited either a deflection softening or deflection hardening behavior during testing. Failure of specimens was characterized by both fiber fracture and pullout.
An investigation that combines both experimental tests and mesoscopic modelling is conducted to characterize the dynamic splitting-tensile behavior of coral aggregate concrete (CAC). Static and ...dynamic splitting-tensile strength and failure patterns of CAC with different uniaxial compressive strength (30–70 MPa) are tested by means of MTS machine and Split-Hopkinson pressure bar device, respectively. A three-dimensional (3D) randomly mesoscopic model for the simulation of the splitting-tensile strength and failure of CAC under different strain rates (1–200 s
−1
) is developed and validated by contrasting tested and numerical results. The experimental and numerical results indicate that the splitting-tensile strength and failure pattern are significantly affected by concrete strength and strain rate. The dynamic splitting failure mechanism that the damage outside the specimen is more serious than the inside, and the fracture in the center of the specimen is more severe than the edge, has been explained from the localized failure patterns of concrete and aggregates. Furthermore, it can be learned from the tensile dynamic increase factor of CAC is sensitive to strain rate significantly, which has a profound significance in the further investigation of reef CAC structures.
A chloride attack is one of the culprits for the structural deterioration of steel passivation film in the coastal environment, which greatly limits the sustainability of the materials in ...infrastructure. Since the passivation film is usually only a few nanometers to tens of nanometers, it is necessary to study methods at appropriate scales. To effectively assess the hazards of chloride ions, the nanoscale process of γ-FeOOH deterioration is revealed by reactive molecular dynamics and electronic structures. It is found that the perfect γ-FeOOH can not deteriorate and the defects can facilitate chloride attack. The Cl
−
is first adsorbed on the defects of γ-FeOOH, and then induces the Na
+
to form Cl-Na pairs. The vibration of Cl-Na pairs will weaken the interaction between the layers of γ-FeOOH and thus break the γ-FeOOH structure. The electronic structural analyses prove that the Cl ions have strong bonding with the hydroxyls of γ-FeOOH, but Na ions are the opposite. Therefore, the Cl and Na ions play the role of anchoring the γ-FeOOH surface and breaking the γ-FeOOH structure by vibration, respectively. The detail of nanoscale static and dynamic properties are also revealed. This phenomenon can be recognized as the first step in the structural deterioration of steel passivation films.
Green building materials have nontoxic properties and are made from recycled materials. This means they are, in most cases, created from renewable resources in comparison to non-renewable resources. ...This research aims to further improve the justification of green buildings and their materials. This is undertaken to determine the validity of such construction techniques. This research utilizes both qualitative and quantitative methods through five Australian case studies. The case studies, which are based on new and redeveloped structures, are selected via different geological locations and are evaluated via logical argumentation along with correlation research. Further, the research will address the problem by identifying a variety of green building materials that can be used to substitute non-green building materials. With careful comparisons among the five buildings, the green signs and implementation advantages and disadvantages will be evaluated. The result of this comparison will assist in improving the current education around the topic of green building and benefit the overall response to positive change within the construction industry. Although green building initiatives are not difficult to apply, they can be cost efficient. To maximize their cost efficiency, these initiatives need to be fully adopted. This includes the adaptation of specific building orientation, design, and sealing off penetrations to greatly improve passive heating and cooling. Further, the use of rainwater tanks also assists with energy efficiency by reducing the amount of mains water used. The utilization of natural lighting along with an advanced solar power system would further reduce the overall energy usage.
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