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Buildings, Volume 9, Issue 2 (February 2019)

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Cover Story (view full-size image) The aim of the research is to explore the possibilities of using infrared thermography in detecting [...] Read more.
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Open AccessArticle Numerical Simulation of the Semi-Rigid Behaviour of Integrally Attached Timber Folded Surface Structures
Received: 18 January 2019 / Revised: 8 February 2019 / Accepted: 18 February 2019 / Published: 25 February 2019
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Abstract
Timber folded surface structures assembled using semi-rigid multiple tab and slot joints (MTSJ) have been shown to form feasible structural systems with high load bearing potential. However, for their further development and use on large building scales, a pertinent model for prediction of [...] Read more.
Timber folded surface structures assembled using semi-rigid multiple tab and slot joints (MTSJ) have been shown to form feasible structural systems with high load bearing potential. However, for their further development and use on large building scales, a pertinent model for prediction of their structural behaviour has yet to be developed. This paper focuses on simplified numerical methods for accurately modelling the semi-rigid structural behaviour of bidirectional timber folded surface structures with multiple tab and slot connections. Within this scope, the structure behaviour is considered to be in the elastic stage. Three practical methods of analysis for such structural systems are presented. The first two approaches use the Finite Element Method (FEM), where the theory of plates and shells are applied. In the first method, the MTSJs are modeled using strip element models, while, in the second strategy, spring models are used. The third modeling strategy elaborates on the new macroscopic mechanical models, referred to as macro models. Sets of one-dimensional (1D) elements are used to represent the mechanical behaviour of the entire system. Both linear and geometric nonlinear analysis are performed for all three modeling strategies. The numerical results are then validated against the large scale experiments. Comparison of the strip and spring element model results have shown that the strips represent more accurately the experimentally obtained values. Concerning the macro modelling approach, very good agreement with both detailed FE modelling approaches, as well as experimental results, were obtained. The results indicate that both linear and nonlinear analysis can be used for modelling the displacements within the elastic range. However, it is essential to include geometric nonlinearities in the analysis for accurate modelling of occurring strains as well as for displacements when considering higher load levels. Finally, it is demonstrated that including semi-rigidity in the numerical models is of high importance for analysing the behaviour of timber folded surface structures with MTSJ. Full article
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Open AccessFeature PaperArticle Understanding the Office: Using Ecological Momentary Assessment to Measure Activities, Posture, Social Interactions, Mood, and Work Performance at the Workplace
Received: 30 January 2019 / Revised: 15 February 2019 / Accepted: 19 February 2019 / Published: 25 February 2019
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Abstract
Studying the workplace often involves using observational, self-report recall, or focus group tools, which all have their established advantages and disadvantages. There is, however, a need for a readily available, low-invasive method that can provide longitudinal, repeated, and concurrent in-the-moment information to understand [...] Read more.
Studying the workplace often involves using observational, self-report recall, or focus group tools, which all have their established advantages and disadvantages. There is, however, a need for a readily available, low-invasive method that can provide longitudinal, repeated, and concurrent in-the-moment information to understand the workplace well. In this study, ecological momentary assessment (EMA) was used to collect 508 real-time responses about activities, posture, work performance, social interactions, and mood in 64 adult office workers in three Australian workplaces. The response rate was 53%, and the time to fill out the survey was 50 seconds on average. On average, the participants were sitting, standing, and walking in 84%, 9%, and 7% of survey instances, respectively. The participants reported they were working alone at their desks in 55% of all reported instances. Reported mood varied up to nine points within one person over the course of the post-occupancy observations. EMA can be used to paint a rich picture of occupants’ experiences and perceptions and to gain invaluable understanding of temporal patterns of the workplace, how the space is used, and how aspects of the workplace interact. This information can be used to make improvements to the physical and social workspaces and enhance occupants’ work performance and mood. Full article
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Open AccessReview Multiple-Layer Microperforated Panels as Sound Absorbers in Buildings: A Review
Received: 22 January 2019 / Revised: 6 February 2019 / Accepted: 15 February 2019 / Published: 25 February 2019
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Abstract
Sound absorbing materials are used in buildings to dissipate sound energy into heat using viscous and thermal processes. Sound absorbers increase the transmission loss of walls, decrease the reverberation time of rooms, and attenuate the noise generated by internal sound sources. Porous absorbers [...] Read more.
Sound absorbing materials are used in buildings to dissipate sound energy into heat using viscous and thermal processes. Sound absorbers increase the transmission loss of walls, decrease the reverberation time of rooms, and attenuate the noise generated by internal sound sources. Porous absorbers (fibrous, cellular, or granular) are the most used materials in noise control applications because of their high performance-to-cost ratio in the frequency band of interest. However, when cleaning conditions and health reasons are of concern, microperforated panel (MPP) absorbers may be the preferred choice. MPPs, consisting of many minute (sub-millimetric) holes in a panel, are tunable absorbers in a prescribed frequency band, whose main shortcomings are high manufacturing cost and limited absorption frequency band. Currently, the production cost of MPPs can be drastically reduced by means of modern techniques. The absorption frequency band can be considerably enlarged by designing multiple-layer MPPs (ML-MPPs). The aim of this article is to review the high potential of ML-MPPs as a modern, clean, and healthy alternative to porous materials for sound absorption. Full article
(This article belongs to the Special Issue Noise Control in Buildings)
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Open AccessArticle Metaphors as Discourse Interaction Devices in Architectural Design
Received: 24 January 2019 / Revised: 16 February 2019 / Accepted: 19 February 2019 / Published: 22 February 2019
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Abstract
Metaphor is a fundamental heuristic supporting cognitive and communicative requirements in design problem solving. This reasoning mechanism helps structure how architects reason about problems, and how they approach design situations from novel perspectives. This paper investigated empirically the use of metaphors during the [...] Read more.
