repairing horizontal cracks in a stem-wall foundation
The above video shows one way to repair horizontal cracks in stem walls. The procedure is exactly the same as for horizontal cracks in perimeter grade beams in slab-on-ground foundations.
What causes horizontal cracks
Horizontal cracks in stem wall foundations and in slab-ground-foundations are caused by the rebar being attacked by moisture penetrating through the concrete. Many people are not aware that water can penetrate concrete it.
Once moisture reaches the rebar it will begin to rust. When steel rusts, it grows in volume, at least initially. The steel grows in volume by around 500%. Long before the rebar grows by 500%, it will fracture the concrete creating horizontal cracking. When the cracking begins, more moisture will reach the steel in a vicious cycle.
If no effective repair is made, the stiffness of the affected beams will be compromised.