Structural rehabilitation of damaged concrete structures often calls for injection of specified grouting material inside concrete core. This injection is always done with specified pressure. How important that pressure is?

It is indeed very important.

When an under-pressure activity is to be taken up, its necessity is to be properly addressed. Injection method is to be sought for only under special situations where other methods are not found effective. Injection operation under pressure is a blind work. One won’t know the path followed by the material being injected although it would have a reason for its selection based on observations and results of non destructive testing. This calls for its meticulous execution at field so that the activity happening beyond our vision, happens to the benefit of the damaged structure.

Pressure at which the grout is to be injected within the core concrete must be very precise and optimum. It should be just adequate for the grout (with its known viscosity) to reach and to plug the crevice of the core concrete mass. It should also be not very high for pushing the grout for plugging the crevice because if it is higher than required, it would exert additional pressure on the walls of crevices as a result of which the crevices would expand before getting plugged. Of course the crevices would be plugged during the injection process but (as said earlier,) it may create the stresses due to excessive pressure in that case through the crevices which might add a new dimension to the damage.

Always be careful while carrying out injection operation to rehabilitate the damaged concrete members.