Integral waterproofing uses chemical admixtures, usually a dry powder or liquid added to the concrete mix at the batch plant or the jobsite. Some forms of integral waterproofing will even self-heal minor cracking. The chemical composition of each products are slightly different, they all are either densifiers, repellants or crystalline admixtures.  Densifiers fill the microscopic pores in the concrete matrix to eliminate water infiltration.  Water repellants make the concrete hydrophobic.  Crystalline admixtures cause microscopic, water-blocking crystals to seal pores and hairline fractures.