Use a jacking pump and raise the concrete slab to about six inches or the level you want for repair. If you can not do it yourself, you can hire professional lifters or jacks.

Before you pour a concrete slab, you need to consider the place of pouring. If not well organized, use a skip loader or backhoe that will help scrape off the available organic materials on the topsoil.

Use a mudjacking technology where you need to drill a hole or several holes on the sunken concrete section (each hole to be 2 inches in diameter). Inject a slurry of cement, sand, and water with much pressure through the drilled holes. In the process, the slurry lifts the concrete as it hardens underneath.

Dig holes sideways of the sunken concrete until the base of the slap is seen. Hold the slap with an eight-inch c-clamp on both ends. Then use a strong metal strut and cross it to reach the clamp; attach the ends of the metal strut and the clamps with a strong chain. Place one on each end of the metal strut using two car jacks. As you lift your car with a jack, pull up the metal strut on both sides with the carjacks simultaneously to the level required or leave space to fill up with slurry.