Green Sealant Joint
Here is one example of a green (but not sustainable) sealant joint that no owner will want on their facility. This joint was seen at a branch campus of a major university. It is located at the exterior terrace outside the main entry and lobby space for the conference center used by university and the general public - clearly visible to anyone using the facility. The terrace is subject to pedestrian traffic, only.
The joint failed, obviously. But joint sealants are not designed to withstand shear. They are designed to accommodate compression and extension occurring perpendicular to and in plane with the sealant bond line. Here the terrace concrete paving subsided by about 2 inches, probably due to poor substrate compaction. As a result the sealant failed both in cohesion at the top of the photo and adhesion at the bottom of the photo. Cohesive failure is identified by torn sealant material. Adhesive failure is identified by the sealant losing bond to the concrete substrate.
The greenery has no natural enemies in this location - no lawnmowers, weed whackers, or traffic. So it will continue to flourish until the joint is corrected or the maintenance staff finds some herbicide.
