Durability of High Early Strength Silica Fume Concretes Subjected to Accelerated and Normal Curing
Colin D. Johnston
Appears on pages(s):
accelerated curing; bridge girders; chlorides; curing; deicers; durability; freeze-thaw durability; high-strength concretes; permeability; precast concretes; scaling; silica fume; Materials Research
The short-term strength development and long-term durability of silica fume concretes is investigated for mixtures intended to be alternatives to those without silica fume currently used in precast prestressed concrete bridge girder production in Alberta, Canada, where accelerated curing at 65 C to obtain specified strengths of 28 MPa at 16 hr and 35 to 42 MPa at 28 days is normal industry practice. Concretes with 300 kg/m 3 and 450 kg/m 3 of normal cement, each with 10 percent silica fume by weight of cement, were examined for strength development, entrainment at air-void parameters, resistance to rapid freezing and thawing in water, resistance to deicer scaling in 3 percent NaCl solution, and chloride permeability by the applied-voltage technique. Silica fume was found to significantly enhance all aspects of durability relevant to exposure conditions involving freezing and thawing with deicers. Varying degrees of short- and long-term strength improvement and reduced cost in cementitious materials are also possible as a consequence of using silica fume.