Metaphor is a fundamental heuristic supporting cognitive and communicative requirements in design problem solving. This reasoning mechanism helps structure how architects reason about problems, and how they approach design situations from novel perspectives. This paper investigated empirically the use of metaphors during the conceptual front edge design, known as the most creative stage of the process. Figurative phenomena were analyzed in their original context of occurrence. Emerging metaphorical expressions generated during communication interactions maintained by sixty architects were identified and examined based on protocol analysis approach. Metaphors were further categorized according to main experiential domains at different levels of detail, as well as in terms of image and conceptual descriptions. The study contributed to gain a deeper insight into the rhetorical potential of metaphor during design problem solving, and to strengthen its centrality in architecture. Full article
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Open AccessArticle Thermal Performance of Hollow-Core Slab Ventilation System with Macro-Encapsulated Phase-Change Materials in Supply Air Duct
Received: 8 January 2019 / Revised: 9 February 2019 / Accepted: 18 February 2019 / Published: 22 February 2019
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Abstract
The aim of this research was to evaluate the effectiveness of phase-change materials (PCMs) incorporated into the supply air duct of a hollow-core slab ventilation system. Both experimental and numerical approaches were adopted in this investigation. In the experimental work, the air was [...] Read more.
The aim of this research was to evaluate the effectiveness of phase-change materials (PCMs) incorporated into the supply air duct of a hollow-core slab ventilation system. Both experimental and numerical approaches were adopted in this investigation. In the experimental work, the air was passed through a PCM-incorporated aluminum air duct, and the temperature at various points of the duct was recorded. Computational fluid dynamics models of the PCM-incorporated supply air duct and the hollow-core slab were developed and validated with the respective experimental data. The validated models were used to simulate the performance of PCM-incorporated hollow-core slabs during summer in Melbourne, Australia. The results showed that the reduction in temperature fluctuation varied with the way the PCM was incorporated inside the supply air duct. The temperature difference was maximum and was maintained for a longer period when the PCM was spread to all four internal surfaces of the supply air duct. The results also showed that the effectiveness of the combined PCM–air duct–hollow-core slab system in reducing the temperature fluctuation was lower than the individual performance of the PCM–air duct and hollow-core concrete slab for a given inlet temperature condition during the simulated period. This was because the integration of PCMs in the supply air duct resulted in a precooling effect which reduced the difference between the amplitude of slab inlet temperature swing and average slab temperature. As a result, the reduction in temperature fluctuation due to the thermal mass of the hollow-core slab was 21% lower in the presence of PCMs compared to the no-PCM case. Full article
(This article belongs to the Special Issue Phase Change Materials of Buildings)
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Open AccessArticle Rheological and Strength Behavior of Binary Blended SCC Replacing Partial Fine Aggregate with Plastic E-Waste as High Impact Polystyrene
Received: 31 December 2018 / Revised: 13 February 2019 / Accepted: 15 February 2019 / Published: 22 February 2019
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Abstract
Disposing electronic plastic waste into construction materials is an eco-friendly and energy efficient solution to protect the environment. This work is aimed at enhancing the strength of self-compacting concrete (SCC) replacing sand with electronic waste, namely, High Impact polystyrene (HIPS) plastic granules and [...] Read more.
Disposing electronic plastic waste into construction materials is an eco-friendly and energy efficient solution to protect the environment. This work is aimed at enhancing the strength of self-compacting concrete (SCC) replacing sand with electronic waste, namely, High Impact polystyrene (HIPS) plastic granules and cementitious material with fly ash. SCC is designed with the optimized binder content of 497 kg/m3 using Fly Ash (30% by weight of cement) and 0.36 as water-to-binder ratio for all the mixtures. High Impact Polystyrene granules are replaced with sand up to 40% (by volume) at a regular interval of 10%. Rheological behavior is observed with the slump flow test for slump diameter, V-funnel test for flow time, and the L-box test for heights ratio, respectively. Strength behavior is studied by performing split tensile strength, and compressive strength tests after a period of 7, 28, and 90 days, respectively. Both fly ash and HIPS aggregate in addition to SCC up to 30% exhibits a minimal strength reduction with a promising performance in workability. Hence incorporation of both fly ash and HIPS granules up to 30% in SCC is a viable eco-friendly technique, with the beneficial economic impact on the construction industry. Full article
(This article belongs to the Special Issue Green Building Materials)
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Open AccessArticle Thermal Performance of Insulated Constructions—Experimental Studies
Received: 18 January 2019 / Revised: 11 February 2019 / Accepted: 15 February 2019 / Published: 21 February 2019
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Buildings that are designed to meet high-energy performance requirements, e.g., passive houses, require well-insulated building envelopes, with increased insulation thicknesses for roof, wall and floor structures. We investigate whether there are differences in the efficiency of thermal insulation materials at different moisture levels [...] Read more.
Buildings that are designed to meet high-energy performance requirements, e.g., passive houses, require well-insulated building envelopes, with increased insulation thicknesses for roof, wall and floor structures. We investigate whether there are differences in the efficiency of thermal insulation materials at different moisture levels in the insulation and if there is a larger or smaller risk of natural convection in wood-fibre based insulation than in mineral wool. The work has mainly been performed by use of laboratory measurements included permeability properties and full-scale measurements of thermal transmittance of mineral wool and wood-fibre insulated constructions. In addition, calculations have been used to calculate resulting effects on the thermal performance of constructions. Results showed that the thermal conductivity was unaffected by moisture in the hygroscopic range. The air permeability was found to be approximately 50% higher for the wood-fibre insulation compared to mineral wool insulation. Measurements showed that the largest U-values and Nusselt numbers were found for the wall configuration. Calculation of the U-value of walls showed that in order to achieve the same U-value for the wood-fibre insulated wall as the mineral wool, it is necessary to add 20 mm insulation to the 250 mm wall and approximately 30 mm for the 400 mm wall. Full article
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Open AccessArticle Retrofitting of Imperfect Halved Dovetail Carpentry Joints for Increased Seismic Resistance
Received: 27 December 2018 / Revised: 5 February 2019 / Accepted: 13 February 2019 / Published: 18 February 2019
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Abstract
This paper presents possibilities for anti-seismic improvement of traditional timber carpentry joints. It is known that the structural response of historical roof frameworks is highly dependent on the behavior of their joints, particularly, their capacity for rotation and energy dissipation. Any strengthening, or [...] Read more.
