Spremljanje vlažnosti v kompozitih z mineralnim vezivom : diplomska naloga

Pristavec, Vid (author), Bokan-Bosiljkov, Violeta (mentor), Jagličić, Zvonko (co-mentor)

Cilj diplomske naloge je bil izdelati in preveriti delovanje sistema senzorjev, s pomočjo katerih bi lahko dolgoročno merili spreminjanje temperature in relativne vlažnosti v kompozitih z mineralnim vezivom. V sodelovanju s Fakulteto za elektrotehniko Univerze v Ljubljani, smo izdelali dokaj preprost merilni sistem, ki je sestavljen iz 8 senzorjev za merjenje temperature in relativne vlažnosti, sistema za sprejem in obdelavo signalov in sistema za napajanje ter prenos podatkov. V prvem delu naloge smo sestavili senzorje in preverili ali delujejo pravilno. Odločili smo se za uporabo senzorskih sond proizvajalca Sensirion, poimenovanih SHT 25. Gre za senzorje z digitalnim I2C vmesnikom, ki ponujajo dolgoročno stabilnost, komercialno dostopnost in sprejemljivo mersko napako. Okolje, v katero bodo senzorji vgrajeni, je zelo agresivno, zato so zaščiteni s posebnim pokrovom filtra in epoksi premazom. Vrednosti se beležijo in shranjujejo na računalniški enoti Raspberry Pi3. Odčitavanje in zapisovanje senzorskih podatkov deluje na podlagi treh napisanih skript, ki se izvršijo vsaki 2 minuti. Vzporedno uporabljamo komercialno poznan merili sistem Ahlborn ALMEMO, s pomočjo katerega na koncu preverjamo verodostojnost podatkov pridobljenih z našim sistemom senzorjev. V drugem delu smo pripravili recepture treh različnih mešanic in sicer : čista apnena malta, podaljšana cementna malta in lahki samozgoščevalni beton. Predhodno smo za namen preiskave pripravili tudi 8 opečnih zidakov. Mešanice smo zamešali po standardnem postopku in vanje vgradili senzorje. Pridobljene vrednosti temperature in relativne vlažnosti obeh merilnih sistemov smo analizirali in med seboj primerjali. Podrobneje smo obravnavali proces hidratacije in z njo povezano teoretično ozadje. S primerjanjem pridobljenih rezultatov meritev je bilo ugotovljeno, da izdelan senzorski sistem kljub zadovoljivemu delovanju potrebuje nekaj izboljšav. Primerjava rezultatov temperature je pokazala dobro delovanje sistema, večja odstopanja in slabše delovanje pa opazimo pri primerjavi rezultatov relativne vlažnosti. S pomočjo preiskave je bilo ugotovljeno, kakšne spremembe in izboljšave potrebujemo oz. bi želeli v procesu razvoja SHT merilnega sistema.

• Language: Slovenian
• Keywords: temperatura, relativna vlažnost, sistem senzorjev, merski sistem, hidratacija, hidratacijska toplota, mineralna veziva, kompozit, mešanice, gradbeništvo
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publisher: [V. Pristavec]
• Year: 2020
• PID: 20.500.12556/RUL-114358
• UDC: 691(043.2)
• COBISS.SI-ID: 15947779
• Publication date in RUL: 22.02.2020

Secondary language

• Language: English
• Title: Humidity control in composites with mineral binder : graduation thesis

Abstract

The purpose of the diploma thesis was to design and test the functioning of a sensor system, which could be used for long term measurements of the temperature and relative humidity in mineral binder composites. In a cooperation with the Faculty of Electrical Engineering University of Ljubljana, we have developed a fairly simple measuring system consisting of 8 sensors for measuring temperature and relative humidity, a system for receiving and processing signals, a power supply system and data transmission system. In the first part of the thesis we assembled the sensors and checked if they are working properly. We decided to use Sensirion sensor probes, named SHT 25. These sensors are using a digital I2C interface and are offering long-term stability, commercial accessibility and acceptable measurement errors. The environment in which the sensors will be integrated is very aggressive, so sensors have been protected with a special filter cover and epoxy coating all over the sensors. All the values sensors recorded were stored on a Raspberry Pi3 computer unit. All the sensor data readings and recordings works on the basis of three written programs, which are executed every 2 minutes. To compare all the received values with SHT sensor system we used commercially well known sensor system Ahlborn ALMEMO. In the second part of the thesis we prepared three different mixtures: pure lime mortar, cement – lime mortar and lightweight self – compacting concrete. We also prepared 8 brick units. All the mixtures were mixed by standard procedure and the sensors were installed inside them. All the obtained values of temperature and relative humidity of both sensor system were analysed and compared with each other. We discussed the hydration process and its theoretical background in more details. By comparing all the obtained results we found that despite satisfying performance, the sensor system needs some improvements. Worse performance were observed when comparing relative humidity results. Within investigation we identified which changes and improvements are needed or can be done within the measurement system development.

• Keywords: temperature, relative humidity, sensor system, measurement system, hydration, hydration heat, mineral binders, composite, mixtures, civil engineering