Based on 770 seawater wet/dry cyclic exposure test,water repellent treatment(WRT) with use of four different types of silane was applied on the surface of cracked concrete to study the influence of WRT on water and Cl~-penetration.Results show that for the concrete not cracked,WRT restrains penetration of water and Cl~-into concrete effectively.If WRT is properly applied on cracked concrete surface even with the crack width of 0.2 mm,special silane treatment can still establish an effective Cl~-barrier.Whil...