Imperial College London
Portrait Picture

Professor Nick Buenfeld

Faculty of Engineering, Department of Civil and Environmental Engineering

Professor of Concrete Structures
 
 
 
//

Contact

 

n.buenfeld Website

 
 
//

Location

 

228BSkempton BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Wong:2020:10.1617/s11527-020-1458-2,
author = {Wong, H and Poole, AB and Wells, B and Eden, M and Barnes, R and Ferrari, J and Fox, R and Yio, MHN and Copuroglu, O and Guðmundsson, G and Hardie, R and Jakobsen, UH and Makoubi, K and Mitchinson, A and Raybould, P and Strongman, J and Buenfeld, N},
doi = {10.1617/s11527-020-1458-2},
journal = {Materials and Structures},
title = {Microscopy techniques for determining water-cement (w/c) ratio in hardened concrete: A round-robin assessment},
url = {http://dx.doi.org/10.1617/s11527-020-1458-2},
volume = {53},
year = {2020}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Water to cement (w/c) ratio is usually the most important parameter specified in concrete design and is sometimes the subject of dispute when a shortfall in concrete strength or durability is an issue. However, determination of w/c ratio in hardened concrete by testing is very difficult once the concrete has set. This paper presents the results from an inter-laboratory round-robin study organised by the Applied Petrography Group to evaluate and compare microscopy methods for measuring w/c ratio in hardened concrete. Five concrete prisms with w/c ratios ranging from 0.35 to 0.55, but otherwise identical in mix design were prepared independently and distributed to 11 participating petrographic laboratories across Europe. Participants used a range of methods routine to their laboratory and these are broadly divided into visual assessment, measurement of fluorescent intensity and quantitative backscattered electron microscopy. Some participants determined w/c ratio using more than one method or operator. Consequently, 100 individual w/c ratio determinations were collected, representing the largest study of its type ever undertaken. The majority (81%) of the results are accurate to within ± 0.1 of the target mix w/c ratios, 58% come to within ± 0.05 and 37% are within ± 0.025. The study shows that microscopy-based methods are more accurate and reliable compared to the BS 1881-124 physicochemical method for determining w/c ratio. The practical significance, potential sources of errors and limitations are discussed with the view to inform future applications.
AU  - Wong,H
AU  - Poole,AB
AU  - Wells,B
AU  - Eden,M
AU  - Barnes,R
AU  - Ferrari,J
AU  - Fox,R
AU  - Yio,MHN
AU  - Copuroglu,O
AU  - Guðmundsson,G
AU  - Hardie,R
AU  - Jakobsen,UH
AU  - Makoubi,K
AU  - Mitchinson,A
AU  - Raybould,P
AU  - Strongman,J
AU  - Buenfeld,N
DO  - 10.1617/s11527-020-1458-2
PY  - 2020///
SN  - 1359-5997
TI  - Microscopy techniques for determining water-cement (w/c) ratio in hardened concrete: A round-robin assessment
T2  - Materials and Structures
UR  - http://dx.doi.org/10.1617/s11527-020-1458-2
UR  - https://link.springer.com/article/10.1617%2Fs11527-020-1458-2
UR  - http://hdl.handle.net/10044/1/77685
VL  - 53
ER  -
Download