A good slump height really depends on the project, but there is a use for nearly all slump levels. For example, low slumps are best in projects that require structure, such as curbs and roads. High slumps often require additional reinforcement, but they flow more freely into hard-to-reach spaces.

Mudjacking typically takes 24 to 72 hours (one to three days) to dry and cure completely before you can resume normal use. The total drying time can vary depending on the size of the project. Because the slurry mixture contains cement, it needs to harden fully to prevent the concrete slab from shifting under added weight. You should avoid walking on the concrete or placing heavy items like furniture or vehicles on the surface until it has fully set. Your concrete contractor can provide a precise timeline. As a point of comparison, if you opt for polyjacking, the polyurethane foam can dry in minutes, but it's recommended to wait about an hour before use.

A sinking foundation can be lifted, most often by installing piers to re-level and support the weight of the house. Depending on the cause and extent of the sinking, other methods to lift a foundation include underpinning and mudjacking. Consult a foundation repair pro to determine the best way to lift your sinking foundation. 

Most projects take 1-3 hours, with immediate usability after completion.