This paper presents possibilities for anti-seismic improvement of traditional timber carpentry joints. It is known that the structural response of historical roof frameworks is highly dependent on the behavior of their joints, particularly, their capacity for rotation and energy dissipation. Any strengthening, or retrofitting, approach must take into account conservation requirements, usually expressed as conditions involving minimal intervention. Several retrofitting methods were tested on replicas of historical halved joints within various national and international research projects. The joints were produced with traditional hand tools, and made using aged material taken from a demolished building. The paper presents two approaches, each utilizing different retrofitting technologies that avoid completely dismantling the joint and consequently conserve frame integrity. The energy dissipation capacity is increased by inserting mild steel nails around a wooden pin, and connecting the two parts of the halved joint. In the second case, two thin plates made of a material with a high friction coefficient are inserted into the joint and fastened to the wooden elements. This is done by removing the wooden connecting pin and slightly opening a slot for the plates between the halved parts. In addition, the paper presents an application for disc brake plates, as well as thin plates made of oak. Full article
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Open AccessArticle Critical Success Factors (CSFs) for e-Procurement Adoption in the Nigerian Construction Industry
Received: 5 November 2018 / Revised: 10 December 2018 / Accepted: 11 December 2018 / Published: 18 February 2019
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Previous research works on the integration of e-Procurement technologies in the construction process in Nigeria showed that it has been slow and low. However, there are few empirical studies on the duration for which it has permeated the construction industry, the actual proponents [...] Read more.
Previous research works on the integration of e-Procurement technologies in the construction process in Nigeria showed that it has been slow and low. However, there are few empirical studies on the duration for which it has permeated the construction industry, the actual proponents and the metrics that can engender successful integration of e-Procurement technologies, applications, and tools in the construction procurement process, especially in a developing country like Nigeria. The study was aimed at evaluating the critical success factors (CSFs) for e-Procurement adoption in the Nigerian construction industry. The study was carried out in the six geo-political zones in Nigeria using a survey research design. Construction stakeholders were selected using purposive and random sampling techniques. A total of 1092 questionnaires were retrieved in this study, but the data of 759 actual users of e-Procurement systems were analyzed in this study using descriptive statistics and principal component analysis (PCA). An assessment of the duration users have been participating in the e-Procurement environment revealed that most Quantity Surveyors have been exposed to the use of e-Procurement technologies for over 10 years. A large proportion of the construction stakeholders picked up the use of the technology within the last 5 years. Further analysis showed that contracting firms have the largest participation in the use of e-Procurement systems. The study also revealed that construction stakeholders perceived the availability of reliable, affordable, and fast Internet services as the most critical success factor for the adoption of e-Procurement technologies. The critical success factors (CSFs) were further classified into management support for physical infrastructure, and human factors and characteristics of the technology. The study showed that these critical success factors (CSFs) are crucial for the adoption of e-Procurement systems in the Nigerian construction industry. The study recommended that there is still a need for increased awareness of the e-Procurement tools and technologies and the benefits that are accrued from their use among public sector construction participants. This will in turn influence the provision of the required information and communication technology (ICT) physical infrastructure and formulation of appropriate policies and standards for successful e-Procurement integration in the Nigerian construction industry. Full article
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Open AccessArticle Responsive Parametric Building Free Forms Determined by Their Elastically Transformed Steel Shell Roofs
Received: 8 January 2019 / Revised: 8 February 2019 / Accepted: 11 February 2019 / Published: 14 February 2019
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The article concerns the unconventional architectural forms of buildings roofed with transformed shells made up of thin-walled steel fold sheets, and a parametric description of how they are shaped. Complicated deformations of flanges and webs, as well as the complex static–strength work of [...] Read more.
The article concerns the unconventional architectural forms of buildings roofed with transformed shells made up of thin-walled steel fold sheets, and a parametric description of how they are shaped. Complicated deformations of flanges and webs, as well as the complex static–strength work of the folds in a shell roof, demand the creation of simplified models regarding the parameterization of such shells and their integration with the general forms of the buildings. To obtain favorable results, it was necessary to write computer applications because of both the complicated problems related to the significant limitations of the transformations, as well as the great possibilities of shaping shell roofs by means of directrices of almost free shape and mutual position. The developed procedures enable the prediction of shapes and states of all the folds in the designed shell. They take account of two basic conditions related to these restrictions, which guarantee that the folds encounter little resistance when matching their transformed forms to the roof directrices, and that their initial effort was as low as possible. The developed procedures required solving a number of issues in the fields of architecture, civil engineering, and structures, and are illustrated with an example of shaping one unconventional architectural form. The interdisciplinary study explains a new insight into shaping such forms. Full article
(This article belongs to the Special Issue Responsive Architecture)
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Open AccessArticle Integrating Energy Efficiency into the Municipal Procurement Process of Buildings—Whose Responsibility?
Received: 14 January 2019 / Revised: 8 February 2019 / Accepted: 11 February 2019 / Published: 13 February 2019
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This study addresses the challenges in ensuring energy efficiency and high indoor climate quality with efficient use of public money in the municipal building procurement process. Energy efficient municipal building procurement provides a significant leverage when steering the built environment towards the low-carbon [...] Read more.
