Documents published in Scipedia

• Comparison of Non-calcined and Calcined Red Muds from Different Sources as Potential Supplementary Cementitious Material

  S. Chen, A. Ghani Razaqpur

  DBMC 2023.

  
  

  Abstract

  Red mud (RM) is a hazardous by-product of alumina refining processes. Due to its high alkalinity, large specific surface area, and complex and variable composition, RM is hard to treat or utilize on a large scale. To date, more than 4 billion tons of RM have been stockpiled globally and is still growing by more than 120 million tons annually. Many investigations have focused on the largescale utilization of RM as a construction material, either in its virgin form or after heat treatment. However, the huge differences among the chemical/mineralogical compositions of RMs due to differences among bauxite ores from different sources and/or different refining processes, it is difficult to prescribe a unique process for activating RM cementitious/pozzolanic properties. The present study aims to identify the key chemical and process-dependent factors that influence the cementitious/pozzolanic properties of RM. Two types of RM from different sources are investigated to determine the effects of the chemical/mineralogical composition, the alumina refining process, and calcination on the mineralogical phases and compressive strength of mortar cubes made with ordinary Portland cement (OPC)- RM blended cement. Mortar made with 15 wt.% OPC replaced by one type of virgin RM produced by the Bayer’s process was found to have better strength than a control mortar made with 15% OPC replaced by sand, which indicates that this RM had cementitious/pozzolanic property without requiring heat treatment. On the other hand, the RM produced by the bauxite calcination method needed heat treatment to improve its pozzolanicity, but, despite the improvement, mortar made with its optimally treated form had lower 91-day compressive strength than the companion control mortar made with extra sand as RM replacement. The compressive strength of mortars made with calcined RM was not only affected by the phase changes of the virgin RM properties brought about by calcination but also by changes to its physical.

  Abstract
  Red mud (RM) is a hazardous by-product of alumina refining processes. Due to its high alkalinity, large specific surface area, and complex and variable composition, RM is [...]

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• Rebar-matrix Interface in Extrusion Molded Cementitious Filaments

  R. Yang, Q. Zeng, Z. Wang

  DBMC 2023.

  
  

  Abstract

  Extrusion molding enables automatic construction through the pattern of material addition. The unique molding would result in several features that are different from those in conventional framework molding, such as weak interlayer bonding and a laminar structure with high anisotropy. To strengthen the interlayer bonding, reinforcement is often implanted to penetrate through the extrusion molded filaments (EMF). However, different from the pre-implantation of reinforcement before concrete casting, the post-implantation of reinforcement in EMF may trigger the problems concerning the interface bonding between reinforcement and material matrix. In this work, saddle stitches, a type of Ushape rebar or fiber, are taken as an example to demonstrate the effect of the post-implantation of reinforcement on the interfacial structure between the rebar and EMF matrix. X-ray computed tomography (XCT) is employed to non-destructively probe the post-implanted saddle stitches as well as the surrounded EMF materials. Regions of interest (ROI) are set on the rebar-matrix interfaces to elaborately analyze the material or defect distributions around the saddle stitches. Results demonstrate that insufficient material filling is observed at the outboard of the U-shape rebar, while material pressing is shown at the inboard. Large defects unevenly form in the rebar-matrix interface. Mechanisms of the observations may be ascribed to the low flowability of EMF materials that can hardly migrate to the rebar-matrix interfacial gaps spontaneously. The findings would deepen the understandings in rebar-matrix interfacial structure of EMF with post-implantation of reinforcement.

  Abstract
  Extrusion molding enables automatic construction through the pattern of material addition. The unique molding would result in several features that are different from those [...]

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• Effectiveness of Paraffin-based Curing Compound for Mitigation of the Plastic Shrinkage and Related Cracking of the 3D-printed Concrete Elements

  S. Markin, V. Mechtcherine

  DBMC 2023.

