After maybe a week of temperatures continuously below freezing, day and night, my driveway raises well above the level of the garage's concrete.
The baking soda box is 2" high. The edge of the blacktop closest to the box is raised about 1.5"; about a foot further from the garage, the blacktop is maybe 2" high.
The house is on a slab. Soil in central NJ is somewhat heavy, but not clay-like. The whole property slopes gently down toward the street, which is 100 feet away. (According to Google Earth, the street end of the driveway is 3 feet lower than the garage end.) Behind the garage is a utility room. A little far-fetched that the water under the blacktop gets there by seeping from the back yard under the 28' slab to the start of the blacktop.
I have two good gutters taking roof water away from the blacktop. Each discharges its water at least 12 feet from the sides of the blacktop. One discharges its water about 25 feet closer to the street; the other discharges about where the blacktop meets the garage, but as I said 12 feet to one side.
The driveway is 10 years old. The old one, which was completely ripped out down to bare soil, also showed the same cold-weather behavior.
Even though it's only a cosmetic problem, and the blacktop will be level with the concrete once the weather warms, any ideas how to prevent this seasonal rise and fall?
Thanks,
R1