In my thesis I included some pages of a foreign specification. To improve the reader's convenience I have translated them as they are vital to my topic and I can't paraphrase them.
How do I properly cite these five pages/mark them as not my own?
If this section of the thesis contains only the translated passage, then it is silly to use one of the quotation notifiers. As I said in my comment, preface the whole section with a notice about the origin of the passage. Then, present the passage unaltered (except for the translation). The contents of that notice will depend on which of the following categories the original passage falls into:
The original passage is in the public domain (for example if it was written by a government employee in the course of their normal duties or if the author released into the public domain or if the passage is old enough that any possible copyright has expired) - then say something like
The following section is was translated by (your initials) and is reproduced without any further alterations from (original source). This passage is in the public domain (rationale if possible).
Since a thesis is a document created in the course of obtaining an education, you can claim fair use for educational purposes. The passage represents less than the fair use maximum set for the original document (typically around 5% or less of the original work), then you can state something like
The following section is was translated by (your initials) and is reproduced without permission and without any further alterations from (original source). Since this passage represents a minimal part of the original document, it constitutes fair use.
The creator of the document could have released the document under a license that allows reuse for non-profit purposes with appropriate attribution. See Creative Commons Licenses and GNU General Public Licenses. Licenses like these generally allow you to reproduce the work if you include the appropriate statement. Make sure the license allows derivative works (because that is what your translation is).
The following section is was translated by (your initials). It is reproduced from (original source) under the Creative Cmmons Attribution-NonCommercial-NoDerivs 3.0 Unported (CC BY-NC-ND 3.0) License. The original copyright is held by, and all other rights are reserved by, (original copyright holder).
If you have obtained written permission from the copyright holder to reproduce the work in your thesis, then you would state something like the following. You should include the evidence of written permission in your appendix.
The following section is was translated by (your initials). It is reproduced from (original source) with permission of the copyright holder. The original copyright is held by, and all other rights are reserved by, (original copyright holder).
None of the above
Without permission, a license, fair use, or public domain, you are violating copyright by reproducing the passage, even if you translated it (translations count as derivative works, which are still a no-no). Get the appropriate permissions or reduce the length of the passage so that it becomes fair use and see above.
Note that this answer primarily to US Copyright Law, with which I am most familiar. The copyright laws in other nations, as well as international copyright law, will vary, but many have similar provisions. However, some parts of my answer will be inapplicable in some countries. In these cases, behave as if the material is copyrighted. The concepts of public domain, copyright, and license are fairly similar in most places. Generally, the existence of a license supersedes copyright, with the exception that a license cannot supersede the public domain status of a work. Fair use may not exist in all jurisdictions. If you are unsure whether your nation has a fair use or similar exception in its copyright law, act as if it doesn't. Better safe than sorry.