The modifications have been made prior to this weekend's race on the track's outer circuit, which includes the area where Grosjean crashed on the exit of Turn 3.
The most significant change is the addition of tyres and a conveyor belt to the barrier that the Frenchman's Haas made contact with, greatly reducing the chances of a repeat of the sort of impact that he suffered.
The concrete blocks which were put in place for the race restart after the damaged section was removed have been replaced with new steel barriers.
There have also been changes to Turn 9 of the outer circuit – which in effect is a much faster version of Turn 13 on the standard track.
A kerb prior to Turn 9 has also been removed because of concerns about a car getting airborne.
Such changes are not made lightly as they have an effect on the FIA homologation of the circuit, but procedures exist for them to be made should circumstances require.
The FIA noted: "Following a review of the recent Bahrain FIA Formula One World Championship event with the FIA F1 Race Director, the FIA Circuit Inspector and the FIA Safety Department, the following changes will be made to the Bahrain International Outer Circuit in advance of this weekend's forthcoming Sakhir Grand Prix.
"Two rows of tyres with conveyor belt will be installed on the right hand side between T3 and T4.
"The tyre barrier on the right hand side of T9 will be extended and increased in depth to four rows of tyres with conveyor belt
The right hand kerb between T8 and T9 will be removed to reduce the risk of a car becoming airborne while the outer circuit layout is being used.
"These changes are in accordance with Article 5 of the FIA Circuit Licence conditions of issue, and as such the current FIA Grade 1 licence for all configurations of Bahrain International circuit remains valid."