Concrete structures, while they may seem invincible, are actually subject to a wide variety of environmental stresses – many of which can cause damage such as cracks, heaving, or even sinking. Once settlement begins, the damage almost always gets worse as time goes on, and the soil beneath the structure continues to erode.
Once you’ve decided that you want to repair, rather than go for a full-on replacement, you need to consider which method is best. Mud-jacking (also commonly known as slab jacking and pressure grouting) is a well-known tried and tested solution for lifting sunken and uneven concrete slabs. However, thanks to recent technology, polyurethane injections are also becoming a common alternative solution. So which method is the best? Here are some advantages and disadvantages of both to help you make up your mind.
Mud-jacking is a commonly used method to raise sunken concrete, raising slabs by pumping grout through it. Water is combined with a dense limestone aggregate and injected into drilled holes to fill any spaces that have been created as a result of soil compaction or water erosion. Once the areas are successfully filled, the concrete slab is pushed back up from below.
The injection uses a closed-cell polymer foam that seals gas pockets to prevent any water from being soaked up. The material is injected via a hole, with the foam passing into, through and below the concrete block. Once the foam reaches beneath the slab, the reaction between the expansion of bubbles in the foam lifts the block back up.