Two small commercial buildings have been constructed at a site under lain by a sandy silt (ML) that has D₁₀ = 0.03 mm. The groundwater table is at a depth of 6ft. Both buildings have concrete slab-on-grade floors. In Building A, the slab was placed directly onto the natural soils, while Building B has a 4-inch layer of poorly- graded coarse gravel between the slab and the natural soils. Both buildings have vinyl floor coverings similar to those typically used in residential kitchens. Both buildings are now three years old.

Unfortunately, the tenant in Building A is having continual problems with the vinyl floors peeling up from the concrete slab. When the peeled sections are examined, moisture is always evident between the vinyl and the concrete. Curiously, the tenant in Building B has had no such problems, even though both buildings have the same floor covering. Could the problem in Building A be due to capillary action in the underlying soil? Explain why or why not. Also explain why Building B is not having any such problems.