00676698

Component

http://onlinepubs.trb.org...trr/1994/1458/1458-015.pdf

https://scholar.google.co...HEWS&publication_year=1994

Findings of a 5-year laboratory investigation on the effect of curing on the durability of fly ash concrete are summarized. Three series of concrete mixes were cast such that concretes within a given series were of similar strength grade (nominally 25, 35, or 45 MPa) but varied in fly ash replacement level (0 to 50%). Following casting, concrete specimens were subjected to various curing treatments and subsequently were stored at a range of temperatures and relative humidities before testing. To assess the influence of the various curing and storage regimes on concrete performance, concrete specimens were tested for (a) compressive strength, (b) oxygen permeability, (c) carbonation in both internal and external storage, and (d) resistance to chloride ingress and steel corrosion. Results indicated that, whereas all concretes required adequate curing to achieve their potential properties, concretes containing fly ash were more sensitive to poor curing. The difference was especially marked at higher levels of replacement (50% fly ash), where curtailing the moist-curing period resulted in a large increase in the rate of carbonation and permeability and a marked reduction in compressive strength. Concretes with lower levels of ash (15 to 30%) carbonated at slightly higher rates than the control concretes but generally offered lower permeability. Resistance to the penetration of chloride ions increased as fly ash content increased, irrespective of the level of curing applied to the concrete. Poorly cured, low strength grade (C25) concretes with 50% fly ash provided greater resistance to chloride than higher grade (C45) concretes without ash. Concretes with moderate levels of fly ash (15 to 30%) require no additional curing to provide equal, if not improved, durability compared with opc concrete of the same strength grade. Concretes with higher levels of ash may require extended curing compared with opc concrete, especially if the design of the structure and conditions are conducive to carbonation. Adequately cured, high fly ash content concretes are likely to offer substantially improved durability because of their low permeability and high resistance to chloride ion ingress compared with opc concrete.

This paper appears in Transportation Research Record No. 1458, Concrete Research. 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

01401262

English

p. 99-108

1994

Transportation Research Record

0309060656

Figures (6) ; References (37) ; Tables (3)

Ash content; Carbonation; Chlorides; Compressive strength; Concrete; Concrete curing; Durability; Fly ash; Handling and storage; Laboratory tests; Oxygen; Permeability; Storage facilities

Freight Transportation; Highways; Materials; Terminals and Facilities; I32: Concrete

TRIS, TRB

Apr 28 1995 12:00AM

• ADDITION OF CLASS C FLY ASH TO CONTROL EXPANSIONS DUE TO ALKALI-SILICA REACTION
• DEVELOPMENT OF CONCRETE DURABILITY SPECIFICATION AND RATINGS IN FLORIDA
• EFFECT OF NATURAL POZZOLAN ADDITION ON EXPANSIONS CAUSED BY ALKALI-SILICA REACTION
• EVALUATION AND COMPARISON OF THE PHYSICAL PROPERTIES OF FIBRILLATED POLYPROPYLENE FIBER-REINFORCED CONCRETES
• IMAGE ANALYSIS OF PORTLAND CEMENT CONCRETE AND ASPHALT CONCRETE PAVEMENTS USING SCANNING ELECTRON MICROSCOPE IMAGES (WITH DISCUSSION AND CLOSURE)
• INFLUENCE OF EARLY HEAT CURING ON PROPERTIES OF 100-MPA AIR-ENTRAINED CONCRETE
• INFLUENCE OF LOADING TYPE, SPECIMEN SIZE, AND FIBER CONTENT ON FLEXURAL TOUGHNESS OF FIBER-REINFORCED CONCRETE
• INTERPRETATION OF ACCELERATED TEST METHOD ASTM P214 TEST RESULTS
• MECHANICAL PROPERTIES OF LIGHTWEIGHT CONCRETE INCORPORATING RECYCLED SYNTHETIC WASTES
• NONDESTRUCTIVE IDENTIFICATION OF INTERNALLY DAMAGED AREAS OF CONCRETE BEAM USING THE SPECTRAL ANALYSIS OF SURFACE WAVES METHOD
• OPTIMIZATION OF ROLLER-COMPACTED CONCRETE FOR LOCAL APPLICATION
• PERFORMANCE CHARACTERISTICS OF MONOFILAMENT POLYPROPYLENE FIBER-REINFORCED CONCRETE
• PREDICTION OF CREEP EFFECT IN SEGMENTAL CONCRETE BRIDGE CONSTRUCTION
• RECYCLING CONTAMINATED SPENT BLASTING ABRASIVES IN PORTLAND CEMENT MORTARS
• STABILIZATION AND SOLIDIFICATION OF CONTAMINATED SOILS AND SLUDGES USING CEMENTITIOUS SYSTEMS: SELECTED CASE HISTORIES
• SYSTEM OPTIMIZATION OF FAILURE, CONSTITUTIVE MODELING, AND STRENGTHS OF CONCRETE AND OTHER GEOLOGICAL MATERIALS USING GENETIC ALGORITHM
• USE OF MATURITY AND PULSE VELOCITY TECHNIQUES TO PREDICT STRENGTH GAIN OF RAPID CONCRETE PAVEMENT REPAIRS DURING CURING PERIOD