We will discuss about general grout compositions for mud jacking in this post. The mudjacking procedure and grouting pressure for different conditions of mudjacking will be discussed in the posts. For a successful mudjacking for slab foundations, grout consistency and its composition is very important. In the previous post we discussed about the consistency to containment relationship of grout and way of containment of grout in extreme conditions.
Typical compressive strengths of grout, designed in mud jacking are 50 psi(345 kpa) to 100psi(690 kpa). For these compressive strength 376 lb cement(two sacks), 1800 lb siliceous soil and water of 70 gal/yd3 of dry mix is enough. This mix is known as two sack grout mix. Two sack grout mix is used in general mudjacking operations. This composition produce sufficient strength with flowing facilities if provided grout is not watered down. The composition also controls shrinkage. The applied grout, when set, provides suitable conditions for excavation and reentry of it if required.
When an increased strength is required to achieve, a four sack mix can be used. This thicker grout has a compressive strength of 400 psi approximately. This is to note that, the compressive strength should be calculated at 28 days.
In case of grouting application in dam a neat cement grout is used having compressive strength of 8295 psi (28 days). The water requirement should of 5 gal/sack.