  
  

  Abstract

  3D-printed concrete elements are highly vulnerable to early-age shrinkage and cracking compared to conventionally cast concrete elements. Material compositions of printable concretes and complete renunciation of shuttering are responsible for accelerated capillary pressure build-up, leading to volumetric constructions of the 3D-printed layers at a very early age after extrusion and enhanced shrinkage at a later age. Shrinkage-induced cracks can severely impair the durability and appearance of 3D-printed concrete structures. The study at hand analyses the efficacy of the paraffin-based curing agent for reducing the shrinkage and cracking of 3D-printed elements and structures. Development of the temperature and capillary pressure, as well as shrinkage strains, were reported for the cured and uncured specimens. The study results show that applying paraffin-based curing agents can considerably reduce shrinkage-indued deformations of the 3D-printed elements produced even under extreme environmental conditions.

  Abstract
  3D-printed concrete elements are highly vulnerable to early-age shrinkage and cracking compared to conventionally cast concrete elements. Material compositions of printable [...]

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• Effect of Delayed Addition of TEA on the Performance of Cement with Different Sulfate Carriers

  Z. Lu, X. Peng, Z. Sun, D. Stephan

  DBMC 2023.

  
  

  Abstract

  Concrete 3D printing is one promising technique used for future construction. However, a bottleneck limiting this technology's rapid development and practical application is the conflicting requirements for concrete properties before and after printing. Hence, the application of the accelerator and a deep understating of its working mechanism is becoming more and more important. As one commonly used accelerator, triethanolamine (TEA) has the advantage of low dosage and high efficiency to reach a fast setting. However, it is still unclear how the delayed addition of TEA affects the performance of cementitious materials. Besides, it is found that the different types and combinations of sulfate carriers can significantly affect the performance of TEA on cement hydration. However, the combined effect of different sulfate carriers and different addition times of TEA on the hydration process of cement paste is also unclear. The effect of different TEA addition times on the hydration and setting performance of cement pastes containing different types and combinations of sulfate carriers were thoroughly investigated in this study. It is found that, depending on the types of sulfate carriers inside, the different addition times of TEA can significantly affect the hydration and setting performance of cement paste. Specifically, to artificial cement (ArC) prepared with hemihydrate (HH), the different TEA addition times do not affect the setting performance of cement paste. To ArC with the two sulfate carriers of anhydrite (AH) and HH, a flash setting was observed when the TEA was added simultaneously. However, a delayed addition of TEA for just 5 min can make the setting performance back to normal. To ArC with only AH, a longer addition time of 15 min is needed to eliminate the flash setting behavior. This phenomenon could be originated from the competed interaction of sulfate ions released from sulfate carriers and TEA with the aluminate phase contained in the clinker.

  Abstract
  Concrete 3D printing is one promising technique used for future construction. However, a bottleneck limiting this technology's rapid development and practical application [...]

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• Adapting Construction and Demolition Waste to Circular Building Materials and Evaluation of Life Cycle Environmental Impacts

  A. Kul, E. Ozcelikci, B. Furkan Ozel, G. Yildirim, A. Ashour

  DBMC 2023.

  
  

  Abstract

  Upcycling of construction and demolition wastes (CDWs) into value-added building materials that can be used for rapid construction and housing in developing countries and disasterprone areas is important and offers a fast, cost-effective, and eco-friendly solution. The objective of this study is to investigate the feasibility of using different-size recycled concrete aggregates (RCAs) in geopolymers made entirely from CDW-based masonry components including hollow brick (HB), red clay brick (RCB), and roof tile (RT) as precursors. To improve the strength development, thermal curing was applied to the developed geopolymer mortars. Compressive strength test was used for mechanical characterization. To assess the environmental impact of geopolymer mortars, a cradle-to-gate life cycle assessment (LCA) was carried out. Findings revealed that RT-based geopolymer mortars were with the highest compressive strength level reaching 66.2 MPa based on different mixture and curing parameters. Compressive strength increased with the reduction in the maximum RCA size. According to LCA analysis, CDW-based geopolymer mortars resulted in similar strength but significant reduction in CO2 emissions (up to 60%) and are with comparable energy consumption to the Portland cement-based mortars.

