Scipedia: XV International Conference on Durability of Building Materials and Components (DBMC 2020)

A 3D Model for Building Condition Assessment

Scipedia content — Mon, 28 Sep 2020 12:58:23 +0200

The aim of the paper is to analyze practical aspects with use of 3D Model for accurate building condition assessment. Use of fully interactive visualization methods from a technical condition assessment platform going to be, especially taking into consideration current COVID-19 scenarios, a very supportive tool for the massive inspection of building stocks, particularly in big residential areas. The authors present the approach based on high-performance images that were captured by Unmanned Aerial Vehicles (UAVs). The next step is the generation of a 3D model and orthophotos of building facades. The graphical information together with tables of attributes will allow the interactive geo-referenced management and assessment, that is proposed as a form of interactive cooperation. The idea of this approach corresponds widely with the Building Information Modeling aims. The authors introduce the methodology, stages of the inventory and follow-up process carried out within the platform requirements together with advantages of the visualization techniques, basing on a particular case study. Technical details about the information system and the analysis connected with the visualization utility will be presented and illustrated.

A Comprehensive Description of a Low-Cost Wireless Dynamic Real-Time Data Acquisition and Monitoring System

Scipedia content — Fri, 25 Sep 2020 13:14:57 +0200

Nowadays, low-cost sensors and acquisition devices have been emerging as an obvious solution to many innovative applications such as Structural Health Monitoring (SHM) systems. In this paper, issues regarding dynamic data acquisition, as well as their respective solutions, are presented. Moreover, a comprehensive description through-out an inexpensive sensor network system using opensource hardware for a real-time acceleration data acquisition has been presented. The platform consists of an accelerometer, an Arduino board, and a computer as a data recorder and presenter. Data is recorded through an efficient microcontroller code that can provide a considerable reading frequency (up to 300Hz). Using Python, instant acceleration recording for all the three axes has been done. It is shown how the performance of the proposed system is efficient for the field of SHM systems.

A Framework for Installation Impact Analysis on Building Performance

Scipedia content — Fri, 25 Sep 2020 13:15:54 +0200

Product installation during the construction process impacts the overall performance and durability of a building. However, when the building construction industry fails to address installation quality the product performance is affected. This research explores the importance of optimized product installation and how it affects product performance. During the installation period, standard product performance can be affected by the information known about the product and the amount of time put into the assembly of the product. The building products can vary from insulation, A/C units, water heaters, etc. An installers‘ workmanship can impact standard product performance if they have limited knowledge about the product and its operational functionality. The products‘ prescribed functionality could be altered due to less than standardized installation practices. Improper installation of a product can lead to major deviations in performance that can increase maintenance costs over the lifetime of the product in addition to adverse effects of the product during its normal life cycle. Labor sensitivity is an underrepresented aspect of building construction that contributes to the problem of energy inefficiency. The goal of this work is to develop a metric that can quantify how relatively sensitive a building product and overall building performance is to the efforts of time and knowledge, specifically during the installation process. From this metric, the impact of installation on performance for different products can be compared through numerical values, highlighting products that require special care during the installation process to ensure desired performance.

A Joint Inversion Approach of Capacitive and Resistive Measurements for the Estimation of Water Saturation Profiles in Concrete Structures

Scipedia content — Wed, 23 Sep 2020 15:40:05 +0200

Concrete is a construction material that is well known for its durability. However, it is exposed to environmental attacks that lead to the penetration of aggressive agents such as water and chlorides, thus, threatening its durability and service life. Within this context and exploiting the sensitivity of the electromagnetic properties of concrete to its water content, the literature suggests determining water saturation profiles using non-destructive techniques. For instance, measuring the electrical resistivity at several points of the surface of the concrete structure can lead to an estimate of the resistivity depth profile. Then, after a calibration step, the water saturation depth profile can be obtained and the durability can be assessed. Similarly, the water depth profile can be assessed by dielectric permittivity measurements. In this paper, we propose a new inversion scheme based on the combination of both resistive and capacitive measurements: resistivity and permittivity measurements are inverted jointly to estimate the water saturation profile in concrete. Numerical experiments with simulated data show that information gathered from the two measurements enriches the inversion process, leading to the determination of more reliable water saturation profiles.

