Description

Jet grouting is a ground improvement or soil stabilization method. Methods, procedures, applications and advantages of jet grouting is discussed in this article.
1.    Base Grouting
Base grouting is becoming more widely promoted in the drilled shaft industry as a means to improve shaft response to load. There area limited number of full-scale field comparisons of test shafts which have been base grouted and adjacent test shafts which have not.
This paper presents several case histories of full-scale static load test shafts as well as the results of the tests conducted on adjacent shafts with and without base grouting. The paper compares six pairs of adjacent grouted and ungrouted shafts on 5 separate projects
in various parts of the United States. All tests were performed using the Osterberg cell (O-cell) test method. The comparisons yielded some intriguing results. In some cases the results matched theory quite well and showed some improvement to stiffness and overall
capacity. In other cases this was not the case. Among other conclusions, the paper illustrates the need for further load testing and research to better understanding how drilled shaft capacity is affected by base grouting, particularly how the capacity is affected by technique, methods and quality control in various materials.
2.    Shaft grouting
In shaft grouting operation, tube-a-manchette pipes are fixed at regular spacing to the reinforcement cage. After concreting barrettes/bored piles, a small volume of water is injected under high pressure into these pipes to crack the concrete.
The cracking process should be carried out within 24 hours after concreting. The purpose of cracking is to create a path for grout to go through. About a week after concreting of barrette, grouting is then carried out in these pipes to improve the friction between the foundation and the surrounding soils.
3.    Cement Deep Mixing
CDM (Cement Deep Mixing) Method uses cement-base solidifier slurry to be stirred and mixed with soft soil by a treatment mixing equipment to improve the strength of soft ground to a specified level in its natural position.
The strength of treated soil is increased by hydration reaction of cement-base solidifier and water and by pozzolanic reaction of calcium hydroxide produced by hydration reaction and cohesive soil.