The investigation of stress and temperature behaviours of the smart lightweight concrete

ABSTRACTPhD ThesisTHE INVESTIGATION OF STRESS AND TEMPERATURE BEHAVIOURS OF THESMART LIGHTWEIGHT CONCRETEBahar DEMİRELFırat UniversityGraduate School of Natural and Applied SciencesDepartment of Construction Education2006, Page :95In this thesis, the reactions of the carbon fiber reinforced lightweight concrete, whosematrix was formed by pumice aggregate, in response to the external forcing such as stress andtemperature were investigated. With this study, it was also aimed to evaluate pumice, which is anatural material in the region, by using as aggregate in concrete.In the study, the concrete was made smart by adding short conductive carbon fibers andits sensing ability of strain and temperature was investigated by observing the change on theelectrical conductivity under the compression, tension and temperature differences. In addition,the changes that mineral admixtures such as fly ash and silica fume constituted on the self-sensing ability of the smart lightweight concrete were investigated. Compressive and tensiletests were applied to the samples prepared for this study and electrical conductivity change wasobserved by applying the static and cycling loading.Microstructures of the samples and fractured surfaces were examined by SEM(Scanning Electron Microscope) thus determining structural properties and changes affectingthe sensing ability of concrete. In addition, it was shown that carbon fiber reinforced lightweightconcrete was a smart material that could sense not only compressive or tensile stress, but alsotemperature differences by the aid of Seebeck coefficient calculated.The thesis consists of 7 Chapters. In the first chapter, the topic of thesis is explained in ageneral frame and the aim of the study is clarified shortly. In the second chapter the commonmaterial of the structures, concrete, is dealt with in general. In the third chapter, the fundamentalchapters such as how smartness occurs in structures, smart materials and concrete, functionalprinciple of smart concrete and the places where smart concrete are used are given. Literatureresearch and the place of the thesis in the literature are given in chapter 4 in detail. The 5thchapter comprises experimental studies, materials and methods whereas in the 6th chapter resultsand discussions are presented. In the last chapter, conclusions and recommendations take place.As a result, it was seen that carbon fiber reinforced lightweight concrete had the abilityof smartness which has not been investigated so far. Therefore, it was concluded thatdeformation and damage due to the stress and temperature could be sensed in lightweightconcrete.Keywords: Smart Lightweight Concrete, Sensing Ability, Carbon Fiber, Fly Ash, SilicaFume