A Maintenance Management Model. Upgrading and Experimentation

Scipedia content — Mon, 21 Sep 2020 13:23:43 +0200

The paper deals with the first results of the activities of BIG Building Innovative Governance srl, Academic Spin-Off and Innovative Start Up, which provides smart services for Building Maintenance and Facility Management also launching circular R&D actions in the relative reference areas. The contribution introduces some actions actually in progress geared to upgrading the Maintenance Management Model, M3, specifically aimed at managing the life cycle of buildings. The current stage of development corresponds to a TRL 4. TRL 8 is that expected by the end of 2020. Characterized by interconnectivity and scalability, the Maintenance Management Model is a dynamic, collaborative and implementable system, whose architecture consists of three separated but strongly interconnected devices: an information interface system, a collaborative platform, a remote cloud. An ICT network infrastructure able to activate using BIM models (IFC and COBie standards) circular information workflows between all operators and/or users involved in Maintenance and Facility Management processes. It allows the development and/or implementation of information management and sharing models based on Open Data and Semantic Web. Its use will also promote shared lexicons and the circulation of knowledge within a holistic process of managing information from and for Maintenance. The use of BIM models and the possibility of collecting and managing a large amount of data will be oriented to the structuring of information feedback databases according to ISO 15686 guidelines. In this way, available information can be usefully transferred in life cycle assessments and service life prediction of materials and components.

A Methodology for Assessment of Building Assembly Air Leakage Moisture Response, Condensation Risk, and Expected Durability When Subjected to Projected Future Climate Loads

Scipedia content — Wed, 23 Sep 2020 15:40:12 +0200

It was determined that the ability to assess the required performance of an air barrier assembly could now be supported using modern computational hygrothermal simulation techniques coupled with historical and future climate data and the new durability methodology developed as part of the updated 2019 CSA S478 Guideline for Durability of Buildings.

A New Alkali-Silica Reaction (ASR) Mitigation Technology - Part I: Comparing with Li, Ca, Al Salts, and Densified Silica Fume

Scipedia content — Tue, 22 Sep 2020 17:34:20 +0200

Alkali-silica reaction (ASR) is a major concrete durability problem. The occurrence of ASR results in significant maintenance and reconstruction costs to concrete infrastructures all over the world. Ever since Stanton (1940) discovered the expansive characteristics of ASR in 1940, there has been much speculation as to the cause and actual mechanism of expansion. Current market solutions are not always sustainable, such as hauling non-reactive aggregates or fly ash from long distance; or use of Li-based chemical admixture that is facing challenge of raw material‘s availability. The current article will present a patent pending technology which provides a commercial solution for mitigating the ASR. The ASR mitigating effect of this technology is compared with lithium, calcium, and aluminum salts, and densified silica fume.

A Nonparametric Statistical Model for the Selection of Significant Variables Acting in the Deterioration of Built Fa?ades

Scipedia content — Mon, 28 Sep 2020 12:58:17 +0200

Serrat and Gibert (2011) introduced the use of survival analysis techniques for the study of time-to-failure in the facades of a building stock. Those techniques have been implemented in a predictive system that incorporates the inspection methodology together with the statistical methodology. The system proposes a network of urban laboratories for building research analysis and information with the aim of modelling the degradation time based on the information from all the cities participating in the project, from a multiscale perspective. The approach is population based, that is from the manager of the building stock point of view, in order to obtain information on the evolution of the stock across time, and to help the manager with decision making process on global maintenance strategies. However, for an efficient decision making it is crucial to determine those covariates -like materials, morphology and characteristics of the facade, orientation or environmental conditions- that play a significant role in the progression of different failures along the façade service life. The proposed platform also incorporates an open source GIS plugin that includes survival and test moduli that allow the investigator to model the time until a damage when taking into account the variables collected during the inspection process. The aim of the paper is to introduce the methodology and the modelling strategy for the deteriorating process of an urban front. The contribution will be illustrated with a case study located in the city of L’Hospitalet de Llobregat (Barcelona, Spain) in which more than 14,000 facades have been inspected and analyzed.

A Probabilistic Model for the Evolution of Porous Structure Caused by Solid-Phase Precipitation/Dissolution within Building Materials

Scipedia content — Tue, 22 Sep 2020 17:43:16 +0200

Saline intrusion is a critical issue in building material because of the severe damages caused by the salt precipitation/dissolution process, especially for the porous material, which has good connectivity. When porous material is exposed to aggressive ambient, the pore structure, not only porosity but also pore size distribution, will be altered by salt precipitation/dissolution. As one of the most significant characteristics in the porous material, pore size distribution is always paid much attention in many literatures. However, a quantitative and practical determination method is still absent. This work aims to establish a probabilistic model to investigate the pore size distribution induced by solid-phase precipitation/dissolution. First, a lognormal distribution is proposed for the simulation of initial pore size distribution tested by the MIP method. Then we develop a probabilistic-based porous network to represent the evolution of microstructure due to precipitation/dissolution. To this end, two different transformation models are constructed to interpret the relation between initial pore radius and modified pore radius before and after precipitation/dissolution. With this probabilistic-based porous network, we could illustrate the precipitated profiles that evolve near the capillary interface during the salt precipitation/dissolution process for a given porosity and water saturation degree. Such a method could be used to interpret the mechanism of the local precipitation/dissolution process in pore scales, which cannot be implemented by experimental measurements.

