Compact Embedded Wireless Sensor-Based Monitoring of Concrete Curing

This work presents the design, construction and testing of a new embedded sensor system for monitoring concrete curing. A specific mote has been implemented to withstand the aggressive environment without affecting the measured variables. The system also includes a real-time monitoring application operating from a remote computer placed in a central location. The testing was done in two phases: the first in the laboratory, to validate the functional requirements of the developed devices; and the second on civil works to evaluate the functional features of the devices, such as range, robustness and flexibility. The devices were successfully implemented resulting in a low cost, highly reliable, compact and non-destructive solution.Fondos FEDER IDI-2010044

Methodologies and Applications Review

Funding Information: The Authors acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via the project UIDB/00667/2020 (UNIDEMI). Pedro M. Ferreira also acknowledges FCT-MCTES for funding the PhD grant UI/BD/151055/2021. Publisher Copyright: © 2022 by the authors.Sensing Technology (ST) plays a key role in Structural Health-Monitoring (SHM) systems. ST focuses on developing sensors, sensory systems, or smart materials that monitor a wide variety of materials’ properties aiming to create smart structures and smart materials, using Embedded Sensors (ESs), and enabling continuous and permanent measurements of their structural integrity. The integration of ESs is limited to the processing technology used to embed the sensor due to its high-temperature sensitivity and the possibility of damage during its insertion into the structure. In addition, the technological process selection is dependent on the base material’s composition, which comprises either metallic or composite parts. The selection of smart sensors or the technology underlying them is fundamental to the monitoring mode. This paper presents a critical review of the fundaments and applications of sensing technologies for SHM systems employing ESs, focusing on their actual developments and innovation, as well as analysing the challenges that these technologies present, in order to build a path that allows for a connected world through distributed measurement systems.publishersversionpublishe

IoT pohjainen betonin kuivumisolosuhteiden hallinta uusien asuinrakennuskohteiden tuotantovaiheessa

Recently, moisture related problems, particularly in relatively new residential buildings, have drawn a significant amount of media attention. Consequently, numerous researches and studies have been conducted in order to detect, analyse, and prevent future moisture problems from occurring. Unwanted moisture in the structures has been found to cause both considerable financial losses and severe health issues due to potential growth of mold, dust mite presence and VOC emissions. There are many causes to the above-mentioned problems throughout the building life cycle, including inadequate design, negligent construction and inappropriate use and maintenance. One of the major single causes is construction moisture that is not properly controlled and removed during the construction phase. The aim of this Master’s thesis is to determine whether it is technically possible and financially feasible to actively steer the construction site management to maintain at all times indoor conditions that are optimal for drying of concrete with the help of real-time IoT-based monitoring technology, and additionally support or even replace current humidity measurement process. Secondary aim is to determine which wireless area network (WAN) is best suited for achieving the former aim, both from technical and financial point of view, taking into account the constantly changing construction environment conditions. The theory section is compiled as a literature survey containing previous studies and literature on concrete including the Finnish building code, the Building Information Ltd and the Confederation of Finnish Construction Industries (CFCI) the as the main source, due to the fact that the concreting conditions in Finland and other Nordic countries are rather challenging, also implying that the quality of Finnish concrete technology is very advanced. The empirical part consists of building, testing and installing the IoT-architecture on the pilot construction site, collecting, analysing and storing sensor data, and developing a web based application designed for the construction site management. The thesis proves that real-time control of drying conditions provides significant financial benefits by cutting down construction time, by optimizing the use of heating energy and by reducing the need for traditional moisture measurements. The case study also shows that the construction management is benefitting greatly from a supplementary mobile web application highlighting the importance of building physics in the drying process.Viime aikoina etenkin uudehkojen asuinrakennusten kosteus- ja homeongelmat ovat saaneet huomattavaa näkyvyyttä mediassa, minkä seurauksena lukuisia uusia tutkimuksia on tehty selvittääkseen ongelmien perimmäiset syyt sekä pystyäkseen ehkäisemään tulevia ongelmia. Kosteusvaurioiden syiksi on todettu mm. uusien energiamääräysten mukaiset erityisen haasteelliset arkkitehti-, rakenne- ja talotekniikkasuunnitelmat, rakennustuotannon ylikuumentuminen ja sitä kautta kasvanut riski työmaalla tapahtuviin virheisiin sekä vääränlainen käyttö ja ylläpito. Yksi isoimmista yksittäisistä syistä on kuitenkin rakennuskosteus eli rakennusmateriaalien kuten betonielementtien valmistuskosteus ja rakenteisiin rakennusaikana päässyt kosteus, jota pitäisi pystyä hallitsemaan nykyistä paremmin. Diplomityön tavoitteena on selvittää, voiko reaaliaikaisella, IoT-teknologiaan perustuvalla työmaan rakennusaikaisten ulko- ja sisäolosuhteiden seurannalla ja betonin kosteuden mittauksella aktiivisesti ohjata työmaan johtoa betonin kuivumiselle optimaalisten olosuhteiden ylläpitämisessä sekä täydentämään tai jopa mahdollisesti korvaamaan nykyistä kosteudenmittausprosessia. Toissijaisena tavoitteena on selvittää, mikä langaton tiedonsiirtoverkko sopii kyseisten tavoitteiden saavuttamisessa parhaiten, sekä tekniseltä toteutukseltaan että kustannustehokkuuden näkökulmasta, ottaen huomioon haastavat ja muuttuvat työmaaolosuhteet. Tutkimuksen teoreettinen osuus on toteutettu kirjallisuuskatsauksena. Tämän tutkimuksen lähteinä on käytetty pääasiassa Suomen rakentamismääräykokoelman, Rakennustiedon (RT), Betoniteollisuus Ry:n ja Betoniyhdistys Ry:n (BY) betonirakenteiden ohjeita ja määräyksiä, johtuen siitä, että Suomessa ja muissa pohjoismaissa rakennusolosuhteet ovat hyvin haastavat, mikä tarkoittaa myös sitä, että suomalainen betonitekniikka on laadullisesti hyvin korkealla tasolla. Tutkimuksen empiirinen osuus koostuu IoT-arkkitehtuurin rakentamisesta ja asentamisesta pilottityömaalle, sensorien datan keräämisestä, analyysistä ja talletuksesta sekä työmaahenkilöstölle tarkoitetun verkkopohjaisen applikaation kehittämisestä. Tutkimus osoittaa, että reaaliaikaisella kuivumisolosuhteiden seurannalla voidaan saavuttaa projektista riippuen hyvinkin merkittävää taloudellista hyötyä lyhentämällä rakennusvaiheen kestoa, tehostamalla lämmitysenergian käyttöä ja vähentämällä perinteisten kosteusmittausten määrää. Pilottiprojekti osoittaa, että työnjohto hyötyy selvästi applikaation käytöstä ja se auttaa ennen kaikkea nuoria ja vähemmän kokeneita työnjohtajia ymmärtämään työmaan rakennusfysiikan merkityksen betonin kuivumisprosessissa

