This paper investigates the application of a vacuum techinque for preconditioning concrete in situ prior to permeation tests. Cover concrete absorption test (CAT) and Figg Air permeation index test (API) were applied after vacuum drying of concrete. the application of Vacuum using ISAT cap did not lead to satisfactory of the results with these tests. However, direct application of vacuum to CAT and API heads prior to testing resulted in improvement of reproducibilty of the permeation indices obtained from these tests.