A Risk-Based Approach for Quantifying Durability and Life-Expectancy of the Wall-Foundation Construction Detail in Timber Buildings

Scipedia content — Thu, 17 Sep 2020 16:30:14 +0200

Understanding and predicting the durability of timber structural components of buildings can lead to a more reliable and efficient use of this material in constructions. The work described herein presents a methodology to assess the life-expectancy of wall-foundation details in timber buildings based on the estimation of the durability of the timber structural element. Risk classes were defined starting from the inputs from the most relevant standards addressing the durability of timber available in Europe. The attribution of a risk class to the wall-foundation detail requires decision trees that consider the key aspects that affect the durability of this construction detail in the case of fungal attack. The methodology was then applied to three case studies and the results were compared to the observations from onsite inspections carried out on the decayed structural timber elements. The present work represents the first step towards the development of a tool capable of predicting the durability of timber components within the building structure. The work reported herein was carried out within the framework of the TSafe project.

A Spatially Continuous Driving Rain Map of India at 0.5��0.5�� Gridded Scale

Scipedia content — Mon, 21 Sep 2020 13:00:34 +0200

Driving rain is one of the most critical sources of moisture affecting the hygrothermal and durability performance of building envelopes. The estimation of severity in terms of annual driving rain indices using annual and monthly weather data (aaDRI and maDRI respectively) aids towards contemplating potential moisture loads, and hence in the efficient design of buildings in the geographical area of interest. In this study, monthly and annual gridded datasets of wind and rainfall, pertaining to the thirty-year period of 1988-2017 have been used to design a spatially continuous driving rain map for India at 0.5��0.5��(lat./long.) resolution. The observations reveal that the use of annually averaged data leads to underestimation of the driving rain severity thereby highlighting the inefficiency of a coarser temporal scale. A linear relationship has subsequently been developed to enable refinement of aaDRI into maDRI. The analysis of the monthly driving rain map reveals that the entire western coastal belt and a few regions in the north-eastern part of the country observe high to severe exposure conditions. Furthermore, a trend analysis of the yearly driving rain index values reveals statistically significant decreasing trends over the northern and eastern regions of the country, whereas increasing trends in the shielded regions surrounding central India is observed.

A Vector Scale of Severity of Damages in Buildings

Scipedia content — Mon, 28 Sep 2020 12:58:29 +0200

In the context of the existing buildings, along the recent years the concept of maintenance has changed from corrective maintenance to preventive maintenance, which is based in part on periodic inspections. There is ample evidence that preventive maintenance is more efficient than corrective maintenance, since severe deteriorations that may represent danger to people are avoided, and also money is saved. To make periodic inspections of the buildings is useful to quantify the extent to which deficiencies are severe or not, in order to facilitate decision making and prioritize therapeutic interventions. To this purpose many scales have been used and are used to assess the degree of gravity of the damages in constructive elements. But it is important to say that there is no common consensus and these scales are different between them according to the study to which they belong. Thus, the main goal of this article is to propose a methodology for calculating the degree of severity of damages in buildings, which is of widespread use. This calculation method, which is in distribution and in scalar, lets to calculate the severity index of systems and of the entire building, and it is easy to use and flexible.

Airborne Algal Growth on the Roofs of Membrane-Structured Residences in a Cold Areas of Japan

Scipedia content — Wed, 23 Sep 2020 15:40:45 +0200

Discoloration of building facades due to airborne algae is observed in our surroundings. The growth conditions of these algae are not fully clear yet, and efficient preventive measures have not yet been determined. This study was aimed at investigating the influence of ambient environment and building structure on algal growth. A residential building in the cold region of Japan was surveyed. The roof was a multilayered structure consisting of a semi-transparent film, an air layer, an outside insulation layer, and was supported by rafters. The soiled state was visually observed and recorded through pictures, and seemed to be particularly increased in autumn. Several black stripes appeared on the northeast (NE) roof four months after its cleaning. The soiling first appeared on the film backed by the rafter, and then extended to the film backed by the air layer. It rarely appeared on the southeast roof. The roof-surface temperature was measured and a stripe-shaped distribution was observed. The temperature of the film with rafter was higher and lesser than that of the film with the air layer during the night and in the early morning, respectively. Although condensation occurred nightly, its frequency showed no orientational difference. Algae can die when exposed to a temperature higher than 40 ��C. The southwest roof had the longest period of a surface temperature over 40 ��C, while the northwest (NW) roof had the shortest period of this surface temperature. These measurements corresponded well to the survey results according to which soiling mainly occurred on the NE and NW sides of roofs. The time for algal growth was estimated assuming that algae can grow at surface temperatures between 0 and 40 ��C.

