Jet mixing and jet grouting are terms that go hand in hand. These procedures involve using high streams of pressurized grout to mix, replace, erode or cement soil. Rising, rotating and mixing drills are used. They create cemented columns of soil and concrete, which are often called soilcrete. Jet grouting is the only effective way to treat all types of soil. There are several different techniques for creating jet grout columns.
Deep Soil Mixing
DSM treatments involve blending reagent soil elements and cement to strengthen the ground and reduce compression. This technique is used for soft soils that need more stability and less settlement. However, this technique has also been used to treat soil that has been contaminated. Augers, blenders, road re-claimers and backhoes may be used for soil that has not been excavated. Pugmills may be used to mix materials that have been excavated.
This technique uses a binder to break and mix the soil. High pressure is used to initiate the binder, drill strings and nozzle. This system requires a special drill string that controls rising and a batching plant with enough capacity for the grouting binder. The rotary method creates a borehole, and a flushing medium is used. Compressed air, water, a binder and bentonite are common mediums.
This technique differs from the monofluid system by using a high-energy water jet instead of a binder for breaking soil. In addition to the water injected, compressed air is used. The air widens the water jet's radius of influence. Over time, the mixture sets to yield a stabilized column. It is usually about two meters or slightly thicker. The main difference in results between this technique and the monofluid system is the amount of treated soil per hole, which is directly related to the diameter of each stabilized column. Since fewer holes are required, the three-fluid system is best for soil that is hard to drill. The only downside is that this system requires more equipment and is much more complex.
This is a newer system, and it combines the monofluid and three-fluid techniques. Its main basis rests upon the monofluid system's principles. However, it uses a compressed air aureole to enhance the radius of the columns. By adding the air component, a column's diameter can be increased by one inch. With the exception of an air compressor and a two-way coaxial drill string, the equipment requirements are the same as the monofluid system's requirements.