It depends on how you define 'loose'. What are the stresses? For that matter, what is 'loose cohesive soil': cohesive soil isn't usually characterised by its density (that's for cohesionless soil).
Whether or not something will contract or dilate depends on what side of the critical state line you are. Generally you wouldn't expect 'loose' soil to dilate, but the stresses and critical state line are the other factors to consider.
Just as precation, are you installing driven piles? Negative pore water pressures on a CPT is a red flag for pile design. Negative pore water pressures can be indicative of a pile relaxing and losing capacity! Perform a load test after a couple of weeks to ensure the capacity at EOD is maintained.
