to NGA
A conversation I used to have with my mother in law:
Me: What is that?
Her: Its a Yuzu
Me: Is that a lemon?
Her: No, its a Yuzu
Its a Yuzu. Not a lemon in sight.
On to your question: The foliage discoloration suggests to me that your plant is lacking in some nutrient or another. Concrete is a base and citrus are acid loving plants. The dust could have altered the Ph of your potting soil thereby making the nutrients in your soil unavailable to your plant. Your tree needs some fertilizer that's acidic. Find some fertilizer specifically formulated for acid loving plants.
