I have an image of your garage as a bunker-like structure with concrete walls on three sides and apoured ceiling / patio area. Repairing a bunker is a new experience for me; however, in terms of sealingthe concrete for your roof/patio this should be pretty straightforward.
Repairing the cracked concrete
Here is a great video that explains which product to use and how to seal each of the cracks which willsave me from typing out instructions!
This should address the cracks you have on your patio and prevent future erosion from theelements and water from leaking into the garage.
Sealing the concrete
The next step is to seal the concrete either with a clear or colored concrete coating but let's address thetopic of a "green sealant" first.
The greatest danger with a concrete sealant would be the impact on airquality in the form of volatile organic compounds. Since your project is outside you have many moreoptions in that regard.
- Typically I would advise clients to use a low VOC sealant such as Scofield SelectSeal W which meets the USGBC's LEED for Homes Criteria for VOC usage in an area such as an attachedgarage slab.
- Since your patio is outdoors the VOC limitations are not as stringent.
- There are severaloptions available on Schofield's site here.
Be sure tocheck the data sheet on the product you use to seal the concrete to ensure it will work well with thematerial you used to fill the cracks!
Covering the patio
If you are not interested in a color option and don't like the look of your patio after you've sealed it witha clear sealant, you have the option of covering the patio with a wood floor look.
- There is a productmanufactured by an FSC certified organization that can beautify your patio after you've filled thecracks and sealed the concrete.
- Have a look at Decktiles.org for a magnificent finish to yourproject.
For more information:
Read "I need to stain my concrete pool deck. Are there products and methods you can recommend, other than acid?" a Q&A answered by Cynthia Phakos.