With the rapid advancement of urbanization in China, a huge amount of construction and demolition wastes (CDW) are generated. Recycling CDW into subgrade materials is a promising way to process these ...wastes, with significant environmental and economic benefits. But very little work has been done in this field. Therefore, based on a CDW subgrade construction case in Beijing, the physical and chemical properties of the CDW materials were analyzed. Then the construction procedures of the CDW subgrade were presented, and a series of tests (compaction degree test, settlement observation, Portable Falling Weight Deflectometer test) were carried out. At the same time, the effects of different loose paving thicknesses, cycles of strong vibration on the subgrade performances were assayed. Subsequently, grading analysis of the CDW particles, plate load test and Beckman beam deflection test were performed to evaluate the construction quality. According to the test results, the construction technologies of the CDW subgrade, such as the optimum loose paving thicknesses and cycles of strong vibration, were determined. And then, the post-construction settlement monitor and radar survey were conducted for subgrades filled with CDW and soil to further analyze the applicability of CDW. The results show that recycled CDW aggregates with proper grading and strict construction technologies perform well. The subgrade filled with recycled CDW has a smaller deformation than that of the soil subgrade. Finally, the life cycle assessments (LCA) of two treating schemes of CDW were conducted to analyze the environmental benifits: recycling utilization as subgrade materials and directly landfilling. If the subgrade is filled with the recycled CDW aggregates, CDW will be consumed in large quantities and the environmental impactions of eutrophication and ecotoxicity can be reduced obviously.
Building information modelling (BIM) has significantly influenced the construction industry. However, the existing BIM tools and frameworks within prefabricated buildings are minimal. This research ...study aims to identify the opportunities and barriers of integrating BIM in the Australian prefabrication industry. The research was carried out using a mixed method of literature review and questionnaire survey with 30 indudstry professionals. The literature review identified the key challenges associated with prefabricated buildings including construction discipline-specific, fabrication-specific issues and communication-specific issues. The survey results proved that the most significant BIM opportunities are minimizing design errors and discrepancy of final product model between designers and manufacturers and increasing mass customization. The study revealed that seamless and timely information exchange among key project stakeholders via a BIM system was identified as the most critical success factor to adopt BIM in the prefabrication industry. This research provides practical insights into how to utilize BIM effectively for prefabrication in the housing sector. The survey results document the opportunities and barriers to BIM integration and provide professional insights on how BIM can benefit the prefabrication. The study contributes to the body of knowledge on enhancing the productivity/practice of prefabrication through BIM integration within the Australian housing context.
The Three Gorges Project on the Yangtze River is a key pillar project for harnessing, developing, and protecting the Yangtze River. It is the world’s largest water conservancy complex as well as a ...landmark project representing the great rejuvenation of the Chinese nation. This section presents the case study of the Three Gorges Project. First, the project highlights and characteristics were summarized. Second, the survey and design, engineering construction, and scientific and technological research and design were presented. Third, the operation benefits of the Three Gorges Water Conservancy Complex were discussed. Finally, engineering pictures are provided.
Adoption of digital information tools in the construction sector provides fertile ground for the birth and growth of companies that specialize in applications of technologies to design and ...construction. While some of the technologies are new, many implement ideas proposed in construction research decades ago that were impractical without a sound digital building information foundation. Building Information Modelling (BIM) itself can be traced to a landmark paper from 1975; ideas for artificially intelligent design and code checking tools date from the mid-1980s; and construction robots have laboured in research labs for decades. Yet only within the past five years has venture capital actively sought startup companies in the ‘Construction Tech’ sector. Following a set of digital construction innovations through their known past and their uncertain present, we review their increasingly optimistic future, all through the lens of their dependence on digital information. The review identifies new challenges, yielding a set of research topics with the potential to unlock a range of future applications that apply artificial intelligence.
•Start-ups have significant advantages over construction companies in Construction Tech innovation.•Construction Tech innovations are dependent on digital building information.•BIM provides digital building information, but there are still problems.•Semantic enrichment of BIM models is a central research challenge.•BIM representations suitable for AI are another major challenge.
