Wouldnt the patio be stronger if I added cement into the cracks?
Actually, one of the benefits of using sand is that it allows the patio to flex with ground movement. When you place cement between the cracks of anything it becomes a single ridge slab that will crack due to ground movement. Also, if you had spilled cement over onto your pavers and didnt clean it off right away, it could permanently stain your pavers. So you would be sacrificing the flexibility and longevity of a mortarless system by placing cement between the pavers plus the possibility of staining them.