This study addresses the challenges in ensuring energy efficiency and high indoor climate quality with efficient use of public money in the municipal building procurement process. Energy efficient municipal building procurement provides a significant leverage when steering the built environment towards the low-carbon economy targets of the EU. Municipal building department professionals need more skills and knowledge to appropriately define the requirements and identify the energy efficient design options accounting for the building’s changing operational environment. This study presents how to systematically integrate energy efficiency in the municipal procurement process of buildings by presenting the list of energy efficiency factors to be included into the procurement process. This list of factors clarifies how indoor climate quality, energy use, and the life cycle economy are related through technological solutions and how the optimal compromise solution can be determined. Furthermore, this list of factors explains the responsibilities in integrating energy efficiency within the municipal building procurement process. Applied in the design of the municipal building the list of factors contributes to more informed and transparent decision-making process. Full article
(This article belongs to the Special Issue Life Cycle Prediction and Maintenance of Buildings)
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Open AccessArticle Adaptive Kinetic Architecture and Collective Behavior: A Dynamic Analysis for Emergency Evacuation
Received: 3 January 2019 / Revised: 6 February 2019 / Accepted: 7 February 2019 / Published: 13 February 2019
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Adaptive kinetic architecture has emerged from a need for innovative designs that adapt to the environment and changing needs of the occupants. Architectural design and modes of egress are critical in an emergency. Flocking describes a certain collective behavior where agents are brought [...] Read more.
Adaptive kinetic architecture has emerged from a need for innovative designs that adapt to the environment and changing needs of the occupants. Architectural design and modes of egress are critical in an emergency. Flocking describes a certain collective behavior where agents are brought together in groups and move as a cohesive unit from place to place. Collective behavior may be observed in microscopic as well as macroscopic environments. Crowd modeling incorporates the study of human behavior, mathematical modeling, and molecular or fluid dynamics. The simulation of agents and their movement in the built environment is beneficial for design professionals, scientists, and engineers. Human behavior in panic situations is notably similar to fluids and molecules. The objective of this research was to evaluate the movement of agents in buildings using discrete dynamic simulation. We used a novel discrete molecular dynamics technique to simulate the evacuation of agents in panic situations. Various adaptive geometric configurations were analyzed for improved crowd flow. Kinetic walls were modeled in order to evaluate design optimization as it relates to rates of egression. This research proposes the use of kinetic walls to improve safety and efficiency during an emergency evacuation. Adaptive geometric configurations show improvements over the conventional design framework. Full article
(This article belongs to the Special Issue Occupant Comfort and Well-Being)
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Open AccessArticle Discrete Element Modeling of the Seismic Behavior of Masonry Construction
Received: 31 December 2018 / Revised: 28 January 2019 / Accepted: 5 February 2019 / Published: 10 February 2019
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Discrete element models are a powerful tool for the analysis of masonry, given their ability to represent the discontinuous nature of these structures, and to simulate the most common deformation and failure modes. In particular, discrete elements allow the assessment of the seismic [...] Read more.
Discrete element models are a powerful tool for the analysis of masonry, given their ability to represent the discontinuous nature of these structures, and to simulate the most common deformation and failure modes. In particular, discrete elements allow the assessment of the seismic behavior of masonry construction, using either pushover analysis or time domain dynamic analysis. The fundamental concepts of discrete elements are concisely presented, stressing the issues related to masonry modeling. Methods for generation of block models are discussed, with some examples for the case of irregular stone masonry walls. A discrete element analysis of a shaking table test performed on a traditional stone masonry house is discussed, as a demonstration of the capabilities of these models. Practical application issues are examined, namely the computational requirements for dynamic analysis. Full article
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Open AccessArticle The Structural Effectivity of Bent Piles in Ammatoan Vernacular Houses
Received: 30 December 2018 / Revised: 1 February 2019 / Accepted: 2 February 2019 / Published: 10 February 2019
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Abstract
Ammatoa Kajang vernacular houses are buildings that have existed for a hundred years as residential house buildings. These traditional houses are unique in their use of bent piles. This research examines the strength of the structural system of Ammatoan vernacular houses based on [...] Read more.
Ammatoa Kajang vernacular houses are buildings that have existed for a hundred years as residential house buildings. These traditional houses are unique in their use of bent piles. This research examines the strength of the structural system of Ammatoan vernacular houses based on said houses’ ability to adapt to various environmental conditions and natural phenomena. This study seeks to enrich these studies by examining the specific structural strength of these buildings. In the face of modernization and extreme climate change, the continued existence of such traditional houses has been threatened. Disaster may strike at any time, and as such we must explore the structural strength of their structures to predict these buildings’ ability to endure such events. This research applies an interpretative model to explore the structural system, using a load test to examine the houses’ structural strength. Although such a model assumes that each building has the same pitch, each house has its own pitch. Therefore, the measurement results cannot be applied generally to describe the structural strength of every Ammatoan house. This research also notes that the pin joint system, material selection, and application of a grounded foundation are factors that promote these buildings’ continued endurance and ability to withstand earthquakes. Full article
(This article belongs to the Special Issue Responsive Architecture)
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Open AccessArticle Time and Cost Overrun in the Saudi Arabian Oil and Gas Construction Industry
Received: 2 December 2018 / Revised: 27 January 2019 / Accepted: 2 February 2019 / Published: 8 February 2019
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Many construction projects exceed time and budget. The Saudi Arabian construction projects are not an exception to this phenomenon. However, the causes of time and cost overrun of Saudi Arabian oil and gas construction projects have never been studied. Thus, this paper endeavors [...] Read more.
