In this study, stirring speeds during the synthesizing process of the sodium silicate/polyurethane microcapsules were optimized. The yield values of microcapsules at different stirring rates were evaluated. Based on the yield values and shape of microcapsules, optimized microcapsules were obtained. The measurements of the shell thickness of microcapsules were performed on the fractured microcapsules by using scanning electron microscopy. The optimized microcapsules were further characterized by means of optical microscopy and nanoindentation. Load vs. displacement and modulus of elasticity vs. displacement characteristics of the microcapsules were obtained. The average modulus of elasticity was found to be 633 MPa. The self-healing efficiency of the optimized microcapsules was evaluated by means of compressive strength tests. The incorporation of microcapsules reduced the compressive strength of fiber-reinforced mortar by 12–22%. However, it was observed that the microcapsules enhanced the self-healing capacity (recovery in compressive strength) of the mortar.

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In this study, it was aimed to produce a four-person lightweight concrete canoe to participate in the National Intercollegiate Concrete Canoe Competition organized by Istanbul Technical University. Concrete canoe competition is a prestigious activity held regularly in the USA since 1988 by ASCE, mainly aimed at sharing knowledge among civil engineering students. For this purpose, two lightweight concrete mixtures with a hardened unit weight lower than 1000 kg/m3 were designed. Despite of such a low hardened unit weight, they have 13 MPa and 18 MPa compressive strength with excellent bond properties with basalt mesh reinforcement. A nonlinear finite element model for concrete canoe was generated to determine the moment capacity in such a way that four rowers could row at the same time, taking into account the competition rules.@en