Acceleration
Speeding up the works to recover delay — overtime, extra shifts, additional crews, resequencing. Instructed acceleration is paid for. Constructive acceleration, where an EOT was owed and refused, is a claim you have to build.
Constructive acceleration is the version that produces disputes. The contractor is entitled to an extension of time, is refused it, and accelerates anyway to avoid liquidated damages that should never have applied. The cost of that acceleration is recoverable in principle — but only if the entitlement to the EOT can be demonstrated, and the refusal, and the fact that acceleration followed from it.
Which means the records that would have won the EOT are the same records that win the acceleration claim. There is no separate evidential route. If the notice was late or the programme was not maintained, both claims fail together.