Many construction projects exceed time and budget. The Saudi Arabian construction projects are not an exception to this phenomenon. However, the causes of time and cost overrun of Saudi Arabian oil and gas construction projects have never been studied. Thus, this paper endeavors to investigate the main causes of time and cost overrun in Saudi Arabian oil and gas construction projects. Thirty-eight causes of time and cost overrun were identified through the literature and an interview. Responses from 48 professionals based in the Eastern Province of Saudi Arabia were obtained. The respondents were solicited to evaluate the significance of the causes, which were then ranked and a test of agreement was conducted. All survey participants agreed that the five major causes of time and cost overrun, combined, were found to be “changing of design and scope by client during construction”, “poor planning and scheduling of project”, “design errors”, “Inadequate comprehension of scope of work at the bidding stage”, and “underestimating of cost and schedules/overestimating of benefits”. On the other hand, the major cause of time overrun was found to be “changing of design and scope by client during construction”. Finally, the major cause of cost overrun was found to be “underestimating of cost and schedules/overestimating of benefits”, respectively. The findings of this study will be beneficial to project stakeholders who must operate in an industry that is highly sensitive. The findings will also facilitate organizations planning to conduct construction projects in the Saudi Arabian oil and gas industry. Full article
Open AccessArticle Evaluation of Classical Operators and Fuzzy Logic Algorithms for Edge Detection of Panels at Exterior Cladding of Buildings
Received: 28 December 2018 / Revised: 1 February 2019 / Accepted: 1 February 2019 / Published: 6 February 2019
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The automated process of construction defect detection using non-contact methods provides vital information for quality control and updating building information modelling. The external cladding in modular construction should be regularly controlled in terms of the quality of panels and proper installation because its [...] Read more.
The automated process of construction defect detection using non-contact methods provides vital information for quality control and updating building information modelling. The external cladding in modular construction should be regularly controlled in terms of the quality of panels and proper installation because its appearance is very important for clients. However, there are limited computational methods for examining the installation issues of external cladding remotely in an automated manner. These issues could be the incorrect sitting of a panel, unequal joints in an elevation, scratches or cracks on the face of a panel or dimensions of different elements of external cladding. This paper aims to present seven algorithms to detect panel edges and statistically compare their performance through application on two scenarios of buildings in construction sites. Two different scenarios are selected, where the building façades are available to the public, and a sample of 100 images is taken using a state-of-the-art 3D camera for edge detection analysis. The experimentation results are validated by using a series of computational error and accuracy analyses and statistical methods including Mean Square Error, Peak Signal to Noise Ratio and Structural Similarity Index. The performance of an image processing algorithm depends on the quality of images and the algorithm utilised. The results show better performance of the fuzzy logic algorithm because it detects clear edges for installed panels. The applications of classical operators including Sobel, Canny, LoG, Prewitt and Roberts algorithms give similar results and show similarities in terms of the average of errors and accuracy. In addition, the results show that the minor difference of the average of the error and accuracy indices for Sobel, Canny, LoG, Prewitt and Roberts methods between both scenarios are not statistically significant, while the difference in the average of the error and accuracy indices for RGB-Sobel and Fuzzy methods between both scenarios are statistically significant. The accuracy of the algorithms can be improved by removing unwanted items such as vegetation and clouds in the sky. The evaluated algorithms assist practitioners to analyse their images collected day to day from construction sites, and to update building information modelling and the project digital drawings. Future work may need to focus on the combination of the evaluated algorithms using new data sets including colour edge detection for automatic defect identification using RGB and 360-degree images. Full article
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Open AccessArticle Study of the Seismic Response on the Infill Masonry Walls of a 15-Storey Reinforced Concrete Structure in Nepal
Received: 14 December 2018 / Revised: 21 January 2019 / Accepted: 29 January 2019 / Published: 4 February 2019
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Abstract
Following the strong earthquake on April 25, 2015 in Nepal, a team from the University of Porto, in collaboration with other international institutions, made a field study on some of the most affected areas in the capital region of Kathmandu. One of the [...] Read more.
Following the strong earthquake on April 25, 2015 in Nepal, a team from the University of Porto, in collaboration with other international institutions, made a field study on some of the most affected areas in the capital region of Kathmandu. One of the tasks was the study of a high-rise settle of buildings that were damaged following the earthquake sequence. A survey damage assessment was performed to a 15-storey infilled reinforced concrete structure, which will be detailed in the manuscript. Moreover, ambient vibration tests were carried out to determine the natural frequencies and corresponding vibration modes of the structure. The main aim of this manuscript is to present a numerical study concerning the influence of the masonry infill walls in the structure seismic response. For this, three numerical models were built discriminating the situations with and without damage and nondamaged infill walls. Validation and calibration of the numerical model was ensured by comparing the numerical frequencies with those obtained from ambient vibration tests. In addition, linear elastic analyses were carried out, using real accelerograms from the Gorkha earthquake to assess and quantify the major differences between the models in terms of inter-storey drifts ratios, inter-storey shear forces and seismic loadings. Full article
(This article belongs to the Special Issue Masonry Buildings: Research and Practice)
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Open AccessReview Performance Review of Prefabricated Building Systems and Future Research in Australia
Received: 11 October 2018 / Revised: 30 October 2018 / Accepted: 24 January 2019 / Published: 3 February 2019
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Volumetric prefabricated building construction is growing in most developed countries; for example, in Sweden the market share of prefabricated building systems in the housing industry was more than 80%. However, in Australia only approximately 3–4% of new building constructions are prefabricated buildings in [...] Read more.
