Team:SZU-China
SZU-China
Concrete Self-repair
The project of SZU-China this year is Concrete Self-repair. Along with the development of science and technology, more communication from place to place is required. Thus more and more cross-sea bridges, undersea tunnels were built. These bridges and tunnels are built under extremely strict requirements, yet there still are multiple reasons that can cause damage to the structure. Such as ocean current, sea water corrosion, marine organism. Once these bridges are put into use, it will be really inconvenient to repair the undersea part of the structure and will cause much trouble for the residents while doing it. Conventional methods which used to protect the bridges for example, protective coating, cathode protection, can only prevent microfractures appear in a certain level. But none of them can fill up or fix the inevitable microfracture after it appears. Thus this year SZU-China will fix this in a synthetic biological way.
We wish our device only starts to work when the microfracture appears and stay silent before that. So we make our device into a capsule containing our transgenic Bacillus subtilis spores which are given the ability to produce calcium carbonates after germination, and the culture media powders for them to function. GerA gene which we choose to transfer in our Bacillus subtilis will be the receptor and the start switch of the whole process. When the microfracture appears, it will tear the capsule open and seawater will enter. This is where our cell membrane receptor GerA works. When the sea water comes in, our powder culture media will liquefy and the GerA will receive the signal from liquid germinants L-alanine and start the germination of the spores. We also transfer CA-enzyme gene into our Bacillus subtilis so that they will have the ability to fetch CO2 and H2O and make them into CO₃²﹣. When CO₃²﹣combine with the Ca2+ we add in our culture media, there will be precipitation of calcium carbonates which can fill the microfracture in the bridges in order to prevent them from expanding to bigger cracks. This way we can greatly prolong the life of these bridges. After considering the harsh environment our bacteria will be stay in, we also add nhaC, which is an Alkali resistance gene to improve the environmental stress-tolerance.
When microfracture appears and our system being switched on. our transgenic Bacillus subtilis will be able to help the concrete self-repair its microfracture in order to prolong the life of the Cross-sea bridges, under sea tunnels and so on.
