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The construction industry consumes over 32% of the annually excavated natural resources worldwide. Additionally, it is responsible for 25% of the annually generated solid waste. To become a more sustainable industry, a circular economy is necessary: resources are kept in use as long as possible, aiming to reduce and recirculate natural resources. In this paper, the investigation focuses on pedestrian truss bridges of the types Warren and Howe. Many pedestrian bridges currently find themselves in their end-of-life phase and most commonly these bridges are demolished and rebuilt, thus needing a lot of new materials and energy. The aim is thus first and foremost to reduce the amount of necessary new materials. For this reason, a design tool will be created, using the software ‘Matlab’, in which truss bridges can be evaluated and compared in the conceptual design stage. The tool is based on the theory of morphological indicators: the volume indicator, displacement indicator, buckling indicator and first natural frequency indicator. These allow a designer to determine the most material efficient Warren or Howe truss bridge design with user-defined constraints concerning deflection, load frequency, buckling and overall dimension. Subsequently, the tool was tested and compared to calculations made in the finite element modelling software Diamonds. In total, 72 steel bridge structures were tested. From these it could be concluded that the manual calculations in Diamonds in general confirmed the results obtained with the automated design tool based on morphological indicators. As such, it allows a designer to converge more quickly towards the best performing structure, thus saving time, materials, and corresponding costs and energy.

Reclaimed asphalt pavement (RAP) is a recyclable aggregate produced during the demolition of old flexible pavements and consists of natural aggregates (NA) coated with aged bitumen. The detrimental effect caused by the bitumen coating on strength and porosity has limited the use of RAP on traditional cementitious systems. This study investigates the potential use of fine RAP to substitute NA in the production of alkali-activated slag mortars (AAM). The effect of different activator dosages was assessed, i.e., either 4% or 6% Na2O (wt. slag) combined with a modulus of silica equal to 0, 0.5 and 1.0. The characterisation of 100% RAP-AAM consisted of hydration kinetics (Isothermal Calorimetry), pore size distribution (Mercury Intrusion Porosimetry), mechanical performance (Compressive and Flexural strength), and microstructure analysis (Scanning Electron Microscopy and Confocal Laser Scanning Microscopy). The results show that RAP aggregates do not compromise the reaction of the matrices; however, it causes a significant strength loss (compressive strength of RAP-mortars 54% lower than reference NA-mortar at 28 days). The higher porosity at the interface transition zone of RAP-AAM is the main responsible for the lower strength performance. Increasing silicate dosages improves alkaline activation, but it has little impact on the adhesion between aggregate and bitumen. Despite the poorer mechanical performance, 100% RAP-AAM still yields enough strength to promote this recycled material in engineering applications.

Roads are exposed to solar radiation for the entire duration of their service life; depending on the season, the intensity and level of exposure can vary for different locations leading to differences in the magnitude of the damage. In Australia, many local road authorities have already started understanding that their roads are deteriorating faster due to non-load related effects (i.e., environmental damage). The present paper discusses the damage caused by UV radiation on bituminous binders and explores the protecting effect provided by the use of end-of-life tires in the form of crumb rubber. The results suggest that adding crumb rubber to bituminous binders has the potential to significantly reduce the non-load related environmental damage caused by the UV radiation of the Sun.

The construction industry is responsible for half of the currently excavated amount of raw materials. In addition, a quarter of all waste in the European Union is construction waste. This construction waste comprises numerous materials that can still be reused or recycled. Thus, a shift to a circular construction sector is necessary. To make this shift, it is vital to enable the measurement of and the progress toward circularity. Therefore, this paper investigates the currently available circularity indicators with regard to the 4 Rs—Reduce, Reuse, Recycle, Recover. Subsequently, a comprehensive Circular Construction Indicator framework is introduced that evaluates a construction project according to the three typical construction phases: design, construction, and end-of-life. In this, new partial indicators to assess material scarcity, structural efficiency, and service life prediction should help designers consider these aspects already in the conceptual design stage. Lastly, suggestions for further research are defined to develop further said new partial indicators.