Volumetric prefabricated building construction is growing in most developed countries; for example, in Sweden the market share of prefabricated building systems in the housing industry was more than 80%. However, in Australia only approximately 3–4% of new building constructions are prefabricated buildings in a year. A major hindrance to the growth of prefab construction in Australia is that systems are developed under commercial and confidential conditions. There are limited publicly-available research and case studies for certifiers, regulators, engineers and academia to provide independent information on the performance, advantages and disadvantages of prefabricated building systems. Independent designers and structural engineers are relying on the strength of the structural and non-structural element, as well as the connections of the prefabricated building systems. This strength is estimated from the “commercial-in-confidence” test of individual components by manufactures, and it might result in undesired outcomes in design. This paper provides an overview of available literature on structural performance, benefits, constraints and challenges of prefabricated building systems. This paper also highlights the research needed on the prefabricated building systems such as full-scale tests, numerical modelling, hybrid simulations, case studies and social and economic assessments. Being supported by sound academic research will increase the market demand for prefabricated building systems in Australia as well as in other countries. Full article
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Open AccessArticle Potential Design of Seismic Vulnerable Buildings Incorporating Lead Rubber Bearing
Received: 25 December 2018 / Revised: 20 January 2019 / Accepted: 21 January 2019 / Published: 3 February 2019
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Abstract
The seismic hazard of vulnerable regions warrants the investigation of new technologies, such as base level isolation by lead rubber bearing (LRB) devices, that can help to mitigate structural damage on seismic prone buildings. The behavior adopting such technologies can be dynamically observed [...] Read more.
The seismic hazard of vulnerable regions warrants the investigation of new technologies, such as base level isolation by lead rubber bearing (LRB) devices, that can help to mitigate structural damage on seismic prone buildings. The behavior adopting such technologies can be dynamically observed in simulated environments and thus serves as a valuable metric for their feasibility. LRB base isolators were incorporated into the design of 16 model buildings to better understand how they affected a building’s seismic response while also providing information on the structural parameters. A total of 12 different types of bearing systems were tested in base isolated (BI) buildings against conventional fixed-base (FB) isolated buildings. The system of each model high-rise building was represented by the finite element package. Static as well as dynamic analysis were conducted using response spectrum analysis (RSA) based on the seismic excitation to determine the influence of the model type in the aseismic design and the alteration in superstructure behavior. The study reveals that the LRB isolators can potentially diminish respective story accelerations, story inertia, and base shear. Use of LRB isolators in BI buildings resulted in a 10–20% reduction in base shear compared to FB buildings. A notable lateral shift of superstructure is offered by LRB-induced flexibility. The reduction of story acceleration for response spectrum varies 30% on lower stories up to 70% on upper stories. The LRB systems with higher characteristic strength and relatively less isolation periods shows better productivity to minimize displacements in the bearing face for dropping structural shift. However, the LRB with comparatively lower characteristic strength and high isolation periods shows the most efficiency in controlling base shear, offering least story accelerations and consenting lower story inertia forces. Full article
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Open AccessArticle Seismic Performance of High-Rise Condominium Building during the 2015 Gorkha Earthquake Sequence
Received: 27 November 2018 / Revised: 26 January 2019 / Accepted: 28 January 2019 / Published: 30 January 2019
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Abstract
On 25 April 2015, a strong earthquake of magnitude 7.8 struck central Nepal including the capital city, Kathmandu. Several powerful aftershocks of magnitude 6.7, 6.9 and 7.3 together with hundreds of aftershocks of local magnitude greater than 4 hit the same area until [...] Read more.
On 25 April 2015, a strong earthquake of magnitude 7.8 struck central Nepal including the capital city, Kathmandu. Several powerful aftershocks of magnitude 6.7, 6.9 and 7.3 together with hundreds of aftershocks of local magnitude greater than 4 hit the same area until May 2015. This earthquake sequence resulted in considerable damage to the reinforced concrete buildings apart from brick and stone masonry constructions. High-rise buildings in Nepal are mainly confined in Kathmandu valley and their performance was found to be in the life safety to collapse prevention level during the Gorkha earthquake sequence. In this paper, seismic performance assessment of a reinforced concrete apartment building with brick infill masonry walls that sustained life safety performance level is presented. Rapid visual assessment performed after the 12 May aftershock (MW 7.3) highlighted the need for detailed assessment, thus, we carried out nonlinear time history analysis using the recorded accelerograms. The building was first simulated for the recorded acceleration time history (PGA = 0.16 g) and the PGA was scaled up to 0.36 g to assess the behaviour of building in the case of the maximum considered earthquake occurrence. The sum of results and observations highlighted that the building sustained minor damage due to low PGA occurrence during the Gorkha earthquake and considerable damage would have occurred in the case of 0.36 g PGA. Full article
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Open AccessArticle Heat Stress Pattern in Conditioned Office Buildings with Shallow Plan Forms in Metropolitan Colombo
Received: 30 November 2018 / Revised: 22 January 2019 / Accepted: 23 January 2019 / Published: 30 January 2019
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Abstract
This paper critically evaluates indoor overheating of multilevel office buildings in Colombo—a tropical warm humid city. The work questions the building morphological characteristics on thermal performance and indoor climate, thus the levels of Building Energy Indices (BEI) of air conditioned buildings. Pattern of [...] Read more.
This paper critically evaluates indoor overheating of multilevel office buildings in Colombo—a tropical warm humid city. The work questions the building morphological characteristics on thermal performance and indoor climate, thus the levels of Building Energy Indices (BEI) of air conditioned buildings. Pattern of heat stress on buildings due to building characteristics and its relationship to the BEI were identified. A study of 87 multilevel office buildings contributed to identify two critical cases in shallow plan form with similar morphological characteristics such as wall-to-window ratio, aspect ratio, orientation, occupant and equipment density, and façade architecture. A comprehensive thermal performance investigation on these two critical cases quantified the heat stress patterns on their facades and thus indoor thermal environments. Indoor air temperature during office hours in 3 m × 3 m multizones across the depths and lengths in these two buildings showed deviations up to 10.5 °C above the set point temperature level (24 °C). Findings highlight the severity of heat stress on air conditioned indoor environments and the need to address this issue for energy sustainability of urban office buildings in the tropics. Full article
(This article belongs to the Special Issue Environmental Impact Assessment of Buildings)
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Open AccessArticle Ultimate Shear of RC Beams with Corroded Stirrups and Strengthened with FRP
Received: 26 December 2018 / Revised: 17 January 2019 / Accepted: 24 January 2019 / Published: 29 January 2019
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Abstract
Transverse reinforcement plays a key role in the response behavior of reinforced concrete beams. Therefore, corrosion of steel stirrups may change the failure mode of elements from bending to shear, leading to a brittle and catastrophic crisis. It is important to strengthen reinforced [...] Read more.
