There are 6 Tech Buildings in Yuri's Revenge, 3 of which were also in the original Red Alert 2. Tech buildings provide different services/options to the player when the player captures them with an engineer.
The tech hospital was in the original, however it has been upgraded for Yuri's Revenge. When captured it will automatically heal any infantry units, regardless of their position on the map. An important tech building to capture - especially if you use infantry a lot.
Tech Machine Shop
This is a lot like the tech hospital, apart from it auto-repairs any vehicles on the map instead of infantry. Again it is an important tech building, this may just give you the edge in long tank battles!
This tech building returns from the original, unchanged. When captured it will give you paratroopers, this take about 5 minutes to charge and then you can drop 6 infantry units (Soviets = Conscripts, Allies = GIs & Yuri = Initiates).
Secret Tech Lab
If you capture this building you will be given the ability to create a special unit that you are not normally able to build. You may gain the opportunity to build Allied, Soviet, or even Yuri units regardless of the army you are leading.
Tech Oil Derrick
The most important tech building returns unchanged from the original. When captured it gives you a steady flow of money. If you are the first to capture the derrick it will give you a bonus of £1000. One can give you the edge in a close battle, many will win the battle for you.
Civilian Power Plant
Civilian power plants are similar to the power plants created by each of the different factions. Capturing one will significantly increase your current power supply. This are quite rare and I have only ever found them in the single player missions.