Grouting

Micropile grouting is the final phase of execution, and is the most critical as it ensures the linking of the micropile to the surrounding ground.

CIMENTATEC uses a number of grouting systems, depending on the characteristics of the works. The most commonly used are as follows:

• Total injection (IGU). In this system, the grouting is performed in one single phase, introducing the grout or mortar to the interior of the tubular frame. This way, whilst the tube is being filled, the grouting fluid rises through the ring shaped gap from the base of the hole (inverse circulation), leaving the micropile perfectly cast at the end of the process. This type of grouting requires a minimum pressure of 5 kg/cm2.

• Repetitive injection (IR). In contrast to the previous case, IR grouting in completed in two phases. In the first phase the IGU system is used. During the second phase, a re-injection is performed, through a system of valves that can be fitted to the support tube of the micropile itself, or through special tubes equipped with valves, located just outside it. In this case the pressure required follows the same criteria as with IGU with a minimum of 5 kg/cm2.

• Repetitive selective injection (IRS). In this case, the micropile tubing is equipped with small hoses, spaced one metre apart, through which the selected grouting fluid is injected with the help of a double seal. Firstly, the selective grouting process is done, creating a seal in the circular gap between the pile ad the ground. This prevents the mixture from the later injection, completed at a higher pressure, from escaping. The selective injection process is completed in various phases (two or more) spaced in time so that each injection micro fractures the previous one and increases the “bulb” of the micropile. Increasing pressure is required for each phase, including pressures exceeding 10 kg/ cm2.