Geopolymer is an emerging low carbon cement-free binder that offers a sustainable and environmentally friendly alternative to ordinary Portland cement (OPC). Despite their outstanding environmental friendliness, geopolymer is still inherently exhibit brittle behaviour similar to conventional cement-based concrete. Recently, there is renewed interest to develop a new material combining geopolymer and Engineered Cementitious Composites (ECC) technologies. They named it as Engineered Geopolymer Composites (EGC). However, there are two major drawbacks associated with conventional geopolymer binder: firstly, handling of hostile, corrosive and viscous alkaline solutions; secondly, necessity for heat curing to improve geopolymerisation process and mechanical properties. To overcome such limitations, a new class of geopolymer composites known as “one-part” or “just add water” geopolymer was developed for this purpose.
The concept of ECC relies heavily on the micromechanics-based design principles, which provides guides for tailoring of fiber, matrix and fiber/matrix interfaces to attain desired tensile ductility. Through careful tailoring, the fiber volume fraction is usually remains moderate, typically less than 2.5%. Polyvinyl alcohol (PVA) fiber is the most common types of fiber used in ECC. To develop a cement-less EGC, a proper consideration on the geopolymer matrix design is essential. Research on EGC is still relatively new. Preliminary feasibility studies carried out on slag-based EGC [1] and fly ash-based EGC [2] shown very promising results with high tensile ductility over 4%. Studies on one-part EGC conducted by Nematollahi et al. [3] and Alrefaei et al. [4] further assure more detailed investigations are needed for potential applications of this technology in future eco-friendly civil infrastructure.
This paper presents the results of a preliminary investigation on the influence of precursor materials on the mechanical properties of one-part EGC. The aluminosilicate precursor materials used in this study consisted of combined fly ash (FA), ground granulated blastfurnace slag (GGBS) and quartz powder (QP). Sodium metasilicate anhydrous was used as the solid alkali activator to synthesize the ambient-cured one-part geopolymer composites. In order to minimize the matrix fracture toughness, all mixtures were prepared without addition of silica sand. All mixtures were designed with variations proportion of FA, GGBS and QP, amount of alkali activators and water contents. Mechanical properties were determined by compression and direct tension tests. Fresh properties and microstructure analysis of each mixtures were also studied and discussed.
The results indicate that combined GGBS with FA improve the reactivity of the mixture, compressive strength and enable possible ambient curing condition. Due to spherical nature of FA particle shape, best proportion between FA and GGBS in term of flowability was found at the percentage of 70:30 respectively. Increase on the amount of solid alkali activators used, reduce in the water contents and addition of QP could beneficially increase the compressive strength as well as uniaxial tensile cracking strength, ultimate strength and strain capacity. This is clearly reflected on the microstructure of the geopolymer gel, which showed more compact and denser morphology.

The increased awareness of the effects of ecological imbalances associated with construction and industry forced several corporate and governmental bodies to look at the avenues for sustainability over a broad spectrum in the 21^st century. Most of these industrial and other associations, both government and private, started to look for the path to sustainability in a wide variety of sectors ranging from energy, urban development, corporate, agriculture, food and even in fashion and to meet the requirements through the three known pillars of sustainability - environmental, societal and economic. Coming to Infrastructure, sustainability is a crucial part where the activities of design, construction, conservation of resources for future generations and produce lightweight resilient structures having high strength and performance which improves the life span of the structure. Sustainability towards infrastructure and its intricacies plays a tremendous role in the assessment methodologies and the governing principles have to satisfy the requirements of three pillars of sustainability without compromising the strength and performance of the structure. The present paper is an effort to present a comprehensive outline for the sustainability of resilient infrastructure, activities related to construction and prefabrication, its importance, and its assessment methodologies available presently. Policies like minimization of construction materials, energy conservation and use of construction and demolition waste, apart from industrial waste byproducts which intern reduces the impact on the environment and also minimizes the emission of CO2 are advocated. It is felt that innovative, environmentally friendly and appropriate utilization of materials based on effective research and developmental outcomes are needed. Apart from this the suitability, appropriateness and limitations of each of the assessment methodologies for ensuring an extended lifespan in particular for the infrastructure are discussed. The aim is to leave the smallest footprint while suggesting the possible avenues to achieve lasting structural facilities in all forms of infrastructure.

