Influence of reinforcement spacers on mass transport properties and durability of concrete structures
File(s)
Accepted version
Author(s)
Alzyoud, S
Wong, HS
Buenfeld, NR
Type
Journal Article
Abstract
Spacers are ubiquitous in reinforced concrete, but their influence on durability is unclear. This paper presents the first study on the effects of spacers on mass transport and microstructure of concrete. Samples with different spacers, cover depths, aggregate sizes, curing ages and conditioning were subjected to diffusion, permeation, absorption and chloride penetration, and to μXRF, BSE microscopy and image analysis. Results show that spacers increase transport in all cases, the magnitude depending on spacer type and transport mechanism. Plastic spacers produced the largest increase, followed by cementitious spacers and then steel chairs. The negative effect is due to a porous spacer-concrete interface that spans the cover where preferential transport occurs. Spacers may seem low value, small and inconsequential, but because they are placed every ≤ 1 m along rebars, their overall effect on ingress of external media is significant. This is not currently recognised by standards or by most practitioners.
Date Issued
2016-09-01
Date Acceptance
2016-05-19
Citation
Cement and Concrete Research, 2016, 87 (10), pp.31-44
ISSN
1873-3948
Publisher
Elsevier
Start Page
31
End Page
44
Journal / Book Title
Cement and Concrete Research
Volume
87
Issue
10
Copyright Statement
© 2016 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Subjects
Science & Technology
Technology
Construction & Building Technology
Materials Science, Multidisciplinary
Materials Science
Durability
Interfacial transition zone
Microstructure
Transport properties
Spacers
INTERFACIAL TRANSITION ZONE
CEMENT-BASED MATERIALS
DIFFUSIVITY
MICROSTRUCTURE
MICROCRACKING
AGGREGATE
Building & Construction
0904 Chemical Engineering
0905 Civil Engineering
1202 Building
Publication Status
Published
Date Publish Online
2016-06-01