Interior Slab Repair Debate - Which repair option is best?
We are often asked which is better - Polyurethane (poly) foam injection (or mudjacking) or deep compaction grouting?
Polyurethane injection is about 5-8 times cheaper than compaction grouting.
The answer requires some explanation of various conditions. Generally polyurethane injection is about 5-8 times cheaper than compaction grouting, however it does not improve the soil below, rather it is a surface treatment. Though one should not look at cost alone when making a repair plan decision.
How are polyurethane injections used in a foundation repair?
To better explain how polyurethane injections are used in a foundation repair, let's take a look at the diagrams below:
The above shows a typical foundation settlement dynamic. Note that the reason for the slab settlement is rooted in the footing settlement because of the void space, illustrated in the diagram below.
In other applications, such as basement backfill zones, or other deeper soil problems without the benefit of the footing slab interaction, poly injection presents a less confident solution as it does not improve soil conditions but rather only raises the slab to a more desirable elevation.
Even in these applications it may still make sense to select it over compaction grouting since it can be reinstalled, several times, for less than the cost of compaction grouting... no, really. The deciding factor is usually things like downtime, inconvenience, avoiding multiple repairs to floor finishes and other similar reasons.
Polyurethane injections are a cost effective way to level a concrete slab.
Both compaction grouting and poly /mudjacking injections have valid arguments for use depending on circumstances and site conditions. Basically, like any other foundation repair, we need to look at the full picture before deciding on a repair plan route.
For more information about Concrete Repair, click HERE. See my blog for a discussion of poly as soil improvement: http://www.foundationaz.com/blog/grouting-smoke-and-mirrors-part-I.html and http://www.foundationaz.com/blog/grouting-smoke-and-mirrors-part-ii.html