It is well documented that most bituminous binders contain crystallisable material. This crystallisable fraction, often referred to as paraffinic or natural wax, is associated with the bitumen’s origin and has an influence on its rheological performance. In the literature, Differential Scanning Calorimetry (DSC) is the primary technique used to determine the melting and crystallisation behaviour of this waxy fraction. However, in bitumen, thermal transitions in DSC are typically very broad and can be combined with recrystallisation effects upon reheating. This work explores the potential crystallisation and melting process of a waxy and a wax-free bitumen via three different approaches: DSC, Wide-Angle X-ray Diffraction (WAXD) and Confocal Laser Scanning Microscopy (CLSM). The findings reveal that the DSC transitions of the waxy bitumen are in good agreement with the corresponding occurrence of WAXD signals and to some extent with the formation and disappearance of the surface microstructures which were followed at two cooling and heating rates. WAXD results additionally demonstrate that the crystalline material in bitumen is organised in an orthorhombic unit cell, typical for straight chain aliphatic structures. On the other hand, DSC and WAXD support the lack of crystallinity for the wax-free bitumen which could explain its featureless CLSM surface. Overall, the originality of this work resides in the disclosure of connections between crystallographic properties, thermal transitions and the surface micromorphology of bitumen.

This state-of-the-art review was aimed to conduct a comprehensive literature survey to summarize experiences of crumb rubber (CR) application in concrete within the last 30 years. It shows that certain gaps prevent obtaining a coherent overview of both mechanical behaviour and environmental impact of crumb rubber concrete (CRC) to object to the stereotypes which prevent to use of CR in concrete in the construction industry. Currently, four major barriers can be distinguished for a successful CR application in the concrete industry: (1) the cost of CR recycling, (2) mechanical properties reduction, (3) insufficient research about leaching criteria and ecotoxicological risks and (4) recyclability of CRC. The application of CR in concrete has certainly its advantages and in general cannot be ignored by the construction industry. CR can be applied, for example, as an alternative material to replace natural aggregates and CRC can be used as recycled concrete aggregates (RCA) in the future. A certain diversity for the CR application can be introduced in a more efficient way when surface treatment and concrete mix design optimization are properly developed for each type of CR application in concrete for possible field applications. The role of CRC should not be limited to structures that are less dependent on strength.

Shape from focus is an accurate, but relatively time-consuming, 3D profilometry technique (compared to e.g., laser triangulation or fringe projection). This is the case because a large amount of data that needs to be captured and processed to obtain 3D measurements. In this paper, we propose a two-step shape-from-focus measurement approach that can improve the speed with 40%. By using a faster profilometry technique to create a coarse measurement of an unknown target, this coarse measurement can be used to limit the data capture to only the required frames. This method can significantly improve the measurement and processing speed. The method was tested on a 40 mm by 40 mm custom target and resulted in an overall 46% reduction of measurement time. The accuracy of the proposed method was compared against the conventional shape from focus method by comparing both methods with a more accurate reference.

Transparent binder is used to substitute conventional black asphalt binder and to provide light-colored pavements, whereas nano-TiO2 has the potential to promote photocatalytic and self-cleaning properties. Together, these materials provide multifunction effects and benefits when the pavement is submitted to high solar irradiation. This paper analyzes the physicochemical and rheological properties of a transparent binder modified with 0.5%, 3.0%, 6.0%, and 10.0% nano-TiO2 and compares it to the transparent base binder and conventional and polymer modified binders (PMB) without nano-TiO2. Their penetration, softening point, dynamic viscosity, master curve, black diagram, Linear Amplitude Sweep (LAS), Multiple Stress Creep Recovery (MSCR), and Fourier Transform Infrared Spectroscopy (FTIR) were obtained. The transparent binders (base and modified) seem to be workable considering their viscosity, and exhibited values between the conventional binder and PMB with respect to rutting resistance, penetration, and softening point. They showed similar behavior to the PMB, demonstrating signs of polymer modification. The addition of TiO2 seemed to reduce fatigue life, except for the 0.5% content. Nevertheless, its addition in high contents increased the rutting resistance. The TiO2 modification seems to have little effect on the chemical functional indices. The best percentage of TiO2 was 0.5%, with respect to fatigue, and 10.0% with respect to permanent deformation.