Sustainability Assessment (SA) is a method to support decision-making process through the evaluation of the system effectiveness, environmental integrity, economic valuation, and social implications. SA can be carried out through the application of life cycle-based techniques for quantitative assessment, or by performing a mainly qualitative approach via sustainability rating systems (SRS).

In the field of civil engineering many SRS have been proposed, all based on assigning point values to actions which are determined to contribute to the overall sustainability of the project. However, only few of these systems can be applied specifically to compare road pavements technologies and/or maintenance and rehabilitation strategies. This study focuses on adapting two of these tools: GreenPave, developed in US, and BE²ST (Building Environmentally and Economically Sustainable Transportation-Infrastructure-Highways), developed in Canada. The investigation consisted in evaluating the feasibility of increasing the amount of reclaimed asphalt (RA) in European wearing courses, by carrying out a comparative analysis of eight different mixtures, containing up to 90% of RA.

As anticipated above, the SA was performed using two SRS: GreenPave and BE²ST. Both tools allow to carry out a SA exercise by assigning a label to each compared alternative, from Gold to Bronze according to the final rating, however GreenPave limits the assessment to the asphalt mixtures technology development phase, while BE²ST allows to compare also road pavement maintenance strategies. Even if there are some similarities, the scores are assigned with different criteria. In fact, if GreenPave groups the sustainability goals into four categories (Pavement technologies, Material & Resources, Energy & Atmosphere, Innovation & Design Process), BE²ST judges the performance evaluating the Life Cycle Assessment for environmental aspects, the Life Cycle Cost Analysis for economic impacts, the traffic noise, the social costs, the social carbon costs and the recycling ratio. Furthermore, BE²ST expresses the results as percentage of the baseline: the label depends on the term of comparison.

In order to apply the former tool to the EU context, ECORCE M was used instead of PALATE for calculating environmental indicator; while the Social Carbon Cost was assessed by considering the European average annual salary. At first the study provides limits and benefits of the EU-adapted SRS, then a validation of the tools was performed by carrying out a SA of three case studies. As a result, both SRS provides similar trends of scores when compared with hot asphalt mixtures for wearing courses with no recycled materials; however GreenPave labels all the RA technologies as Gold or Silver, unlike the conventional asphalts which never meet the requirements for sustainability. On the other side, with BE²ST almost all the new mixtures achieve a label.

In conclusion, it can be stated that regardless of the SRS tools, maximizing the quantity of RA in hot mix asphalt for wearing courses, while guaranteeing the same level of durability, seems to be a more sustainable solution than not recycling at all. This is true for both a single intervention and by considering a 60 years maintenance strategy.

Textile reinforced mortar (TRM) are effective method of confining concrete elements to elevate the axial load resistance and upgrade the overall performance of concrete. TRM is a promising alternative for carbon fiber reinforced polymer (CFRP) which are commonly used in strengthening concrete and are known to be expensive since it requires huge amount of energy in processing these materials. Green technologies can be applied in this process following the same TRM principles of confinement replacing conventional cement or epoxy-based mortar and synthetic textiles towards sustainable concrete strengthening technology. This is through the utilization of geopolymer mortar reinforced with short banana fibers (BF) and long BFs as textiles. Geopolymer mortar presented in this paper is composed of fly ash and silica fume as binder, sand as filler, sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) as activator and BFs as reinforcement and textile. Geopolymerization generates significantly lesser carbon dioxide (CO₂) while BFs are known for having attractive mechanical properties, cost effective and abundant in nature for which making use of its fiber will significantly minimize the huge waste produced from banana plantations after a one-time fruit harvest only. The geotextile or geogrid used to wrap the concrete cylinder samples is made up of 2mm diameter long BF yarns with weights ranging from 150 to 450 grams per square meter that varies with grid sizes from 10mm, 15mm to 25mm for both orthogonal directions considering the lightweight characteristic of BFs. Twelve TRM designs were used to strengthen the concrete cylinders with three samples each. TRM design parameters varies with thickness of geopolymer mortar covering and the size of geotextile grids. Eighteen of the geotextiles used were coated with polymer to protect the fibers while the other eighteen geotextiles remained uncoated. A total of thirty-nine concrete cylinders samples cured within 28 days were prepared, for which 36 cylinders were confined with green TRM with different parameters while three of the plain concrete cylinders served as control specimens. This is to maximize the investigation on the potential of green TRM in confining concrete and to determine the variations in compressive strengths and mode of failures of confined and unconfined concrete specimens. Results highlighted notable enhancement in the mechanical properties of the modified plain concrete after 28 days of TRM curing using universal testing machine (UTM). Likewise, a confinement theory of the optimum TRM design was modeled mathematically to evaluate the effects of concrete confinement and overall load carrying capacity enhancement gained from additional strength transferred by TRM to the concrete element.