  Abstract
  Upcycling of construction and demolition wastes (CDWs) into value-added building materials that can be used for rapid construction and housing in developing countries and [...]

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• A Conceptual Model for Assessing Circularity Potential of Building Materials at the Product Manufacturing Stage

  N. Tharaka Dharmasiri Pathberiyage, E. Delzendeh, F. Cheung, M. Mateo Garcia

  DBMC 2023.

  
  

  Abstract

  The construction industry presently accounts for 30% of natural resource extraction and 25% of solid waste generation. The prevailing economy is “Linear” which is summarised as take-makedispose. On the contrary, the “circular economy” model is a systematic model to restore, regenerate and expand the lifecycle of materials. Most of the existing circularity assessment methods are focused on the end-of-life wastage of building materials while neglecting resource consumption and wastage at the product manufacturing stage. Further, these methods only consider direct material flows for assessing the circularity potential of building materials and overlook the indirect material flows associated with product manufacturing. There is a need to develop metrics to assess the circularity performance of building materials more holistically. Therefore, this study proposes a conceptual model to assess the circularity potential of building materials by analysing both direct and indirect material flow processes of the product manufacturing stage including raw material extraction, transportation, and manufacturing. The method used to design the conceptual model includes a comprehensive literature review in two stages. First, the existing circular assessment methods are reviewed to identify the methods used for assessing the circularity potential of building materials. Secondly, the circularity options are explored to develop the circularity metrics. According to the findings of this study, in the absence of a comprehensive method to assess the circularity potential of building materials, the life cycle assessment and material flow analysis are the most prominent circularity assessment methods used. Furthermore, circularity options such as industrial waste (by-products), biodegradability, biofuels, renewable energy, reusability, recoverability, recyclability and product life span are identified as the circularity metrics for building materials at the product manufacturing stage.

  Abstract
  The construction industry presently accounts for 30% of natural resource extraction and 25% of solid waste generation. The prevailing economy is “Linear” which [...]

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• State-of-Art of Construction 4.0: An Academia Vs Industry Comparative Study

  W. Ahmad, S. Azhar

  DBMC 2023.

  
  

  Abstract

  The manufacturing industry is experiencing the 4th Industrial Revolution, also known as Industry 4.0. It encapsulates cyber-physical systems (i.e., combining sensing, computation, control and networking into physical objects and infrastructure) integrated towards digitalization and automation of the manufacturing sector. The construction industry has also benefited from these technologies, which go by Construction 4.0. Despite the construction industry often being blamed for its reluctance to implement emerging technologies and non-traditional management methods, recent research attempted to integrate Industry 4.0 emerging technologies to keep up with the manufacturing sector. This shows that academia and industry need each other’s hand-in-hand support in order to implement these technological advances. This study investigates the status of Construction 4.0 technologies adoption in academia and industry in the United States of America (USA) and measures the level of collaboration. Relevant data is collected via web-based questionnaire surveys that are distributed to academia and industry professionals within the USA to inquire about the status of construction 4.0 technologies and their adoption rate. The collected data are analyzed and important findings are reported in this paper. The results show that around 61% of the professionals from academia and 33% from industry are fully or somehow familiar with the term – ‘Construction 4.0’. There has been significant adoption of BIM, laser scanners, and drones in each sector. The rest of the technologies show potential in upcoming years, and academia and industry have methods in place of updating the workforce on new technologies. However, a lack of collaboration has been observed as 50% of the respondents reported no ongoing or past research projects between academia and industry in this domain. It is hoped that the findings of this research will help both academia and industry to join forces to modernize the construction industry.

  Abstract
  The manufacturing industry is experiencing the 4th Industrial Revolution, also known as Industry 4.0. It encapsulates cyber-physical systems (i.e., combining sensing, computation, [...]

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• Reality Capture (RC) Technology for Drywall Installation: A Scan-toPrefab Approach

  S. Alathamneh, J. Liu, S. Azhar, R. Burt

  DBMC 2023.