Transverse reinforcement plays a key role in the response behavior of reinforced concrete beams. Therefore, corrosion of steel stirrups may change the failure mode of elements from bending to shear, leading to a brittle and catastrophic crisis. It is important to strengthen reinforced concrete beams with corroded stirrups to enhance the shear resistance. This paper presents a formulation, based on the modified compression field theory, to estimate the ultimate shear of reinforced concrete beams strengthened with FRP, because of stirrup corrosion. The detrimental effect of corrosion on steel stirrup yield strength was taken into account by introducing an empirical decay law. The effective strain of FRP reinforcement was adequately evaluated by considering both debonding and tensile stress rupture. The proposed model was validated against collected experimental results, showing a good ability to evaluate shear strength. Moreover, a numerical analysis was carried out to highlight the role of the key parameters predicting the ultimate shear. Full article
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Open AccessArticle Factors Affecting Contractors’ Bidding Decisions for Construction Projects in Saudi Arabia
Received: 26 November 2018 / Revised: 22 January 2019 / Accepted: 23 January 2019 / Published: 29 January 2019
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Abstract
One of the critical decisions taken by contractors is whether or not to bid for a project. This is due to the complexity and uncertainty surrounding this decision, which is influenced by many factors. Given the above challenge, this study aimed to uncover [...] Read more.
One of the critical decisions taken by contractors is whether or not to bid for a project. This is due to the complexity and uncertainty surrounding this decision, which is influenced by many factors. Given the above challenge, this study aimed to uncover the critical factors affecting the contractors’ bidding decisions in Saudi Arabia-based construction projects. A questionnaire survey, which consisted of 31 factors, was distributed to first-, second- and third-grade contractors. In total, 67 responses were obtained. Median and relative importance index (RII) techniques were adopted for ranking the most critical factors. Based on the received responses, the top six critical factors were “size of the job”, “type of the job”, “company’s strength in the industry”, “designer/design quality”, “rate of return”, and “project cash flow”. The least significant factors were “job start time” and “labor environment (union/nonunion/cooperative)”. The findings of this study show a level of agreement among all contractors about the critical factors. The findings would benefit contractors and subcontractors by increasing their understanding of the major factors affecting the bidding decision process. Contractors armed with such valuable information will be better able to enhance their bidding decision-making process in terms of efficiency and effectiveness. Full article
Open AccessArticle Locating Hidden Elements in Walls of Cultural Heritage Buildings by Using Infrared Thermography
Received: 31 December 2018 / Revised: 22 January 2019 / Accepted: 25 January 2019 / Published: 28 January 2019
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Abstract
The structure of Tvrđa and its buildings date back to the Middle Ages. Tvrđa represents the Old Town of the city of Osijek and the best-preserved and largest ensemble of Baroque buildings in Croatia. After the withdrawal of the Ottomans in 1687, during [...] Read more.
The structure of Tvrđa and its buildings date back to the Middle Ages. Tvrđa represents the Old Town of the city of Osijek and the best-preserved and largest ensemble of Baroque buildings in Croatia. After the withdrawal of the Ottomans in 1687, during the 18th century, the Austro-Hungarian administration systematically formed a new fortification system, regulated streets and squares and built a large number of military objects. Tvrđa took its present form in the 19th century and has kept it since then. Investigating the historical development of individual buildings, in addition to archival sources and existing architectural documentation, the obvious source of information are the buildings themselves. The aim of this paper is to explore the possibilities of using infrared thermography to find structural elements and hidden openings in historic buildings in Osijek’s Tvrđa. This paper describes the exploration of the 18th century openings on the facades of the former Kostić houses. The facades were bricked into the walls in the 19th century because houses were reused and their purposes changed from commercial to residential. Infrared thermography is often a starting, nondestructive testing method (NDT) for building analyses. This paper presents thermographic analyses of two buildings. The analyses were carried out in December 2017 and January 2018. Using a steady-state thermographic analysis of a building envelope as the first step, the audit was continued with step heating (SH) of an interest point where changes in a thermal pattern were expected due to additional bricking. Heat flux was generated by the usage of a heat gun for paint removal. Full article
(This article belongs to the Special Issue Non-destructive Testing for Building Evaluation)
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Open AccessArticle Assessment of the Applicability of Sustainable Epoxy Composites Containing Waste Rubber Aggregates in Buildings
Received: 13 December 2018 / Revised: 18 January 2019 / Accepted: 23 January 2019 / Published: 24 January 2019
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Abstract
The dynamic development of the automotive industry and improvements in quality of life have caused a significant increase in the production of car tires. Unfortunately, when the useful life of these products comes to an end, the problem of their disposal arises. The [...] Read more.