There are many challenges in the construction of large-diameter tunnels, such as low efficiency of manual construction and poor safety. To solve the problems, a multi-functional arch installation ...machine, an auxiliary arch installation machine and matching devices of fabricated arches are developed. A new mechanized construction technology of fabricated arches is put forward. The numerical calculation and laboratory experiment are carried out on the mechanics mechanism of the I-steel arch in the mechanized construction process. The results show that the maximum stress value appears at the arch skewback and vault. In order to reduce the deformation of the key parts in the process of the arch installation, the skewback is reinforced to increase the local strength. In addition, the method of the manipulator with splint to lift the arch is proposed to reduce the stress concentration of the arch vault. Based on the above research, the application for mechanized construction of the fabricated arch is carried out on site, and both of the construction efficiency and the safety are significantly improved.
•A mechanized construction technology of fabricated arch for tunnels is proposed.•Mechanical mechanism of the construction process for fabricated arch is revealed.•The design method to ensure the overall stability of the arch is proposed.•The proposed technology and method are validated in a large-diameter tunnel.
The technological development of construction robots is underway globally. However, current development activities face significant uncertainties, particularly in terms of the definition and ...management of system requirements, which are primarily based on vague assumptions about the future. Thus, a new tool is required to grasp how construction robots—and their surrounding ecosystems—will be used. This research adopts an unprecedented scenario-based approach to develop and analyze future alternatives for construction robotics in a systematic manner. Hong Kong “toward 2035” is used as an initial test case, and four scenarios of the robot ecosystem, i.e., “Bottleneck,” “Age of Iron Worker,” “Dynamic Co-evolution of Robotization and Modularization,” and “Rise of the Robots,” are developed from evidence-based analysis. Scenarios highlight the crucial role of workers for construction robot utilization. Driving forces, opportunities, and challenges are identified for elaborating strategies under each scenario. The integrated scenario approach and findings lay an important foundation for systems engineering processes in construction robotics to develop a new tool for structuring system context and specifying system requirements.
•An integrated scenario approach is proposed for the future of construction robotics.•The scenario approach envisions future efforts to structure contexts of robot development.•The Hong Kong construction industry is applied as an initial test case.•Four scenarios are developed to provide narratives of utilizing construction robots.•Scenarios highlight the crucial role of workers for construction robot utilization.
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•An in situ heavy metal removal strategy by MMOGs in actual wastewater was proposed.•In situ method realized full exposure and generation additional of binding sites.•The adsorbed ...MMOGs can be reutilized for Sb(V) capture.
Metal-organic gels (MOGs) as outstanding heavy metals adsorbents suffer the problems of ex situ construction and not being able to reutilize, which restricts the widespread applications. To deal with this challenge, an in situ ultrasound-assisted technology integrated adsorbent fabrication with heavy metals removal in actual wastewater was firstly proposed. Characterizations analyses showed that the multivariate MOGs (MMOGs) was successfully constructed in industrial wastewater and simultaneous obtained a superb removal efficiency of 97.2%, 95.3% and 98.1% for Cu(II), Cd(II) and Cr(III), and the treated wastewater can reach the effluent standard. X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculation indicate that MMOGs obtained the most stable structure owing to the most stable binding energy, mainly attributed to the interaction between Cu(II) and − COOH of gelators that generates additional bonding sites for capturing Cd(II) and Cr(III) during the synthesis of adsorbent. Furthermore, we successfully show the possibility to reuse the adsorbed MMOGs in the oxyanions contaminated water, and it exhibits satisfactory removal capacity for Sb(V) with favorable biodegradability. This study provides a new insight and promising model for actual heavy metal wastewater treatment as well as resource utilization.
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•Fluorinated CdS/MoS2/ZnS nanocatalyst for hydrogen production is prepared.•Zn(OH)F nanoflowers are used as a multifunctional platform during synthesis.•Zn(OH)F limits the growth of ...CdS/ZnS nanoparticles and supplies F− ions.•The rapid capture and transfer of charges by MoS2 promotes hydrogen production.