  
  

  Abstract

  Drywall, also known as gypsum board, sheetrock, or plasterboard, is a widely used building sheathing material in the US and Canada to create interior walls and ceilings. Typically, the design and construction documents of a project exclude detailed information about the layout of drywall sheets on interior surfaces. Such information is left to the drywall installation crews to determine solely based on their experience. This inconsistent approach often results in substantial rework and waste of material in the field. The construction industry has seen a significant increase in the adoption of Reality Capture (RC) technology in recent years, with the goal of improving the quality and productivity of various construction activities. This research aims to investigate the implementation of RC technology, explicitly Terrestrial Laser Scanning (TLS) and Structure from Motion (SfM, also referred to as photogrammetry), in drywall installation. The research team has developed a framework that utilizes RC tools to capture the as-built information of the framing members of interior walls and penetrations of the MEP systems and uses these RC data to develop prefabricating shop drawings in a Building Information Modeling (BIM) platform for drywall cutting and installation. This framework has been tested and studied on active construction project sites. The preliminary findings indicate that this framework has the potential to lead to a more precise and efficient drywall installation process. This paper also proposes a process model for the execution of the proposed framework for improving drywall installation.

  Abstract
  Drywall, also known as gypsum board, sheetrock, or plasterboard, is a widely used building sheathing material in the US and Canada to create interior walls and ceilings. Typically, [...]

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• Lateral Behavior of Modular Steel Buildings with Diaphragm Connections

  X. He, Y. Wei

  DBMC 2023.

  
  

  Abstract

  Modular steel buildings are increasingly popular due to their high level of industrialization. Corner-supported modular steel buildings are typically connected by inter-module connections at the corners of each module without continuous diaphragm slab. Therefore, rigid diaphragm assumption could not be adopted when designing modular steel buildings as in-plane deformation of the slab level is significant. To address this issue, the present study introduces diaphragm connections along the edges of modules at the floor slab levels. Then the lateral behavior of modular steel buildings with and without diaphragm connections is evaluated, as well as when a rigid diaphragm is assumed in the structures. The effect of diaphragm connection on lateral behavior of modular steel building under different parameters is discussed, including modular aspect ratio, number of modules in one storey, bracing system, and number of storeys. It is concluded that using diaphragm connections could improve the lateral behavior of modular steel buildings and simplify the design process.

  Abstract
  Modular steel buildings are increasingly popular due to their high level of industrialization. Corner-supported modular steel buildings are typically connected by inter-module [...]

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• Investigation of the Initial Quality of Robotic Tile Installation Based on Coupled Eulerian-Lagrangian Approach

  K. Wu, Y. Zhang, X. Kong, S. Zhang

  DBMC 2023.

  
  

  Abstract

  In this study, the initial quality of robotic tile installation under various construction parameters and material properties of adhesive were investigated based on the fluid–structure coupling construction models for the first time. First, the models of adhesive application and tile leveling were developed based on the coupled Eulerian–Lagrangian approach. Then, on the basis of these models, various patterns of adhesive application, types of tile leveling loads, numbers of adhesive strips and yield stresses of adhesive were simulated and their influence laws on the initial quality of robotic tile installation were analyzed. Finally, the influence mechanisms of these parameters on the installation quality were revealed in terms of the spacing between adhesive strips, tile rebounding, contact areas and defect distribution. Results showed that the adhesive with horizontal application possessed smaller plastic deformation, kept stable shape of strips and distributed at equal spacing, compared with the one with vertical application. In contrast to a single compression load, its couplings with vibration loads were beneficial to the reduction of tile rebounding. Among the coupling loads, the coupling of shear vibration with compression considerably increased the tile–adhesive contact area until no interfacial defect appeared. The increase of the number of adhesive strips exerts few effects on the installation quality, including slight increases of contact areas as well as diminished interfacial defects. In the case of relatively low and high yield stresses of adhesive, the shear vibration effects were respectively large and small which decrease the installation quality.

  Abstract
  In this study, the initial quality of robotic tile installation under various construction parameters and material properties of adhesive were investigated based on the fluid–structure [...]

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