CivilEng, Volume 2, Issue 2 (June 2021) – 15 articles

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components. Full article

Concrete splitting failure due to tension load can occur when fastening systems are located close to an edge or corner of a concrete member, especially in thin members. This failure mode has not been extensively investigated for anchor channels. Given the current trend in the construction industry towards more slender concrete members, this failure mode will become more and more relevant. In addition, significantly different design rules in the United States and Europe indicate the need for harmonization between codes. Therefore, an extensive numerical parametric study was carried out to evaluate the influence of member thickness, edge distance, and anchor spacing on the capacity of anchor channels in uncracked and unreinforced concrete members. One of the main findings was that the characteristic edge distance depends on the member thickness and can be larger than 3h_ef (h_ef = embedment depth) for thin members. Based on the numerical and experimental test results, modifications of the design recommendations for the splitting failure mode are proposed. Overall, the authors recommend performing the splitting verification separately from the concrete breakout to design anchor channels in thin members more accurately. Full article

Heavy duty riveted gratings are a good alternative for applications that often employ other deck systems, if they are carefully analyzed under static and fatigue loads. Understanding the static behavior of a riveted steel deck under tire patch loads will aid in establishing a design model based on an effective beam width. In addition, use of a riveted system avoids welded details that may lead to fatigue cracking, thereby improving design life. In this study, analysis of a typical riveted steel deck under a standard AASHTO fatigue truck with a 15% impact factor was conducted. Hand calculations were compared with the results of a finite element model using SAP2000 v19.2.1. Bending moments and stresses were evaluated and compared. Stresses at the rivet hole for the most highly loaded bearing bar were evaluated. A model for fatigue cracking around a rivet hole is discussed. Full article

Economic and social development of urban and rural areas continues in parallel with the increase of the human population, especially in developing countries, which leads to sustained expansion of impervious surface areas, particularly paved surfaces. The conversion of pervious surfaces to impervious surfaces significantly modifies local energy balance in urban areas and contributes to urban heat island (UHI) formation, mainly in densely developed cities. This paper represents a literature review on the causes and consequences of the UHI and potential measures that could be adopted to improve the urban microclimate. The primary focus is to discuss and summarise significant findings on the UHI phenomenon and its consequences, such as the impact on human thermal comfort and health, energy consumption, air pollution, and surface water quality deterioration. Regarding the measures to mitigate UHI, particular emphasis is given to the reflective and permeable pavements. Full article

Experimental testing of deformed rebar anchors (DRAs) has not been performed extensively, so there is limited test data to understand their failure behavior. This study aims to expand upon these limited tests and understand the behavior of these anchors, when loaded in tension. Analytical benchmark models were created using available test data and a parametric study of deformed rebar anchors was performed. Anchor diameter, spacing, embedment, and number of anchors were varied for a total of 49 concrete breakout simulations. The different failure modes of anchors were predicted analytically, which showed that concrete breakout failure is prominent in the DRA groups. The predicted concrete breakout values were consistent with mean and 5% fractile concrete capacities determined from the ACI concrete capacity design (CCD) method. The 5% fractile factor determined empirically from the simulation results was k_c = 26. This value corresponds closely with k_c = 24 specified in ACI 318-19 and ACI 349-13 for cast-in place anchors. The analysis results show that the ACI CCD formula can be conservatively used to design DRAs loaded in tension by applying a k_c factor no greater than 26. Full article

Natural hydraulic lime-based grouts are often used in the structural consolidation of old stone masonry walls, mainly to re-establish the monolithic behaviour of masonry constructions. To ensure an adequate grouting operation, it is essential to have good fresh and hardened grout properties. The motivation of the present study was to examine the fresh and hardened properties of natural hydraulic lime grouts with nano-silica (NS) and silica fume (SF). The contribution of these materials and the dosage of a high range water reducer admixture (HRWR) were investigated on the rheological properties, water capillarity, open porosity and mechanical strength of injection grouts. The effects on rheology were analysed through plastic viscosity and yield stress. The results indicated that, even for reduced NS content, an increase in plastic viscosity and yield stress occurred, which required a higher HRWR content in order to not compromise the grout’s rheological performance. The results also showed that, when NS and SF were combined, a beneficial joint effect occurred, resulting in a substantial and positive change on the mechanical strength and microstructure of the hardened injection grouts. Taguchi’s method was used to optimize the grout’s formulation and to fulfil the required performance concerning the fresh and hardened state. Full article