Building information modelling (BIM) is getting increasingly used in practice as a method of consistent and continuous usage of digital information in design, construction and operation of buildings [1]. During recent years, the infrastructure sector has been introduced to the established workflows, processes, and data models previously only focusing on the building sector [2, 4]. This contribution showcases a typical workflow as applied to a bridge model: the quality checking and quality assurance (QA/QC) of digital information delivered during the design phase.
A very important aspect of any information flow is ensuring received data’s compliance with predefined requirements. In the world of BIM, the Exchange Information Requirements (EIR) lists all necessary information to be delivered at handover, i.e., every element with its attributes, attribute types as well as constraints to values in attributes. The information author produces a BIM execution plan (BEP) which details the EIR as applied to the project considering the software solutions employed. The model is submitted in an agreed format, e.g., using Industry Foundation Classes (IFC) [3]. Checking rules shall be derived from the BEP and are used for automatic model checking of the delivered data from the BIM modelling process. Identified issues shall be reported back to the modeller using the BIM collaboration format (BIM) data format.
We showcase the QA/QC process on a bridge model from Sweden. The requirements were defined before the design commenced and shared with the design firm. For example, the EIR requires the length of an edge beam Längd (kantbalk) to be provided for the asset management system used by the agency. The BEP foresees this information to be provided within an IFC dataset, attached with a property set to an IfcBeam element. The property set shall be named ePset_BaTManKantbalkOccurence and the property K35: Längd (kantbalk). The model submitted to the stakeholder has been checked against the requirement with the following result: out of 15 beams in the delivered dataset, 13 pass and 2 fail the described check, since they don’t have the specific property set attached.
The example and the checking rules were prepared in the current official IFC4 version of the standard [3]. The scope of this version is building related with limited support for the infrastructure domain. Thus, many modelling decisions in BEP were suboptimal, frequently knowingly misusing an established concept or an IFC entity. The spatial container for the whole bridge was chosen to be IfcBuilding and showcases a work-around for the lack of better alternatives, whereas other such as the railing of the bridge modelled as an IfcRailing demonstrates good practice. Additionally, many elements had to be modelled using the placeholder entity IfcBuildingElementProxy and classified using less than ideal concepts, e.g., properties for objects defined in this project.
The IFC standard has been expanded over the course of the past years to provide better support for infrastructure specifics [4]. The authors call for its fast adoption in the industry to ensure semantically rich exchanges with little-to-none work-arounds needed.

The BIM (Building Information Modelling) is transforming the architecture, engineering and construction (AEC) industry everywhere in the world. In Sub-Saharan Countries, its spreading is just in an earlier stage while academics are working hand in hand with the local industry for its smooth implementation. In this context, the aim of this research is to provide an approach for designing industrial warehouses subjected to marine conditions using BIM. For this purpose, and considering our context, we make use of a methodology in seven steps:

• 1- Definition of BIM general requirements
• 2- Design of the 3D BIM architectural model
• 3- Design of thermal insulation
• 4- Design of the 3D BIM structural model
• 5- Coordination of 3D BIM models and interference detection
• 6- Creation of 4D BIM model by joining the schedule to the 3D BIM model
• 7- Creation of the 5D BIM model by joining the cost estimation to the 4D

More precisely:

• Definition of BIM general requirements for this type of construction project. Here we define the units, the language, the open standard for exchanging data, the BIM deliverables, the quality control process and how data sharing will be done and adopt a Level of Development 300;
• Design of the 3D BIM architectural model. Parametric objects (footings, walls, windows, beam, column…) are used to create the model, and the software used is Autodesk Revit Architecture 2018;
• Design of thermal insulation making use of CSTB (1975), Microsoft Excel 2010 Software and the previous BIM architectural model;
• Design of the 3D BIM structural model using Revit 2018 Platform, Robot Structural Analysis 2018 and IFC format;
• Coordination of 3D BIM models and interference detection with the software Autodesk Navisworks Manage; All possible clashes between the different models are corrected in order to get a consistent 3D BIM model;
• Creation of 4D BIM model by combining schedule (created with the software Ms. Project) of the project to each BIM objects of the 3D BIM model ;
• Creation of the 5D model that gives us the cost estimation of the elements built onsite and the element to be built at every step of the project (this calculation is done using Navisworks manage or intelligent BIM objects).

This methodology is applied for the design of a warehouse, dedicated to contain cocoa or coffee products requiring homogeneous thermo-hydroscopic setting in a marine environment of the industrial area of the deep sea port of Kribi (Cameroon), with a surface of 2000 m² and 11.2 m height. Preliminary results show that the proposed methodology can be easily implemented with available BIM software commonly used by engineers in Cameroon. This approach makes it possible to get quickly a consistent 5D BIM model of the industrial building, namely a comprehensive model which integrates data related to: architecture, structure, thermal insulation and planning of the industrial building.

Our research studies are moving forward in order to automatically generate costs related to the project using state of art approaches related to higher Degree BIM models and based on intelligent BIM objects.

Additive Manufacturing (AM) is process in which a three-dimensional component is produced by the consecutive addition of material. This technology, applied on a large-scale to cementitious materials, is known as 3D Concrete Printing (3DCP). Among the new technologies driving the fourth industrial revolution in the construction industry, 3D Concrete Printing (3DCP) is playing a key role. The typical process is made through robotic arms or gantries equipped with nozzles, similarly to contour crafting in other industries, where the printed object is obtained through the multiple deposition of layers. Despite 3DCP is appealing when addressed to specific items, as complex architectural shapes, the structural behavior and geometrical size are limitations difficult to over come. Upscaling the extrusion process to full sections, introducing a new concept of ultrafast and adaptable slipforming, is the access key to different domains of the industry, as infrastructures, where the increase in productivity results in social, economic and environmental benefits, that are not comparable to the niche where 3DCP is confined. As a matter of fact, the maintenance process of existing infrastructures is a very critical topic in most of the industrialized countries, worldwide. It is commonly recognized by the main players operating in the industry (professional engineers, owners, construction companies etc.) that, despite for new constructions the methodologies are quite evolved (i.e. development of the tunnel boring machines), in the maintenance area there is complete lack of technologies, making still impossible to industrialize the operations. This paper will present the Extruded Tunnel Lining Regeneration (ETLR) technology developed by HINFRA with the scope to automatically regenerate the lining of existing damaged tunnels directly at site. The ETRL processing train is a machinery consisting of several modular units, each solving a specific function. The increasing industrialization of set of operations, typically the demolition, the surface preparation, and the new lining phases, combined with the performances of the special concrete, allow to target productivity rates far from the traditional methods in use in the industry. This is made possible by the development of an extrudable eco-friendly Fiber-Reinforced Concrete (FRC) characterized by high early-age compressive strength and fast setting time, that is the other key aspect of the innovative technology implemented by HINFRA. “Tailored” technological issues, including e.g. the experimental determination of the friction between the extrudable mixes and formworks, will be discussed, together with a design validation related to a FRC tunnel lining, whose use could further exploit, through the significant reduction of ordinary reinforcement, the potentials of 3DCP.

