On growing concrete, walls that heal and walls that breath

I read this article the other day about a pair of Dutch scientists from Delft University that have developed self healing concrete. While concrete has become almost universal material of choice for construction, it has its set of challenges. My mind goes back to all the conversations I've had about earth construction and how earth walls breath and crack and all one needs to do is to add another coat of earth and one is good to go.

Coming back to the bio-concrete, the idea is quite elegant - they added a mixture of dormant bacteria and capsules of calcium lactate to the concrete mix. As cracks develop in the concrete due to weathering, the dormant bacteria come in contact with oxygen and water and spring to life. They ingest calcium lactate and produce calcite, which fills the cracks. 

I have my questions about the process. For example I don't know how they manage to keep the bacteria dormant during the preparation of  of concrete while the concrete mix is wet. The dormant bacteria will be in contact with moisture even when the concrete is setting - what will prevent it from producing calcite at that point? I'm not sure what is the mechanism being used but I'm sure they've figured it out because they're already testing it on the walls of a life guard station on a beach. Also because moisture is a necessary precursor for the self healing to kick in, the effectiveness of this material in hot and dry environments should be looked into.

This is kind of a 'living wall' is very different from the sense one uses for earth walls. Earth used in construction is of course teeming with bacterial (an other) life. Especially with uncompressed earth techniques, the thermal comfort and the plethora of life forms that live in it contribute to the effect that the walls literally breath. Do they heal themselves? Well I know there are a variety of additives added to mud plasters to avoid crack ranging from cow dung to husk to jute fibers and together they bind into structures that are resistant to crack. Active healing of course doesn't happen.

A little bit more digging on the self-healing concrete issue yielded another little nugget. This one also tries to fill the cracks as and when they appear but the approach is slightly different. A South Korean scientist from Yonsei University has developed a concrete coating that "contains polymer micro-capsules, filled with a solution that, when exposed to light, turns into a water-resistant solid. The idea is that damage to a coated concrete surface would cause the capsules to break open and release the solution, which then would fill the crack and solidify in sunlight." 

Where as all these solutions are very interesting, my concern is that the embodied energy of cement-concrete based construction is already quite high, these solutions may increase the life of concrete and reduce the energy required over the long term, but we don't know if the energy required to implement these solutions (especially the polymer based one) offsets the gains. Also these solutions are accessible to only a select few (one's with the technical know how and in future the ones with the paying capacity) and they don't depend on naturally occurring materials. This means that it will never be a truly democratic solution. I hope I'm  proven wrong there.