During earthquakes, buildings are subjected to loads well beyond their usual demands, resulting in high stresses in the structural components and additional inertial forces coming from the non-structural elements. When post-installed anchors are used to form the connection between non-structural or structural members and the primary reinforced concrete structure, these anchors are also subjected to high seismic demands. To determine whether a post-installed anchor is suitable for such applications, it is assessed for its performance under seismic demands. In this review paper, the current European approach for testing and qualification of post-installed anchors under seismic actions is reviewed and discussed in the context of structural applications where anchors are used to form the connection between structural members that participate in the load-transfer mechanism against seismic loads. The first part of this paper provides a description of the testing procedures and the criteria against which the anchor performance is assessed. The procedures and assessment criteria are discussed regarding the suitability in the case of the above-described structural applications. In the second part, the qualification of anchors under seismic actions is discussed in the light of an upcoming performance-based design approach for anchors. In such an approach, information on the displacement and hysteretic behavior of an anchor in a broader range of the load–displacement curve is of vital importance. Therefore, additional testing approaches might be required in order to supplement the information on anchor performance provided in the current testing procedures. One such testing approach for pulsating tension load is reported. Full article

The non-destructive ultrasound technique is an easy and inexpensive technique widely used in industry to evaluate the properties of engineering materials. Despite its popularity in industrial applications, such as evaluating steel materials, the ultrasound technique has not been thoroughly investigated for the purpose of characterizing asphalt materials in general, nor specifically determining the asphalt binder content of asphalt mixtures. The purpose of this study was to explore the feasibility of utilizing measurements based on the non-destructive ultrasound technique to detect changes in the asphalt binder content in asphaltic mixture specimens. Two performance-grade binders, PG64-28 and PG76-22, and two rubber-modified binders were selected. The rubber-modified binders were produced by adding crumb rubber to the two performance-grade binders, PG64-28 and PG76-22, and were designated as PG64-28R and PG76-22R. The amount of crumb rubber added to these rubber-modified binders was 15% by weight of the PG64-28 and PG76-22 binders. The aggregate gradations for all of the asphalt mixtures were the same. The asphalt mixture specimens were used to obtain measurements for: (1) the ultrasound wave speed through the specimens; and (2) and the integrated response (IR) of the specimens. The results indicated that, generally, the ultrasound wave speed decreases with an increase in binder content. This is expected due to the binder’s attenuation and slowing effect on the wave speed. The results also indicated that, generally, the integrated response (IR) decreases with an increase in binder content. This can be explained by the fact that the increased binder content in asphalt mixture specimens increases their tendency to absorb more energy. Full article

During the last decades, different technologies to anchor steel elements in concrete were proposed. The present work presents the results of a preliminary investigation of a new connection characterized by single steel plates that are directly bonded on concrete surfaces. The anchor response was experimentally investigated under both tension and shear actions. Specific conditions influencing the behavior of the bonded assembly were discussed, with particular reference to the presence of cracks and crack cycling in concrete. Full article

Asphalt aging is one of the main factors causing asphalt pavements deterioration. Previous studies reported on some aging benefits of asphalt rubber mixtures through laboratory evaluation. A field observation of various pavement sections of crumb rubber modified asphalt friction courses (ARFC) in the Phoenix, Arizona area indicated an interesting pattern of transverse/reflective cracking. These ARFC courses were placed several years ago on existing jointed plain concrete pavements for highway noise mitigation. Over the years, the shoulders had very noticeable and extensive cracking over the joints; however, the driving lanes of the pavement showed less cracking formation in severity and extent. The issue with this phenomenon is that widely adopted theories that stem from continuum mechanics of materials and layered mechanics of pavement systems cannot directly explain this phenomenon. One hypothesis could be that traffic loads continually manipulate the pavement over time, which causes some maltenes (oils and resins) compounds absorbed in the crumb rubber particles to migrate out leading to rejuvenation of the mastic in the asphalt mixture. To investigate the validity of such a hypothesis, an experimental laboratory testing was undertaken to condition samples with and without dynamic loads at high temperatures. This was followed by creep compliance and indirect tensile strength testing. The results showed the higher creep for samples aged with dynamic loading compared to those aged without loading. Higher creep compliance was attributed to higher flexibility of samples due to the rejuvenation of the maltenes. This was also supported by the higher fracture energy results obtained for samples conditioned with dynamic loading from indirect tensile strength testing. Full article