An Experimental Evaluation of the Thermal Performance of Felt Type Vegetated Facade System

Scipedia content — Mon, 21 Sep 2020 12:25:24 +0200

Vegetated facade systems (VFS) have been used as green building envelope systems in recent years. Using VFS for ecological strategies and evaluating thermal performance of these sytems are not a new concept. However, there is not any experimental study in literature which evaluates thermal performance of felt type VFS applied on an insulated existing building wall which is located in Csa climate during cooling and heating periods. Hence, an experimental study was conducted to measure thermal performance of felt type (type which used felt material as growing media) VFS in Kocaeli (under Csa climate). Test results indicate that in day time with high amount of solar radiation, felt type VFS decreased exterior surface temperatures of an insulated existing wall by maximum of 30��C. Also, interior surface temperatures of vegetated facade were lower than interior surface temperatures of reference facade with the maxiumum difference of 1.8��C. Although high differences between exterior surface temperatures of vegetated and reference walls were observed, there was no significant difference between interior surface temperatures of vegetated and reference walls. This is due to the fact that existing building exterior wall assembly includes 5 cm thickness expanded thermal insulation material which enchance thermal performance of brick wall. In addition, indoor air temperatures behind both facades were close to each other, and were not suitable according to ISO 7730 and ASHRAE 55 Standards comfort range for representative summer days with high ambient air temperatures. Nevertheless, indoor air temperatures behind vegetated facade were in the comfort range in the fall representative day which required cooling, while indoor air temperatures behind reference facade were not in the comfort range in summer representative day.

An Experimental Study on the Thermal Conductivity of Concrete Containing Coal Bottom Ash Aggregate

Scipedia content — Wed, 23 Sep 2020 15:38:53 +0200

Thermal conductivity plays a significant role in efficient energy usage, especially in the construction field. Low thermal conductivity is preferable because lower thermal conductivity will increase the thermal insulation provided by the concrete and reduce the heating and cooling costs for residential and commercial buildings. To accomplish this goal, porous materials can be considered for use in concrete. Additionally, researchers have had challenges producing high-strength concrete with low thermal conductivity. Therefore, this study aims to investigate the effects of replacing crushed fine aggregates with coal bottom ash (CBA) on the thermal conductivity and mechanical properties of high-strength concrete. The concrete properties, including unit weight, compressive strength, and thermal conductivity, were measured. The experimental results revealed that the thermal conductivity of the CBA concrete decreased as the unit weight of the CBA concrete decreased, and the thermal conductivity also decreased as the compressive strength decreased. Finally, the relationships between the thermal conductivity, unit weight, and compressive strength of the CBA concrete were also examined.

Analysis of Change of Physical Properties of Organic Repair Products due to Fire Exposition

Scipedia content — Wed, 23 Sep 2020 15:41:33 +0200

Organic repair products for concrete can be exposed to accidental incidents, like fire. The increase of temperature produces a modification in some of their properties. In general, these types of repair products have organic fibers to increase their tixotropic properties, but they are more sensible to the high temperature than the Portland cement or aggregates. In order to analyze the behavior of organic repair mortars with temperature three types of repair mortars are studied. These repair products have the organic components composed by acetate fiber of polyvinyl like Vinyl Acetate Acrylate (VAA), Copolymer of Vinyl Acetate Vinyl Versatate (VeoVA) and Acrylic polymers fibres. The repair products are tested increasing the temperature from 1.7?C /min until 200?C, 400?C or 600?C respectively during 20 minutes. After that, the samples are cooled in four different cooling conditions two of them slow and two others fast, and with and without oxygen. These conditions are used in order to simulate the different conditions that can occur during the cooling after fire. After the testing the visual aspect, the color and brightness and the open porosity is analyzed in each condition of test. In this work the relationship between the temperature of exposition, the cooling conditions and the change in some physical properties are studied.

Analysis of Steel Bars in Corrosion Process after 70 Years of Natural Aging.

