Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Controlling capillary pressure in concrete to prevent plastic shrinkage cracking
Dissertation (MEng(Structural Engineering))--University of Pretoria,2022
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
University of Pretoria
2023
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613472687128576 |
|---|---|
| access_status_str | Open Access |
| author2 | Boshoff, William P |
| author_browse | Boshoff, William P |
| author_facet | Boshoff, William P |
| collection | Thesis |
| dc_rights_str_mv | © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng(Structural Engineering))--University of Pretoria,2022 |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/89803 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:36:41.872Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/89803 Controlling capillary pressure in concrete to prevent plastic shrinkage cracking Boshoff, William P stiaandeysel@gmail.com Smit, Martha S Deysel, Renier Christiaan Plastic Shrinkage Plastic Shrinkage Cracking Fresh Concrete Capillary Pressure Tensiometers Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-11 SDG-11: Sustainable cities and communities Engineering, built environment and information technology theses SDG-12 SDG-12: Responsible consumption and production Engineering, built environment and information technology theses SDG-13 SDG-13: Climate action Dissertation (MEng(Structural Engineering))--University of Pretoria,2022 Plastic shrinkage cracking occurs in concrete members with large exposed surface areas, such as concrete pavements, bridge decks and floor slabs. Current research has shown that a notable increase in plastic shrinkage was observed in the engineering practice, leading to considerably more cracking problems than in the past. Plastic shrinkage cracking occurs when the plastic shrinkage of fresh concrete is restrained, leading to tensile stresses, which result in cracks when the tensile strength is exceeded. Plastic shrinkage is caused by negative capillary pressure build-up in fresh concrete. Controlling the negative capillary pressure build-up makes it possible to reduce the risk of plastic shrinkage cracking. The aim of this study was to develop a model that uses live in-situ capillary pressure measurements in fresh concrete to control the capillary pressure build-up to prevent plastic shrinkage cracking at any evaporation rate. A model was developed that calculates a critical pressure limit for when an action is needed to prevent plastic shrinkage cracking. The model uses the negative capillary pressure build-up area between two crucial time points in plastic shrinkage to determine this limit. The proposed model was tested and verified in two phases. The testing and verification of the model were conducted on a low bleed concrete having a water/cement ratio of 0.5 and a self-compacting concrete with a water/cement ratio of 0.4. Tensiometers were used to measure the capillary pressure build-up in concrete. The first phase consisted of determining the parameters required for the model. The second phase used the determined parameters to test the model with the two concrete mixtures at various evaporation rates. The results showed that the model could determine a critical pressure limit relevant to the concrete and evaporation rate. The proposed model proved to be a valuable tool in controlling the capillary pressure and preventing plastic shrinkage cracking in low bleed and self-compacting concrete. mi2025 Civil Engineering MEng(Structural Engineering) Unrestricted SDG-09: Industry, innovation and infrastructure SDG-11: Sustainable cities and communities SDG-12: Responsible consumption and production SDG-13: Climate action 2023-02-24T07:03:08Z 2023-02-24T07:03:08Z 2023 2022 Dissertation *Deysel, RC 2022, Controlling capillary pressure in concrete to prevent plastic shrinkage cracking, MEng Dissertation, University of Pretoria, Pretoria https://repository.up.ac.za/handle/2263/89803 https://doi.org/10.25403/UPresearchdata.22083506 en © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Plastic Shrinkage Plastic Shrinkage Cracking Fresh Concrete Capillary Pressure Tensiometers Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-11 SDG-11: Sustainable cities and communities Engineering, built environment and information technology theses SDG-12 SDG-12: Responsible consumption and production Engineering, built environment and information technology theses SDG-13 SDG-13: Climate action Controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| title | Controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| title_full | Controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| title_fullStr | Controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| title_full_unstemmed | Controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| title_short | Controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| title_sort | controlling capillary pressure in concrete to prevent plastic shrinkage cracking |
| topic | Plastic Shrinkage Plastic Shrinkage Cracking Fresh Concrete Capillary Pressure Tensiometers Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-11 SDG-11: Sustainable cities and communities Engineering, built environment and information technology theses SDG-12 SDG-12: Responsible consumption and production Engineering, built environment and information technology theses SDG-13 SDG-13: Climate action |
| url | https://repository.up.ac.za/handle/2263/89803 https://doi.org/10.25403/UPresearchdata.22083506 |