Q. Application of bitumen to driven piles?

In a certain area of H-piles subjected to ground water table fluctuation, painting is occasionally applied on the surface of H-piles because the rise and fall of water table contribute to the corrosion of H-piles. Conversely to decrease the effect of extra loads brought about by negative skin friction, bitumen is applied on the pile surface corresponding to the region of soils which has negative skin friction. Though bitumen must not be applied to the whole section of H-piles since it will be unable to derive the designed frictional reaction from soils. Essentially some engineers have reservation of the effectiveness of bitumen slipcoat since bitumen can get removed during pile driving.