A Brief Explanation of Compaction Grouting

Compaction grouting (pressure grouting) is a way to consolidate foundation soil by injecting grout into it. This process is used to stabilize structures which have settled and to improve the ground underneath new construction before it begins.

An analysis of the ground is made and plans are drawn up. Then a series of grout injection pipes are installed to the required depth by either drilling or driving them using a sacrificial point. They are usually placed in a grid pattern in either as little as 6-feet and up to 12-feet. The depth of the holes depends on the demands of the project, but grouting can be injected up to 80-feet below ground.

Construction crews start from the perimeter work their way inward, injecting a low slump grout with a low volume, high pressure pump. They fill the hole in stages. The pipe is withdrawn at a controlled rate (a few feet at a time) to give the grout a globular shape. The grout is injected until a predetermined pressure is reached or the ground begins to heave upward.

When all of the holes are filled, the ground will be more stable and you can begin your construction with the peace of mind that your foundation will not collapse on you. This entire process can also be used in combination with underpinning to raise a sunken home.

Do not attempt to follow these steps yourself. They are just an overview of a complex process. It is important that you contract with a fully licensed and bonded professional who specializes in this type of work. This method of soil consolidation is a costly and sometimes risky procedure, especially if you don’t know what you are doing. It requires equipment specially designed.

Soil consolidation refers to the process of decreasing soil by volume. In our application, that is usually done by first compressing the soil with heavy equipment (like a roller). When pressure, or stress, is applied to the soil, it causes the particles to squeeze together tightly, reducing the volume and creating a more stable foundation.

If that pressure is lessened or removed, the soil will rebound and regain some of its volume. Rebound can be caused by a variety of factors, including water absorption. Compaction grouting will fill any voids and reapply pressure to the soil so that it stays more compact. If you would like to find out if compaction grouting is the solution to your problems, contact a local company to have an analysis completed.