Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Plastic Shrinkage Cracking in Concrete
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Early-age (up to 24 hours after casting) cracking may become problematic in any concrete structure. It can damage the aesthetics of the concrete member and decrease the durability and serviceability by facilitating the ingress of harmful material. Moreover, these cracks may expand gradually during the member’s service-life due to long-term shrinkage and/or loading. Early-age cracking is caused by two driving forces: 1) plastic shrinkage cracking which is a physical phenomenon and occurs due to rapid and excessive loss of moisture, mainly in form of evaporation, 2) chemical reactions between cement and water which causes autogenous shrinkage. In this PhD project only the former is investigated.

Rapid evaporation from the surface of fresh concrete causes negative pressure in the pore system. This pressure, known as capillary pressure, pulls the solid particles together and decreases the inter-particle distances, causing the whole concrete element to shrink. If this shrinkage is hindered in any way, cracking may commence. The phenomenon occurs shortly after casting the concrete, while it is still in the plastic stage (up to around 8 hours after placement), and is mainly observed in concrete elements with high surface to volume ratio such as slabs and pavements.

Many parameters may affect the probability of plastic shrinkage cracking. Among others, effect of water/cement ratio, fines, admixtures, geometry of the element, ambient conditions (i.e. temperature, relative humidity, wind velocity and solar radiation), etc. has been investigated in previous studies. In this PhD project at Luleå University of Technology (LTU), in addition to studying the influence of various parameters, effort is made to reach a better and more comprehensive understanding about the cracking governing mechanism. Evaporation, capillary pressure development and hydration rate are particularly investigated in order to define their relationship.

This project started with intensive literature study which is summarized in Papers I and II. Then, the main objective was set upon which series of experiments were defined. The utilized methods, material, investigated parameters and results are presented in Papers III and IV.

It has been so far observed that evaporation is not the only driving force behind the plastic shrinkage cracking. Instead a correlation between evaporation, rate of capillary pressure development and the duration of dormant period governs the phenomenon. According to the results, if rapid evaporation is accompanied by faster capillary pressure development in the pore system and slower hydration, risk of plastic shrinkage cracking increases significantly.

Place, publisher, year, edition, pages
Luleå, 2016.
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-133ISBN: 978-91-7583-678-2 (print)ISBN: 978-91-7583-679-9 (electronic)OAI: oai:DiVA.org:ltu-133DiVA: diva2:971011
Presentation
2016-10-27, F1031, Luleå, 14:00
Available from: 2016-09-15 Created: 2016-09-15 Last updated: 2016-10-25Bibliographically approved

Open Access in DiVA

fulltext(8932 kB)825 downloads
File information
File name FULLTEXT01.pdfFile size 8932 kBChecksum SHA-512
02c8fea1e36ed216c130cdc58ef14e1243a49af7805ac6ac495af8208a2bfce4e3ced78bdf314e77a82068aebe605155abc2f0e7c80bea39de3421d3edec6866
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Sayahi, Faez
By organisation
Department of Civil, Environmental and Natural Resources Engineering
Infrastructure Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 825 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 634 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf