Title: Effect of Curing Method and Final Moisture Condition on Compressive Strength of Concrete

Author(s): Sandor Popovics

Publication: Journal Proceedings

Volume: 83

Issue: 4

Appears on pages(s): 650-657

Keywords: air; compressive strength; concretes; curing; drying; epoxy resins;moist curing: moisture; moisture content; wetting.

DOI: 10.14359/10658

Date: 7/1/1986

Abstract:
Specimens were prepared from a concrete batch and kept in molds for the first 24 hours, then divided into groups. Each group was cured at standard 73 F (23 C) temperatures but under different wetness conditions before compressive strength was tested. The procedure was repeated with two more batches of different compositions. Curing methods differed with varying combinations of fog room and air curing. Results show not so much that a concrete is stronger in an air-dry state than in a wet state, as has been previously recognized, but rather that a concrete specimen provides higher compressive strength in a drying state than in a rewetting state. A drying state is when the surface of the concrete is dryer than the inside. A possible mechanism is offered for these strength differences. Practical significance of the experiment includes a contribution to a better interpretation of the results of compressive strength tests and an indication that fluctuations in strength results can be reduced by tightening curing specifications. The results may also lead to a better understanding of the source of strength in a hardened cement paste.