Structural health monitoring of bridges using wireless sensor networks

Structural Health Monitoring, damage detection and localization of bridges using Wireless Sensor Networks (WSN) are studied in this thesis. The continuous monitoring of bridges to detect damage is a very useful tools for preventing unnecessary costly and emergent maintenance. The optimal design aims to maximize the lifetime of the system, the accuracy of the sensed data, and the system reliability, and to minimize the system cost and complexity Finite Element Analysis (FEA) is carried out using LUSAS Bridge Plus software to determine sensor locations and measurement types and effectively minimize the number of sensors, data for transmission, and volume of data for processing. In order to verify the computer simulation outputs and evaluate the proposed optimal design and algorithms, a WSN system mounted on a simple reinforced concrete frame model is employed in the lab. A series of tests are carried out on the reinforced concrete frame mounted on the shaking table in order to simulate the existing extreme loading condition. Experimental methods which are based on modal analysis under ambient vibrational excitation are often employed to detect structural damages of mechanical systems, many of such frequency domain methods as first step use a Fast Fourier Transform estimate of the Power Spectral Density (PSD) associated with the response of the system. In this study it is also shown that higher order statistical estimators such as Spectral Kurtosis (SK) and Sample to Model Ratio (SMR) may be successfully employed to more reliably discriminate the response of the system against the ambient noise and better identify and separate contributions from closely spaced individual modes. Subsequently, the identified modal parameters are used for damage detection and Structural Health Monitoring. To evaluate the preliminary results of the project\u27s prototype and quantify the current bridge response as well as demonstrate the ability of the SHM system to successfully perform on a bridge, the deployment of Wireless Sensor Networks in an existing highway bridge in Qatar is implemented. The proposed technique will eventually be applied to the new stadium that State of Qatar will build in preparation for the 2022 World Cup. This monitoring system will help permanently record the vibration levels reached in all substructures during each event to evaluate the actual health state of the stadiums. This offers the opportunity to detect potentially dangerous situations before they become critical

