Kahsay, Tesfaalem (2014) Study on the Effectiveness of Quality Control for the Production of Reinforced Concrete and Hollow Concrete Blocks (In projects administered by Addis Ababa housing Projects). Masters thesis, Addis Ababa University.
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Abstract
In order to produce reinforced concrete and hollow concrete blocks with good quality which satisfy strength and durability requirements, great care have to be taken for their production starting from ingredient selection to finished product. In addition to this, every production process should follow proper scientific procedures. For this, quality control plays a significant role because qualities of these ingredients and their production process could affect the overall quality of buildings to a higher extent. Quality control comprises a combination of action and decision taken in compliance with specification and checks that these are satisfied. Considering this, investigations focusing on quality control in reinforced concrete and hollow concrete block production has been conducted in projects administered by Addis Ababa Housing Project found in various parts of Addis Ababa located in Yeka Ayat II, Yeka Ayat III, Yeka Abado, Bole Arabsa, Kolfe keranyo, tulu dimtu and kelento sites. The research is carried out by collecting information on qualities of ingredients and method of production through questionnaires and observation and sample compressive strength test result from consultant data file to check their compliance with the help of statistical analysis and minimum strength requirement set on recommended standards. The findings of the investigation have shown that in all construction sites, sufficient tests are not conducted for all ingredients used for production of reinforced concrete and hollow concrete blocks. Among those ingredients, sand testes by some sites for its silt content using jar test, observation and or both. In addition to this, handling of those ingredients were very poor, during observation intermixing coarse and fine aggregate, grass grown on the top of sand, reinforcement bar rests on the ground… were shown and production process also not conducted properly as specified in the recommended standards. According to the result of statistical analysis of concrete compressive strength test collected from consultant data files, the quality control on significant portion of the construction sites are not good. As per the classification of ACI 214, the standard deviation of 46.15 % of the compressive strength has shown that the quality control is not good. From which, none of them fall in the “fair” classification range and 46.15 % in the “poor” range; and the coefficient of variation of 76.92 % of the compressive strength has shown that the quality control is not good from which 15.38 % fall in the “fair” classification range and 61.54 % in the “poor” range. From the analysis of compressive strength test result, 35.14%, 14.86% and 21.62% of the projects has shown defective lots as per the Ethiopian, the American and the British codes compliance requirement respectively. On the other hand, 40% of hollow concrete block producers don’t conduct test and the remaining 60% of them conduct a test for compressive strength, but the result collected from consultant data files, can’t comply class C strength of Ethiopian standard for hollow blocks ES 596:2001. This is an indication that the test results among a significant portion of the investigated projects have shown large variability implying the quality control is unsatisfactory. It is also observed almost one-third of the construction sites have got defective lots, which fail to satisfy the compliance requirement set on the Ethiopian building codes and standards.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Batching, bending, cement, coefficient of variation, compacting, cutting, curing, finishing, mineral aggregates, mixing, placing, quality control, standard deviation, transporting, tying and water. |
| Subjects: | T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General) T Technology > TG Bridge engineering T Technology > TH Building construction |
| Divisions: | Africana |
| Depositing User: | Andriamparany Edilbert RANOARIVONY |
| Date Deposited: | 25 Jul 2018 09:52 |
| Last Modified: | 25 Jul 2018 09:52 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/8072 |
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