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| dc.contributor.author | Yenehun, Biruk | |
| dc.date.accessioned | 2020-03-16T05:44:49Z | |
| dc.date.available | 2020-03-16T05:44:49Z | |
| dc.date.issued | 2020-03-15 | |
| dc.identifier.uri | http://hdl.handle.net/123456789/10271 | |
| dc.description.abstract | It is everyone’s interest to use locally available sand for concrete production. However, the sand sources around Bahir Dar contain a high amount of silt than limited by codes as not to exceed 5%. The silt causes a reduction in workability and compressive strength of concrete. So, to use locally available sand, it is necessary to compensate the negative effects of high silt present in the sand on concrete workability and compressive strength. This study attempted to evaluate compensation measures and to determine the appropriate amount of water, additional cement and dosage of high range water-reducer (HRWR) admixture in compensating the 7%, 10% and 15% silt content. It also attempted to compare the cost of compensation methods which are the cost of washing sand until its’ silt content is reduced to 5%, additional cement needed to compensate for the effect of high silt and HRWR admixture for slump reduction. Two sand samples with 10% and 15% silt content were prepared and washed to reduce the silt content to 5% to determine the cost of washing sand. Totally, 5 series of concrete mixes were prepared with 0%, 5%, 7%, 10% and 15% silt content to be tested for slump and compressive strength test. In 7%, 10%, and 15% silt content concrete mix series, specimens were prepared with increasing the cement content and using HRWR admixture. For the concrete mix that contains 7% and 10% silt, use of the HRWR admixture were found to give higher compressive strength above other compensation methods gained and even the control mix. For concrete mixes that contain 15% silt, only the concrete mix with 50% additional cement gains the same compressive strength as the control mix achieved. When cost-effectiveness evaluation was done among the compensation methods, washing the sand found to be cost-effective. Washing the sand increases the concrete material cost to produce 1 m3 of concrete by 13% and 18% for 10% and 15% silt content, respectively. Use of HRWR admixture for 7% and 10% silt causes 18% and 22% concrete material cost increase, respectively. Additional cement causes a 34% concrete material cost increase for 15% silt content. Keywords | en_US |
| dc.language.iso | en | en_US |
| dc.subject | Construction Technology and Management | en_US |
| dc.title | Evaluation of Cost-Effective Methods for Compensating the Negative Effects of High Silt Present in Natural Sand on Compressive Strength and Workability of Concrete | en_US |
| dc.type | Thesis | en_US |