Beam-column-joints (BCJ) in reinforced concrete (RC) frames are known to be critical against seismic actions. Hence, several researchers have conducted related investigations. The loading history used in the experimental investigations must be a sufficiently accurate and conservative representation of seismic loading on the structure and should trigger all possible critical failure mechanisms in the subassembly. Presently, there is significant diversity in the loading histories used for seismic investigation of structural subassemblies. This paper intends to propose an optimum loading history for considering bidirectional (horizontal) seismic action on 3D-RC BCJ subassemblies. To this end, the available loading histories (unidirectional and bidirectional) for simulation of seismic loads on RC joint subassemblies are reviewed in the context of the demands they impose on the joints. Finite element modeling and analyses are used as a tool for investigating the response of 3D-BCJ subassembly under different bidirectional loading states. Full article

This study presents an investigation into the extent to which emerging building information modelling (BIM) can be applied to construction logistics management (CLM). Given the specialist nature of the domains, the study employed an in-depth qualitative interview, whereby six experts were interrogated about their experiences of BIM for CLM. The study found the main applications of BIM on CLM to be the creation of three-dimensional (3D) site layout plans and four-dimensional (4D) coordination of site processes and common user plant, updating the 4D logistics plan as the project progressed and collaboration in BIM-based logistics coordination. Furthermore, there was a consensus amongst interviewees on improvement in site safety, comprehension of logistics information, efficiency on site, and effectiveness of layout planning as the main benefits. Lastly, the lack of training with implications on understanding was one of the main barriers to applying BIM to CLM. The findings from this study have the potential to stimulate the uptake of BIM by construction logistics practitioners. By so doing, the performance construction project delivery can be improved, and waste can be minimised or eliminated. Full article

Construction site utilization planning (CSUP), also known as jobsite layout planning, has implications on the safety, productivity, scheduling, and budgetary performance of a project. Past research efforts on CSUP have mainly focused on the development of optimization systems that delineate and allocate site space to predetermined temporary facilities based on time and/or cost constraints. Despite the significant body of knowledge on site optimization systems, the applicability of optimization algorithms remains limited due to the unique requirements and site constraints faced on each construction project. An important aspect not identified in past research efforts are the current practices for site utilization plan (SUP) development currently used by the construction industry. Therefore, the objectives of this research were to: (1) determine the state-of-the-practice regarding CSUP within the construction industry, (2) identify current SUP best practices, and (3) develop a procedure that outlines the CSUP process. An electronic survey was sent to 4021 industry professionals inquiring on current CSUP practices. A total of 240 responses were received, for a response rate of 6%. Thirteen best practices were identified from the survey, each focusing on an important aspect of the site planning process. These best practices were validated through a follow-up survey, as well as in-person interviews with experienced construction professionals. From the best practices, a procedure describing the development of a SUP was created. Key components identified were: (1) begin CSUP during budget development, (2) involve all stake holders associated with the project, and (3) remain flexible on space allocation throughout the construction life cycle. Full article

This article proposes a simplified method for determining the elastic radius ratio of the multi-storey reinforced concrete building. The elastic radius ratio is the benchmark parameter of the buildings in determining torsional stability during an earthquake. When buildings are torsionally flexible, the torsional component of seismic response amplifies the overall response of the building. Because of the numbers of simplified assumptions such as the adoption of the single-storey model, much of the published articles have a very limited range of application. Quantifying the interaction of different forces in multi-story non-proportional buildings has been the main challenge of these studies. The proposed “shear and bending combination method” solves this by introducing parameters that can determine the relative influence of individual actions. Moreover, the proposed method applies to buildings with all type of structural systems, having asymmetry, and accidental eccentricity. The method is validated through a parametric study consisting of eighty-one building models and using computer analysis. The proposed method and the research findings of this study are useful in determining the torsional stability of the building, in verifying the results of the computer-based analysis, and in optimizing the structural system in the buildings. Full article

A considerable part of Southern European countries building stock was constructed before the implementation of national thermal regulations, and as such, it is currently exposed to challenges such as energy poverty and climate change. Portuguese public social housing presents a significant variety of construction systems and applied typologies. Among them, the “Novobra NK1”, a precast concrete construction system that exploits some innovative features in envelope components, has been used in several projects. Considering the importance of retrofitting to improve and adapt the thermal behaviors of buildings to face the aforementioned challenges, this article aims to provide an understanding of the behavior of a NK1 thermal envelope of a dwelling located in Covilhã, Portugal, and the impact of some constructive envelope retrofit measures applied. Results show that existing opaque envelope elements and glazed areas present characteristics that are no longer able to provide proper responses to contemporary building constructive requirements. External insulation was identified as a key retrofit measure, window replacement also being an advised solution for rigorous heating seasons. Improvements from the internal side of windows, such as roller shades, may provide few benefits during cooling seasons, and applying solar films is not advised without a proper thermal repercussion analysis. Full article