With an increasing interest in the environmental issues, a variety of studies have been carried out to improve the sustainability of concrete pavements [1]. Use of structural fibers in pavement applications is one of the methods proposed to improve the carbon footprint of concrete pavements. As the fibers allow to produce concrete pavements with lower thickness and without conventional rebars [2] (which means lower use of materials), by increasing the cracking resistance, and flexural performance of concrete. However, the number of studies that numerically presents the benefit that could be obtained from macro fibers are still limited. This study has been carried out to examine how the use of polypropylene (embossed, 40 mm) fibers in varying amounts (0.25 – 0.50 – 0.75 – 1.00 %vol.) change the required thickness, cost, and environmental impact (CO2 emission) of concrete pavements. Selection of polypropylene fiber among its alternatives (steel, glass, carbon, etc.) was done by considering their common usage in slab-on-ground applications, which is due to their various advantages, such as ease of handling, competitive cost, and corrosion free nature.

To achieve the aim of the study, first an experimental study was conducted to determine the mechanical performance (compressive strength, modulus of elasticity, and flexural performance) of concrete mixtures with and without fibers. Then, thickness design for a sample road was done (according to IRC 58 [3]) by using the experimentally obtained material parameters, and specified thickness values were used to determine the amount of material (aggregate, cement, water, super-plasticizer, fiber) required to produce 1 m² pavement. In the last part, by using the amount of required materials and cost / CO₂ emission of unit products, cost and CO2 emission values were determined for each of the considered mixtures (for 1 m² pavement construction).

Based on the mechanical test results, used fibers did not considerably change the compressive strength, modulus of elasticity, and flexural strength of concrete mixtures. However, considerable improvements in the post cracking flexural performance were obtained for the fiber reinforced concrete (FRC) mixtures depending on the amount of fiber used. Despite the increasing cost (13.9 - 51.3 - 85.5 - 111.5 % increase for 0.25 – 0.50 – 0.75 – 1.00 %vol., respectively), decreased thickness requirements (5.2 - 9.6 - 14.0 - 19.7 % reduction for 0.25 – 0.50 – 0.75 – 1.00 %vol., respectively) and CO₂ emissions (8.3 - 9.9 - 11.6 - 15.1 % reduction for 0.25 – 0.50 – 0.75 – 1.00 %vol., respectively) were found for FRC mixtures compared to the plain one. Based on the results, despite the decrease in thickness requirement and CO₂ emission, material cost increases with increasing polypropylene fiber amount. It is worth noting here that the presented results are valid for the fibers used in this study, and use of different fiber types (with different raw materials (e.g. recycled fibers), surface properties, lengths, aspect ratios, etc.) might alter the results in varying amounts.

Funding: This research received no external funding.

Conflicts of Interest: The authors declare no conflict of interest.

References:

1. Ozturk, O.; Yildirim, H.; Ozyurt, N.; Ozturan, T. Evaluation of mechanical properties and structural behaviour of concrete pavements produced with virgin and recycled aggregates: an experimental and numerical study. J. Pavement Eng. 2022.
2. Ozturk, O.; Menekse, F.; Ozyurt, N. Usage of Fiber Reinforcement for Concrete Pavement Applications and Implication of Fiber Reinforcement to the Thickness Design. International Conference on Cement-Based Materials Tailored for a Sustainable Future-(CBMT). Istanbul, Turkey. 2021.
3. Indian Roads Congress. Guidelines for the design of plain jointed rigid pavements for highways (IRC 58). New Delhi, India, June 2015, Fourth revision.

Interdisciplinary collaboration and communication are two essential aspects of Building Information Modeling (BIM). Current practice and international standards rely on exchanging entire domain models, which are managed as separated files and coordinated in a primarily manual fashion. The concept lacks version control, as the granularity of change tracking remains on the level of complete monolithic files. Hence, high manual effort is necessary to coordinate model modifications across the domains involved in a project.

To overcome the limitations addressed, the keynote presents a novel approach that enables modification tracking on object level instead of tracking monolithic model files. As BIM models contain not only objects but also various dependencies forming a complex network structure, formalisms of graph theory and graph transformation are applied to identify and deploy model changes in a vendor- and schema-neutral fashion. The communication among project partners is ultimately implemented using event-driven network architectures, which provide a flexible means to realize scalable asynchronous collaboration. Once an authoring party reaches a new shareable state of its discipline model, an update event is raised and deployed through a central project hub. Each event contains a set of transformation rules and additional information relevant to project management purposes. Applying the transformations to an outdated model copy, concurrency among all existing replicas of a particular discipline model is obtained again. As a key advantage, the updates are much smaller compared to repeatedly exchanging entire BIM models. Furthermore, the approach provides a responsive and scalable system where each design unit can subscribe to specific events like modifications of specific object types or models of a particular discipline. Finally, the approach fits into existing standards of model-based collaboration such as ISO 19650 or the concept of Information Containers for linked Document Delivery (ICDD) defined in ISO 21597.

