Detection of the alkali-silica-reaction in geopolymer and cement-based structures by using a new electrically small metamaterial-like microwave sensor

Portland type of cement-based materials are widely used in the building industry. Some aggregates that host (e. g. Rhyolite), certain silica minerals in these materials (Opal, Obsidian, Cristobalite, Tridymite, etc.) and the reactive minerals (Na and K) in the alkaline hydroxides constitute the alkaline silica reaction (ASR). On the other hand, when the reaction products of geopolymer structures, which are an alternative to Portland type cement-based materials and are environmentally friendly (less CO2 emissions), reach the maximum, the alkalis remaining in the concrete void solution become more unusable and, in this case, the unused alkalis react with the reactive silicas in the aggregates to form ASR. One of the most important parameters affecting ASR is water. Since the dielectric coefficients of free and bound molecules of water are very different from each other at microwave frequencies (~300 MHz-30 GHz), it is thought that non-destructive microwave techniques are more advantageous than other non-destructive methods (expansion measurement method and seismic-wave methods) in detecting ASR formation. In the proposed thesis, our primary aim is to determine the ASR in cement-based and geopolymer materials (via correlations) with non-destructive microwave metamaterial (MM) sensors containing new generation resonance cells for the first time in the literature. Our second aim in the thesis is to develop a general new line-to-line method that will eliminate the effects of SMA connection errors in the determination of ASR formation with (a) symmetric reflection- and transmission-resonant microstrip line MM sensors. The final aim of the thesis is to determine the amount of ASR and to analyze the water reaction mechanisms and phase transitions in geopolymer structures.