Augmenting the piezoelectric in portland cement paste for structural health monitoring applications

This report details the outcomes of a study designed to investigate the piezoelectric properties of Portland cement paste for its possible applications in structural health monitoring. Specifically, this study provides insights into the effects on piezoelectric properties of hardened cement paste from the application of an electric field during the curing process. As part of the reporting of this study, the state of the art in structural health monitoring is reviewed. In this study it is demonstrated that application of an electric field using a spatially-coarse array of electrodes to cure cement paste was not effective in increasing the magnitude of the piezoelectric coupling, but did increase repeatability of the piezoelectric response of the hardened material

Combined Punctual and Diffused Monitoring of Concrete Structures Based on Dielectric Measurements

This work presents a microwave reflectometry-based system for monitoring large concretestructures (during the curing process and also while the structure is in use), through the combineduse of punctual and diffused sensing elements. In particular, the adoption of punctual probes ona reference concrete specimen allows the development of an innovative and accurate calibrationprocedure, useful to obtain the value of the water content on a larger structure made of the samematerial. Additionally, a wire-like diffused sensing element can be permanently embedded inbuildings and used to monitor the structure along the entire length of the sensing element. Theadopted diffused sensing element can be used not only to detect dielectric variation during the curingprocess, but also throughout the service life of the structure. The combined use of punctual anddiffused sensing elements represents an important innovation from a procedural point of view, ableto provide detailed and quantitative information on the health status of the structure both duringand after construction

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Development of sensors and non-destructive techniques to determine the performance of coatings in construction

The primary objective of this work was to examine and develop techniques for monitoring the degradation of Organically Coated Steel (OCS) in-situ. This included the detection of changes associated with the weathering to both the organic coating and metallic substrate. Initially, a review of current promising techniques was carried out however many were found to be unsuitable for this application and the adaptation of current techniques and the development of new techniques was considered. A brief concept investigation, based on initial testing and considerations, was used to determine a number of sensing techniques to examine. These included embedded, Resonant Frequency Identification (RFID), Magnetic Flux Leakage (MFL) and dielectric sensing. Each of these techniques were assessed for the application, prototyped, and tested against a range of samples to determine the accuracy and sensitivity of degradation detection provided. A range of poorly and highly durable coated samples were used in conjunction with accelerated weathering testing for this aim. Track based electronic printed sensors were presented as both a cut edge corrosion tracking and coating capacitance measurement method. While suffering somewhat from electrical paint compatibility issues both concepts showed merit in initial trials however the capacitive sensor ultimately proved insufficiently responsive to coating changes. The embedded, progressive failure-based, cut edge corrosion sensor was produced and tested in modern coating systems with moderate success. Novel applications of RFID and MLF techniques were considered and proved capable of detecting large changes in substrate condition due to significant corrosion. However, there was a lack of sufficient sensitivity when considering early-stage corrosion of durable modern OCS products. Finally, it was shown that a chipless antenna could be designed and optimised for novelly monitoring the changes to the dielectric properties of a paint layer due to degradation. However, ultimately this test, due to equipment requirements, lent itself more to lab testing than in-situ. Due to some of these limitations a different approach was considered in which the environmental factors influencing degradation were examined with the aim of relating these to performance across a building. It was observed that a combination of high humidity and the build-up of aggressive natural deposits contributed to high degradation rates in sheltered regions, such as building eaves, where microclimates were created. The build-up of deposits and their effect was presented as a key degradation accelerant during in-use service. A unique numerical simulation approach was developed to predict the natural washing, via rain impact and characteristics of the building analysed. This approach showed promise for determining areas unlikely to be naturally washed, and therefore subjected to a degradation accelerating, build-up of deposits. Given these understandings coated wetness sensors were considered as a realistic live-monitoring device capable of determining deposit build up and ultimately OCS lifetime

Robotic installation of wireless strain gauges into precast concrete elements

This paper outlines our group's recent progress in the robotic deployment of wireless sensors within concrete precast elements. This study is focused on the automated installation of embedded vibrating wire strain gauges (VWSGs), interrogated by a wireless node. This paper outlines the initial development of our robotic process and the magnetic sensor packaging which is used to encapsulates wireless nodes and VWSGs. The system has been deployed onto an oiled metallic formwork, to simulate conditions found in precast factories. The magnetically attached sensor packaging can withstand loads imposed during the pouring of concrete and its vibration. The results of this pilot study are promising and could allow robotics to be successfully integrated into precast processes so that smart precast segments can be produced at scale