Development of High Early Strength Concrete for Prestressed Concrete Applications

摘要

This report describes the development of high early strength concrete withlocally available materials in North Carolina and normal production and curing procedures used in precast/prestressed concrete plant. After many trial batches, two different mixture proportions were developed in the laboratory and three additional mixture proportions were developed for field production. The mixtures contained approximately 850 lbs/cy (504 kg/cu m) of Type III cement, 1027 lbs/cy (609 kg/m) of fine aggregate, and 1764 lbs/cy (1047 kg/m3) of course aggregate with a W/C of 0.34. Melamine-based HRWR was used to enhance the workability with a slump ranging from 3.5 in (89 mm) to 7.5 in. (191 mm). Air entraining agent was also used to achieve an air content of 3% to 4.5%. The concretes developed a compressive strength of 7,000 psi (48 MPa) in 18 hours and 10,000 psi (69 MPa) in 28 days.