The improvement in the impermeability of concrete was studied using different methods. The main aim was to investigate impermeability improvement of concrete and to compare these methods. Two different methods were examined to investigate and compare impermeability and strength improvement of concrete by using two different sets of concrete specimens. These methods included the application of coating materials to concrete and the production of concrete using different constituent amounts and types. The first set of concrete specimens was prepared by applying two different coating materials (a coating material including both powder and liquid components / and a coating material including only a liquid component) on reference concrete specimens separately. The second set of concrete specimens was prepared using different proportions of concrete constituents such as cement, water, steel and plastic fibers, mineral and chemical concrete admixtures.
Various tests were conducted on both sets of concrete specimens in order to compare the permeability of concrete specimens. However, some of these tests
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were not applied on all of the specimens because of test and material specifications. The tests were used to evaluate compressive strength, water absorption, chloride ion penetration and depth of water penetration under pressure. These test methods were carried out on concrete cube specimens and concrete cores taken from those specimens according to the relevant standards.
It was found that the permeability of the concrete specimens decreased significantly when the coating material which was composed of the combination of powder and liquid components was applied on concrete specimens. However, permeability did not decrease significantly for concrete specimens coated with the coating material composed of only a liquid component. Significant improvement in the impermeability of the concrete specimens was observed when the amount of cement was increased, the water-to-cement ratio was decreased, mineral admixtures (silica fume and fly ash) and plasticizers were used. This improvement was associated with densification of the concrete microstructure and reduction in capillary pores as a result of pozzolanic reaction and due to reduction in water-to-cement ratio. Coating materials were determined to be effective for concretes with high permeability prior to coating whereas their effect was less significant for lower-initial permeability concretes. Moreover, the effect of coating materials on permeability differed depending on their chemical compositions. The effect of using steel fibers and plastic fibers for the improvement of concrete impermeability was found to be insignificant.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12614214/index.pdf |
| Date | 01 March 2012 |
| Creators | Tekin, Ahmet Veli |
| Contributors | Erdogan, Sinan Turhan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | Access forbidden for 1 year |
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