Study on the Mitigative Effect of Controlled Permeable Formwork (CPF) Liner on Early-Age Shrinkage of Box-Girder Concrete

Because of its high binder content and severe construction environment, early-age cracking is one of the most important threats to concrete used in continuous box-girder bridge structures. In this study, controlled permeable formwork (CPF) liner was used to mitigate the early-age shrinkage and reduce the early-age cracking risk of box-girder concrete. Early-age shrinkage was measured by a noncontact method and started at 30 min after adding mix water until 7 d. Internal relative moisture content and pore distribution tests were also carried out to reveal the working mechanism of CPF liner. The results show that covering the concrete surface with CPF liner decreased early-age shrinkage significantly. Under the temperature of 20°C and the relative humidity of 60%, two-surface-covering and three-surface-covering CPF liner on concrete decreased the shrinkage by 44% and 48%, respectively, at 7 d compared with concrete without CPF liner covered on it. The main reason is that CPF liner enhanced the internal relative moisture content and resulted in better performance of the surface concrete.

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Effects of simulated environmental conditions on the internal relative humidity and relative moisture content distribution of exposed concrete

Cement and Concrete Composites ◽

10.1016/j.cemconcomp.2010.09.009 ◽

2011 ◽

Vol 33 (1) ◽

pp. 142-153 ◽

Cited By ~ 29

Author(s):

Dong-Woo Ryu ◽

Jeong-Won Ko ◽

Takafumi Noguchi

Keyword(s):

Relative Humidity ◽

Moisture Content ◽

Environmental Conditions ◽

Content Distribution ◽

Relative Moisture Content ◽

Moisture Content Distribution ◽

Relative Moisture ◽

Internal Relative Humidity

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Myxomycetes on the bark of Banksia attenuata and B. menziesii (Proteaceae)

Australian Journal of Botany ◽

10.1071/bt05079 ◽

2006 ◽

Vol 54 (4) ◽

pp. 357 ◽

Cited By ~ 1

Author(s):

C. C. Jordan ◽

M. H. Brims ◽

E. J. Speijers ◽

E. M. Davison

Keyword(s):

Moisture Content ◽

New Records ◽

Common Species ◽

Species Assemblage ◽

Decomposition Level ◽

Moist Chamber ◽

Relative Moisture Content ◽

Relative Moisture ◽

Banksia Attenuata ◽

Chamber Technique

Myxomycetes on the bark of dead Banksia attenuata and B. menziesii from the Perth metropolitan area of Western Australia were surveyed by the moist chamber technique, to determine whether the flora was similar on both hosts and what were the most important variables that determined the distribution of the most common species. Twenty-seven species of myxomycetes were recovered, including six new records for Australia (Comatricha rigidireta, Echinostelium elachiston, Paradiacheopsis cf. cribrata, P. rigida, Stemonitopsis amoena and S. cf. hyperopta). Members of the order Stemonitales comprised the largest number of species, whereas members of the Liceales occurred on the most bark pieces. The most common species were Licea kleistobolus, Echinostelium minutum, Comatricha elegans, Cribraria minutissima and Paradiacheopsis fimbriata. Overall, B. menziesii and B. attenuata had very similar myxomycete productivity, diversity and species assemblage, as did the tops and bottoms of the logs. It was concluded that they provided very similar microhabitats for myxomycetes. Both pH and the relative moisture content of the bark had an effect on myxomycete productivity. Bark decomposition level, pH and bark surface (top or bottom) were the most important variables determining the distribution of the most common myxomycete species.

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