Scipedia content — Tue, 22 Sep 2020 17:42:50 +0200

Reinforced concrete structures are commonly used in civil engineering. However, the number of deteriorations in these structures is increasing, especially problems related to steel corrosion. Also, according studies, corrosion is responsible for about 3.5 % of annual GDP with recovery costs in world. Thus, this study analyzed the corrosion of steel bars at 70-year-old, which are in corrosion process by natural aging. Tests were performed to analyze the bars microstructure, using SEM and EDS, as well as analysis of the current mechanical characteristics, with tensile test. Through SEM, it was possible to measure the layer of the corrosion products formed at the samples edge, and to observe the fragility of this region, with the presence of several microcracks. EDS test contributed to verify the oxygen difference from the nucleus until to the specimen edge. It was possible to notice that in the edge, presence of oxygen is much greater. In the mechanical tests, by the tensile test, the samples do not reach the minimum elongation and the limit of resistance prescribed in the standard. Thus, it is believed after 70 years of natural aging, the samples are in advanced process of corrosion, with edges worn out, and no comply with the minimum mechanical requirements.

Analysis of the Variation of Thermal Conductivity of Rigid Polyisocyanurate Foam (PIR) in The Context of Aging

Scipedia content — Mon, 21 Sep 2020 12:59:44 +0200

For most building insulation materials, dependency of the thermal conductivity on temperature is close to linear, and it increases with rising materials temperature, but the thermal conductivity of the polyisocyanurate foam (PIR) increases in the lower temperature range, so the heat transfer through the partition insulated with this material is increased in the cold season. The thermal conductivity of PIR also increases during the aging process, especially during the later operating period, which is not covered by the standard aging procedure used to determine the declared thermal conductivity value. Also, there is a lack of information how PIR reacts to the certain temperatures and other climate conditions, and how fast it loses its thermal properties. The aim of this experimental research was to analyse the change of the thermal conductivity depending on aging temperature. 30, 50mm thick PIR samples were prepared for the test, and the thermal conductivity of all specimens was measured at the standard conditions prior to the start of the test using the heat flow meter FOX 314, and again after each stage of aging, when the samples were kept at the certain temperature for 21 days. The results showed that the thermal conductivity of PIR increases more (up to 10 %) when kept at higher temperatures (+50 ��C, and +70 ��C), and after specimens undergo negative temperatures (-18 ��C) it has a minor influence to the change of thermal conductivity of PIR.

Application of Pro-Ecological Building Technologies in Contemporary Architecture

Scipedia content — Fri, 25 Sep 2020 13:22:09 +0200

Structural and material solutions of modern buildings are an important element of considerations in accordance with the idea of sustainable design, in which the aim is to minimize their negative impact on the environment. These searches turn towards low-tech technology, which uses natural and low-processed materials, which are possible to obtain in selected locations. Construction in the raw earth technology is a modernization of the traditional technology, in which it is possible to apply pro-ecological values associated with the used material. The paper presents research on insulation properties of walls in an experimental earth building located in Pas??k in Poland. The aim of the research was to determine the potential of the applied raw earth technology in a local climate. The accepted design assumptions were verified due to the effects achieved in the empirical research on the thermo-humidity conditions in an experimental building. On the basis of the conducted research with the use of specialized tools, the positive and negative sides of the selected technology and building material were determined.

Application of Soft Computing Methods to Increase Sustainability in Construction

Scipedia content — Wed, 23 Sep 2020 15:37:59 +0200

In the last three decades the soft computing methods were used by the research community in almost every branch of construction, providing successful and convenient solutions for different problems in civil engineering. This paper presents some of the applications of these methods - especially neural networks (NN) and support vector machine (SVM) - in sustainable construction, i.e. its economic, social and environmental aspects. Soft computing applications were made in the last several years by our research team at the Faculty of Civil Engineering in Skopje, N. Macedonia, in collaboration with other authors from our and other countries. Several predictive models were developed using: general regression neural network (GRNN), support vector machine (SVM) and radial basis function neural network (RBF NN), using predictive modelling software DTREG. Applications of these models cover most of the aspects of sustainability in construction. Models were focused on predicting: road structure construction costs, bidding price in construction, sustainability assessment at early facilities design phase, predicting construction cost and construction time and predicting consumption of energy in buildings. Some of the mentioned developed predictive models are hybrid, composed of process-based and data driven models which contributed very much to the improvement of the accuracy of the predicting. The general conclusion is that the soft computing methods are a useful tool for developing models in the area of all aspects of sustainability and their application can lead to increasing sustainability in construction.