introduCtion Definitions of Chloride Exposure Classes7 ConCrete pipe C-1: Structurally reinforced concrete exposed to chlorides with or without freezing and thawing conditions. Examples: bridge decks, parking decks and ramps, portions of marine structures located in tidal and splash zone. C-2: Non structurally reinforced (plain) concrete exposed to chlorides and freezing and thawing. Examples: garage floors, porches, steps, pavements, sidewalks, curbs and gutters. C-3: Continuously submerged concrete exposed to chlorides but not freezing and thawing. Examples: underwater portions of marine structures. C-4: Non-structurally reinforced concrete exposed to chlorides but not freezing and thawing. Examples: underground parking slabs on grade stormwater treatment teChnologies As with sulfate exposure, standard Lafarge concrete mixes exceed the exposure class recommendations for chloride. In general, Lafarge concrete pipe should not require any additional protective measures where chloride concentrations are less than 20,000 ppm. Class of Exposure C-1 C-2 C-3 C-4 Maximum Water to Cementing Materials Ration 0.40 0.45 0.50 0.55 Minimum Specified 28-day Compressive Strength (MPa) 35 32 30 25 box seCtions manhole and CatCh basin material 7 Design and Control of Concrete Mixtures, 7th Edition, Cement Association of Canada, 2002, pages 132 and 133. LAFARGE PIPE eMANUAL PAGE 53