The dynamic development of the automotive industry and improvements in quality of life have caused a significant increase in the production of car tires. Unfortunately, when the useful life of these products comes to an end, the problem of their disposal arises. The article presents the results of tests of epoxy mortars in which granules made from waste tires were used as a substitute for sand in the amount of 0, 20, 40, 60, 80 and 100% vol. respectively. The available literature lacks information about resin composites that arise with such a large or complete replacement of sand with rubber waste. Along with the increase in the content of waste, the values of strength parameters of composites decreased; however, a material characterized by very low water absorption, that is lightweight and with a low thermal conduction coefficient was obtained. Using the ADINA program, numerical simulations were carried out regarding the temperature distribution in a part of the building structure containing modified rubber mortar. The results of the simulation confirmed the possibility of practical use of the obtained composite due to its good thermal insulation properties. This approach to testing composites modified with rubber waste is innovative. Full article
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Open AccessArticle Seismic Evaluation and Strengthening of an Existing Masonry Building in Sarajevo, B&H
Received: 17 December 2018 / Revised: 17 January 2019 / Accepted: 18 January 2019 / Published: 22 January 2019
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Abstract
A significant number of old unreinforced load-bearing masonry (URM) buildings exist in many countries worldwide, but especially in Europe. In particular, Bosnia and Herzegovina has an important stock of masonry buildings constructed from the 1920s until the 1960s without application of any seismic [...] Read more.
A significant number of old unreinforced load-bearing masonry (URM) buildings exist in many countries worldwide, but especially in Europe. In particular, Bosnia and Herzegovina has an important stock of masonry buildings constructed from the 1920s until the 1960s without application of any seismic code, due to their nonexistence at that time. With the 1963 Skopje earthquake, this class of buildings were shown to be rather vulnerable to seismic actions, which exhibited serious damage. This article assesses the seismic vulnerability of a typical multi-storey residential unreinforced load-bearing masonry building located in the heart of Sarajevo, which may be exposed to an earthquake of magnitude up to 6 by Richter’s scale. The buildings of this kind make up to 6% of the entire housing stock in the urban region of Sarajevo, while in Slovenia this percentage is much higher (around 30%). The analysis of a typical building located in Sarajevo revealed its drawbacks and the need for some kind of strengthening intervention to be implemented. Additionally, many structures of this type are overstressed by one to two additional floors (not the case of the analyzed structure) constructed from 1996 onwards. This was due to the massive population increase in the city center of Sarajevo and further increased the vulnerability of these buildings. Full article
(This article belongs to the Special Issue Masonry Buildings: Research and Practice)
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Open AccessArticle The Effects of Information Format and Spatial Cognition on Individual Wayfinding Performance
Received: 20 December 2018 / Revised: 14 January 2019 / Accepted: 17 January 2019 / Published: 22 January 2019
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Abstract
Buildings with spatially complex interiors poise unique challenges during operations and maintenance. A complex interior makes wayfinding difficult, which can inhibit daily occupants from finding their desired location. Additionally, it can hamper emergency responders and evacuations during extreme emergency events. An experiment was [...] Read more.
Buildings with spatially complex interiors poise unique challenges during operations and maintenance. A complex interior makes wayfinding difficult, which can inhibit daily occupants from finding their desired location. Additionally, it can hamper emergency responders and evacuations during extreme emergency events. An experiment was conducted to analyze the effects of different information formats and spatial cognition on individual wayfinding in unknown environments. Participants were asked to memorize either a set of two-dimensional (2D) drawings or a three-dimensional (3D) model before navigating through a series of checkpoints in an unfamiliar environment. Individual wayfinding is dependent on an individual’s use of route knowledge or survey knowledge. Route knowledge was assessed from the start of the route to Checkpoint A (i.e., the first checkpoint). Meanwhile, survey knowledge was assessed from Checkpoint A to Checkpoint B. Spatial cognition of participants was measured by administering the card rotation and cube comparison tests. The research found that 3D models have a beneficial impact on the success of individual wayfinding. Furthermore, the success rate of the participants with a low spatial cognition improved significantly when using a 3D model rather than a set of 2D drawings. However, the success rates of participants with a high spatial cognition were not affected by the format of information. While the above results are significant, more experimentation is needed to confirm whether 3D information does effectively lower cognitive demand. Full article
(This article belongs to the Special Issue BIM in Building Repair and Maintenance)
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Open AccessArticle Photocatalytic Functionalized Aggregate: Enhanced Concrete Performance in Environmental Remediation
Received: 2 December 2018 / Revised: 25 December 2018 / Accepted: 4 January 2019 / Published: 22 January 2019
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Abstract
Engineering of effective photocatalytically active structures is of great importance as it introduces a solution for some existing air pollution problems. This can be practically achieved through the bonding of particulate photocatalysts to the surface of construction materials, such as aggregates, with a [...] Read more.
Engineering of effective photocatalytically active structures is of great importance as it introduces a solution for some existing air pollution problems. This can be practically achieved through the bonding of particulate photocatalysts to the surface of construction materials, such as aggregates, with a suitable stable binding agent. However, the accessibility of the photocatalytically active materials to both the air pollutants and sunlight is an essential issue which must be carefully considered when engineering such structures. Herein, different amounts of commercial TiO2 were supported on the surface of quartz sand, as an example of aggregates, with a layer of silica gel acting as a binder between the photocatalyst and the support. The thus prepared photocatalytically active aggregates were then supported on the surface of mortars to measure their performance for NOx removal. The obtained materials were characterized by electron microscopy (SEM and TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and UV-vis Absorption Spectroscopy. Very good coverage of the support’s surface with the photocatalyst was successfully achieved as the electron microscopic images showed. FTIR spectroscopy confirmed the chemical bonding, i.e., interfacial Ti–O–Si bonds, between the photocatalyst and the silica layer. The photocatalytic activities of the obtained composites were tested for photocatalytic removal of nitrogen oxides, according to the ISO standard method (ISO 22197-1). The obtained aggregate-exposed mortars have shown up to ca. four times higher photocatalytic performance towards NO removal compared to the sample in which the photocatalyst is mixed with cement, however, the nitrate selectivity can be affected by Ti–O–Si bonding. Full article
(This article belongs to the Special Issue Environmental Impact Assessment of Buildings)
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