00605612

Component

http://onlinepubs.trb.org...trr/1990/1284/1284-005.pdf

https://scholar.google.co...rage&publication_year=1990

Results of tests carried out to investigate the causes of early-age cracking reported in some precast, prestressed, steam-cured structural members are reported. Cracks have been observed at the fabrication site even before structures are put into use. An investigation was conducted into the development of concrete physical properties at early ages when the concrete is steam cured. Properties investigated were compressive strength, elastic modulus, splitting tensile strength, and Poisson's ratio. A prestressed concrete producer sample was used in the fabrication of conventional 6- x 12-in. cylinder test specimens. Test results were obtained for 8 hr, 14 hr, 1 day, 2 days, 3 days, 7 days, and 28 days. Tests were carried out on both steam-cured and companion standard moist-cured specimens for comparison. Steam curing was found to be beneficial to the development of all the physical properties only at early ages. The beneficial effect was found to be the least lasting on the tensile strength development in which the benefit appeared to have ceased even before steam curing was discontinued. This resulted in lower tensile strength value for the steam-cured specimens when compared with the values for their standard moist-cured companions. The observed low tensile strength developed in steam-cured specimens may be responsible, at least partially, for the cracking reported during strand release and form stripping at prestressing plants.

This paper appears in Transportation Research Record No. 1284, Cement, Admixtures, and Concrete 1990. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01411065

p. 31-36

1990

Transportation Research Record

0309050634

Figures (10) ; References (16) ; Tables (3)

Alternatives analysis; Compressive strength; Concrete; Concrete curing; Cracking; Curing agents; Development; Modulus of elasticity; Physical properties; Poisson ratio; Precast concrete; Prestressed concrete; Specimens; Steam curing; Tensile strength; Time

Concrete cracking; Moist curing

Highways; Materials; I32: Concrete

TRIS, TRB, ATRI

Mar 31 1991 12:00AM

• ASSESSING IN SITU STIFFNESS OF CURING PORTLAND CEMENT CONCRETE WITH SEISMIC TESTS
• COMPARISON OF MECHANICAL PROPERTIES OF HIGH-STRENGTH CONCRETE MADE WITH DIFFERENT RAW MATERIALS
• EARLY-AGE CEMENT HYDRATION REACTIONS
• HIGH-PERFORMANCE SILICA FUME (MICROSILICA)--MODIFIED CEMENTITIOUS REPAIR MATERIALS
• LONG-TERM OUTDOOR EXPOSURE EVALUATION OF CONCRETE SLABS CONTAINING EPOXY-COATED REINFORCING STEEL
• OPTIMIZATION OF CONCRETE MIXES FOR COST-EFFECTIVE CONSTRUCTION
• OVERVIEW OF THE USE OF FLY ASH CONCRETE IN HIGHWAY CONSTRUCTION
• PENETRATING SEALERS FOR CONCRETE: SURVEY OF HIGHWAY AGENCIES
• PREDICTION OF CONCRETE PROPERTIES USING COARSE AGGREGATE CHEMICAL COMPOSITION DATA
• RATES OF DEVELOPMENT OF PHYSICAL PROPERTIES OF CONCRETE AT EARLY AGES
• SHEAR INTERACTION OF HIGH-STRENGTH TWO-LAYERED CONCRETES AT EARLY AGES PLACED IN SUBFREEZING TEMPERATURES
• USING STATISTICAL METHODS TO OPTIMIZE HIGH-STRENGTH CONCRETE PERFORMANCE