Biyogranül İçeren Mikrobiyal Kendini Onaran Betonların Aralıklı Islak/Kuru Döngülerde Kendini Onarma Performansı

Beton yapıların bakımına yönelik olarak yürütülen ve yoğun iş gücü isteyen izleme/onarım faaliyetlerinin minimuma indirilebilmesi için, kendini algılayan ve kendini onaran betonların geliştirilmesi önem arz etmektedir. Kendini onaran betonların bir çeşidi beton çatlakları içerisinde kalsiyum karbonat çökelmesini tetikleyen mikrobiyal ajanların kullanılması ile elde edilebilir. Son zamanlarda, nitrat indirgeyen mikroorganizmalardan oluşan biyogranüller yeni nesil mikrobiyal ajanlar olarak sunulmuş ve biyogranül içeren numuneler batık koşullarda iyi bir çatlak onarım performansı göstermiştir. Ancak, bu numunelerin çeşitli beton yapıların maruz kaldığı aralıklı ıslanma koşulları altında performansları bilinmemektedir. Bu çalışmada, biyogranül içeren mikrobiyal harç örneklerinin aralıklı ıslak/kuru koşullar altında kendini onarma performansları sunulmaktadır. Kurum içinde üretilen biyogranüller harç numunelerine çimento ağırlığınca %1.45 w/w (% 1.00 bakteri w/w çimento) dozunda eklenmiş ve çatlatılan harç numunelerindeki 50 ila 600 µm arasındaki çatlakların birbirini izleyen ıslak/kuru şartlarda kendiliğinden iyileşme performansları incelenmiştir. Islak/kuru döngülü 4 haftanın sonunda, biyoharç numunelerinde 400 µm genişliğine kadar olan çatlaklar etkili bir şekilde iyileşmiştir. Daha iyi kendini onarma performansları sayesinde biyoharç numunelerinin su sızdırmazlık geri kazanımı kontrol numunelerine göre %44 daha fazla gerçekleşmiştir. Genel olarak, biyogranüllerin püskürme veya aralıklı ıslanma koşullarına maruz kalan yapılarda uygulanmaya yönelik olarak geliştirilebilecek kendini onaran biyobetonlar için kullanışlı olduğu görülmüştür.

Self-healing performance of biogranule containing microbial self-healing concrete under intermittent wet/dry cycles

Development of self-sensing and self-healing concrete is essential to minimize the labour-intensive monitoring and repair activitiesconducted for the maintenance of concrete structures. A type of self-healing concrete can be achieved by using microbial agentsthat induce calcium carbonate precipitation inside a concrete crack. Recently, biogranules consist of nitrate reducingmicroorganisms were presented as a new generation microbial healing agent and biogranule containing specimens revealed decenthealing performance under completely submerged conditions. However, their performance under intermittent wetting conditions,a common case for various concrete structures, remains unknown. This study presents the self-healing performance of biogranulecontaining biomortar specimens under intermittent wet/dry conditions. In-house produced biogranules were incorporated intomortar specimens at a dose of 1.45% w/w cement (1.00% of bacteria w/w cement) and self-healing performance of crackedspecimens were investigated under alternating wet/dry conditions for a crack width range of 50 to 600 µm. Upon alternating wet/drytreatment for 4 weeks, cracks up to a 400 µm crack width were effectively healed in biomortar specimens. Their water tightnessregain was 44% better than control specimens due to their enhanced healing performance. Overall, non-axenic biogranules appearto be useful in development of self-healing bioconcrete for applications under spraying or intermittent wetting conditions.

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