curing agent for concrete MRK-20(Sodium) curing agent for concrete MRK-21(Potassium) PictureDescriptionFeature and function ... important.Hardness:MRK-20,21 can increase 19%-180%Anti-impact ability:Increase above 18%Wear corrosion resistance: ... dock, port, hypermarket, warehouse and distribution center, school, cool house, gym, hospital, community, Brand monopolization, factory, urban construction, ...