The design and synthesis of highly efficient photocatalysts for hydrogen production via morphological engineering and channel construction technology based on photogenerated carrier transfer is an effective method for solving the energy problem and reducing environmental pollution. However, developing inexpensive semiconductor catalysts with high photocatalytic hydrogen evolution activity remains a challenging task. Herein, fluorinated CdS/MoS2/ZnS nanoparticles (CMZS NPs-F) with a precise surface distribution were prepared using Zn(OH)F nanoflowers as a multifunctional platform, for the efficient photocatalytic hydrogen production. Zn(OH)F not only limited the growth of CdS/ZnS NPs, but also provided F− ions to accelerate the carrier interfaciale transfer. Meanwhile, the rapid capture and transfer of charges by MoS2 increaed the hydrogen production rate of CMZS NPs-F to 11902 μmol·g−1·h−1, which was 13.9 times higher than that of CdS/ZnS. The results of experimental studies and density functional theory calculations that the observed increase in the hydrogen production rate was mainly due to the larger number of active sites, lower e-–h+ recombination efficiency and higher photogenerated charge transfer efficiency of CMZS NPs-F. This study provides deep insights into the photogenerated charge separation path and highly efficient catalytic hydrogen production.
With its advantages, prefabricated building has become a new development trend in the construction industry and has been vigorously promoted. However, the construction problems in its construction ...process have not been effectively solved. Prefabricated components have blind spots in the connection, rebar positioning is difficult to achieve accurate, when hoisting, the position of tower cranes is uncertain, and the sequence of using tower cranes is not clear for each shift and group, the layout is not reasonable, the adverse effect of construction environment is not considered, which affects the transportation and connection of components on roads and other issues. The development of interactive visualization transforms data information into a three-dimensional view with obvious visual effects, enhancing the information exchange between users. Through a large number of literature collection, the existing prefabricated building construction methods are summarized and analyzed, knowing that there are few studies that combine interactive visualization with prefabricated building construction technology. This paper tries to apply interactive visualization technology to the construction process of prefabricated buildings, and organically combine. Building information modeling technology and related technology with construction technology, through the establishment of virtual information model to achieve the purpose of visualization, building parts model information base, to achieve real-time interaction between users and building model information. Combined with the construction site conditions to determine a reasonable and feasible structure form, optimize the construction technical scheme, and then effectively improve the construction quality, achieve visual management of the construction process, promote the construction of assembly building information and digital level.
Industrialized construction technology (ICT) is widely used and becoming the new green construction method, but its development is being hindered by lack of innovation. To improve this, stakeholders ...are endeavoring to develop more innovative methods by inter-organizational collaboration. Despite its extensive use by other industries such as manufacturing, little is known of how to successfully apply collaborative innovation to ICT. This paper develops a method for studying the effects of a variety of aspects of existing collaborative relationships for ICT innovation using a combination of social network analysis (SNA) and structural equation modeling (SEM). A set of hypotheses are proposed concerning the expected influence of SNA factors of interaction frequency, emotional intensity, reciprocal exchange, network size, network density, centrality, relationship strength, network position, promotion, enterprise scale, nature and experience on collaborative innovation. Using questionnaire data obtained from a large sample of practitioners, SEM is then used to identify the key indicators involved and the extent of their effects on innovation. The paper constructs a collaborative ICT innovation relationship model in which the strengths of the interaction paths between stakeholders are obtained. With a single exception, this confirms all the hypotheses. Most of the SNA-based a priori hypotheses are shown to be well supported, which indicates the suitability of the SNA concept in developing collaborative ICT innovation. SNA is therefore confirmed as providing a suitable conceptual basis for the modeling and analysis of ICT innovation relationships. From this, a set of recommendations are provided to guide operating companies, designers and contractors in improving their collaborative innovation efforts. The results enable suggestions for enhancing collaborative ICT innovation capacity to be advanced to promote the interaction between stakeholders and the occupation of strategic positions. Although the study is carried out in the context of China’s prefabricated housing construction, the methods can be adopted in the broader global community.
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