TY - JOUR
T1 - Inspection of bridges for effects of air-entrainment on the porosity and compressive strength of concretes
AU - Fulop, Ludovic
AU - Ferreira, Rui Miguel
AU - Bohner, Edgar
AU - Valokoski, Jani
AU - Vuotari, Jussi
AU - Tirkkonen, Timo
N1 - Funding Information:
This work was carried out with funding from the Finnish Transport Infrastructure Agency , under contract Nr. LIVI 3232/02.01.12/2017 011P1 – 0063318 and LIVI 3232/02.01.12/2017 0103I – 0060803 . We thank Liisa Salparanta for her support with the initial planning of this project. The countless bridge inspectors and laboratory technicians are also gratefully acknowledged. Their diligent work provided the basic measurements for the analysis presented here.
Funding Information:
This work was carried out with funding from the Finnish Transport Infrastructure Agency, under contract Nr. LIVI 3232/02.01.12/2017 011P1 – 0063318 and LIVI 3232/02.01.12/2017 0103I – 0060803. We thank Liisa Salparanta for her support with the initial planning of this project. The countless bridge inspectors and laboratory technicians are also gratefully acknowledged. Their diligent work provided the basic measurements for the analysis presented here.
Publisher Copyright:
© 2022 The Authors
PY - 2022/12
Y1 - 2022/12
N2 - Air entrained concrete is used for outdoor structures in cold climate to enhance freeze-thaw resistance. A well dispersed air void system is incorporated in the fresh concrete, consisting of spherical air voids that provide expansion space for freezing water and thus act as pressure-relief. The amount of air entrainment (AE), which results from adding an air entrainment agent to the fresh concrete during mixing, needs to be controlled so as not to significantly reduce the strength of the hardened concrete. Excessive AE has been reported in some bridge concretes in Finland, triggering a comprehensive inspection of 96 bridges. The paper describes the testing methodologies used in this case-study of comprehensive national bridge-inventory level inspection, assess the main findings (compressive strength and porosity), and concludes on the lessons learned concerning the effectiveness of inspection methods. The large dataset of concretes, presented here, was treated statistically. The amount of AE in hardened concrete had been steadily increasing in recent years Salparanta et al. [1]. The study shows the importance of a representative number of samples when conducting inspections and found that the use of rebound hammer and core testing correlation to establish additional in situ strength measurements led to overly conservative results. It was verified that the immediate safety of the inspected bridges was not in question, and that a re-evaluation of the safety margins and special maintenance protocols may be required to assure adequate long-term service life for some of the bridges that exhibited exceptionally high AE.
AB - Air entrained concrete is used for outdoor structures in cold climate to enhance freeze-thaw resistance. A well dispersed air void system is incorporated in the fresh concrete, consisting of spherical air voids that provide expansion space for freezing water and thus act as pressure-relief. The amount of air entrainment (AE), which results from adding an air entrainment agent to the fresh concrete during mixing, needs to be controlled so as not to significantly reduce the strength of the hardened concrete. Excessive AE has been reported in some bridge concretes in Finland, triggering a comprehensive inspection of 96 bridges. The paper describes the testing methodologies used in this case-study of comprehensive national bridge-inventory level inspection, assess the main findings (compressive strength and porosity), and concludes on the lessons learned concerning the effectiveness of inspection methods. The large dataset of concretes, presented here, was treated statistically. The amount of AE in hardened concrete had been steadily increasing in recent years Salparanta et al. [1]. The study shows the importance of a representative number of samples when conducting inspections and found that the use of rebound hammer and core testing correlation to establish additional in situ strength measurements led to overly conservative results. It was verified that the immediate safety of the inspected bridges was not in question, and that a re-evaluation of the safety margins and special maintenance protocols may be required to assure adequate long-term service life for some of the bridges that exhibited exceptionally high AE.
KW - Air-entrained concrete
KW - Bridges
KW - In-situ compressive strength
KW - Inspection methods
UR - http://www.scopus.com/inward/record.url?scp=85131969621&partnerID=8YFLogxK
U2 - 10.1016/j.cscm.2022.e01211
DO - 10.1016/j.cscm.2022.e01211
M3 - Article
SN - 2214-5095
VL - 17
JO - Case Studies in Construction Materials
JF - Case Studies in Construction Materials
M1 - e01211
ER -