The application of the proposed collaboration environment is demonstrated using BIM models implementing the Industry Foundation Classes (IFC) as their underlying data model.

References

Esser, S., Vilgertshofer, S., & Borrmann, A. (2021). Graph-based version control for asynchronous BIM level 3 collaboration. EG-ICE 2021 Workshop on Intelligent Computing in Engineering, 98–107. https://doi.org/10.14279/depositonce-12021

Esser, S., Abualdenien, J., Vilgertshofer, S., & Borrmann, A. (2022). Requirements for event-driven architectures in open BIM collaboration. 29th International Workshop on Intelligent Computing in Engineering.

Acknowledgments: We gratefully acknowledge the support of the German Research Foundation (DFG) for partly funding the project under grant FOR2363. Additionally, we would like to thank Autodesk, Inc. for their financial support.

Conflicts of Interest: The authors declare no conflict of interest.

It is clearly a huge benefit for infrastructure monitoring, inspection, and management when a digital twin (DT) is developed to represent a real physical infrastructure. One of a backbone of the DT is as-is three-dimensional (3D) geometric models of physical assets, which are used to integrate real-time information of the physical assets and are fundamental components for modelling and simulation to predict response of infrastructure. In the DT concept, the digital model must be automatically update changes of physical infrastructure accurately and timely. Today, laser scanning sensors and cameras integrated into laser scanners, drones and other survey equipment allowing to capture 3D topographic information of objects’ surfaces in a 3D space with different level of details and accuracy. As such, 3D point clouds are to be a fundamental resource to create 3D geometric models for DT. Automatically generating digital models from the 3D point clouds presents high challenges due to adverse quality and quantity of data points, massive data points, and highly complex geometries of objects and a 3D scene. Moreover, in practice, existing workflows to achieve detailed precise 3D geometric models of the physical assets are mostly based on human work implying time-consuming, costly, and human errors. This paper proposes a framework using both spatial information of point clouds and contextual knowledge of objects to automatically extract point clouds of individual surfaces of objects of infrastructure (e.g., buildings and bridges). Contextual knowledge can include lower and upper bounds of dimensions of the objects, and a geometric relationship with adjoined objects. The main goal of the use of contextual knowledge is to support in estimating input parameters, to roughly extract point clouds of interest, and to filter unrealistic objects to be recognized. By integrating contextual knowledge into the framework, only a subset containing the point cloud of each object of interest need to be processed to extract the surfaces, the proposed framework can handle large bridge data sets. Once the point cloud of individual surfaces of each structural component are available, the 3D models of the structure can be created, or surface damage can be identified. Buildings and bridges are selected as case studies to demonstrate the proposed framework.

Funding: This study was funded by the generous support of the European Commission through H2020 MSCA-IF, “BridgeScan: Laser Scanning for Automatic Bridge Assessment”, Grant 799149.

Acknowledgments: The authors also thank Dat Hop Company Limited, Ceotic., JSC and GeoInstinct Vietnam (https://www.geoinstinct.com) for their providing the laser scanning data.

References

1. Truong-Hong, L. and Lindenbergh, R., 2022. Automatically extracting surfaces of reinforced concrete bridges from terrestrial laser scanning point clouds. Automation in Construction, 135, p.104127.
2. Truong-Hong, L. and Lindenbergh, R., 2022. Extracting structural components of concrete buildings from laser scanning point clouds from construction sites. Advanced Engineering Informatics, 51, p.101490.
3. Truong-Hong, L. and Laefer, D.F., 2015. Quantitative evaluation strategies for urban 3D model generation from remote sensing data. Computers & Graphics, 49, pp.82-91.