The fatigue performance and healing ability of asphalt pavements are important for mixture design, rehabilitation, and maintenance of the roads. By analyzing these parameters in an asphalt mixture, it is possible to predict the crack formation and propagation in asphalt pavements and healing of these cracks during the rest periods. The healing effect in asphalt mixtures has been observed and verified by many researchers and different methods exist to evaluate this phenomenon. However, current methods are still inadequate to fully observe and quantify the healing phenomenon in asphalt mixtures. In this study, a digital image correlation (DIC) method is used to calculate the strain map on the surface of cylindrical asphalt specimens during the indirect tensile fatigue test. This strain map is used to detect the location of crack initiations and development of the microcracks during the experiments. Next, the specimens are unloaded and the temperature of the climate chamber is increased to 60 °C for 18 h to investigate the healing phenomenon on the surface of the specimens. It is observed that the strain reduces near the microcrack areas especially at the tip of the microcracks. Furthermore, using DIC it is possible to observe the healing rate and the minimum time required to heal the microcracks on the surface of the specimens.

In this study, the feasibility of a natural peat fiber and finely ground peat powder as a modifier for bitumen was investigated. Initially, the as-received peat material was characterized in detail: the material was ground to various degrees, separated into fiber and powder fractions, and the gradation of the powder fraction as well as the size of the fibers were determined. A possible solubility in bitumen, the moisture content, and the density of both fractions were evaluated, and a limited chemical characterization of the fibers was conducted. Secondly, the rheological behavior of the powder and the fibers when blended with bitumen was evaluated. Additionally, a limited asphalt study was conducted. The rheological data showed the stiffening effects of the powder fraction and the presence of a fiber network, which were obvious as a plateau modulus towards lower frequencies. The fiber network was strain-dependent and showed elastic effects. This was further confirmed by the multiple stress creep recovery (MSCRT) tests. These tests also indicated that the fibers should improve the rutting resistance, although it was not possible to confirm this in asphalt rutting tests. Asphalt drainage tests demonstrated that adding dry peat, whether this is ground or not, is effective in reducing the binder drainage. However, the data also revealed that the amount of added peat fibers and powder should be limited to avoid difficulties in the compaction of these asphalt mixes.

In his late writings Husserl emphasizes how the semiotic properties of writing, and of mathematical formulae and diagrams, are crucial for the historical, cross-generational survivability of meaning and specifically indispensable to the operation of scientific knowledge. However, the demand for objectivity, exactitude, and repeatability insidiously interferes with the meaning that such signs seek to express. This leads to a duality of objectivity encapsulated in the notion “the sedimentation of meaning”. On this view, the transmission of objectivity established in an original sense-constituting act cannot survive unless being deposited in some external form, which at the same time risks the original sense being irrevocably lost in a web of signification that amounts to nothing more than empty and meaningless symbol manipulation. I discuss Husserl’s analysis and propose that it is limited by its one-sided focus on the negative impact of modernity. I compare Husserl’s account with Heidegger’s even more radical critique of modern society as one where a so-called “technological” mode of “revealing” reigns supreme at the expense of eradicating other, and more authentic ways to apprehend the world. I critically reconstruct the respective position of both thinkers and show how they point not only to a criticism of the instrumentalization and formalization of knowledge in modern society, but that they are just as importantly highlighting essential semiotic properties of signs.

Oral leukoplakia (OL) is a potentially malignant oral disorder. The Gold Standard treatment is to remove surgically the OL. Despite optimal surgery, the recurrence rates are estimated to be 30%. The reason for this is unknown. The aim of this study was to investigate the clinical factors that correlate with recurrence after surgical removal of OL. In a prospective study data were collected from 226 patients with OL. Forty-six patients were excluded due to incomplete records or concomitant presence of other oral mucosal diseases. Overall, 180 patients proceeded to analysis (94 women and 86 men; mean age, 62 years; age range, 28-92 years). Clinical data, such as gender, diagnosis (homogeneous/non-homogeneous leukoplakia), location, size, tobacco and alcohol use, verified histopathological diagnosis, and clinical photograph, were obtained. In patients who were eligible for surgery, the OL was surgically removed with a margin. To establish recurrence, a healthy mucosa between the surgery and recurrence had to be confirmed in the records or clinical photographs. Statistical analysis was performed with the level of significance set at P