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Experimental Study of the Mechanical Behavior of Plastic Concrete Cutoff Walls

Mousavi, Hamed | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42678 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Jafarzadeh, Fardin
  7. Abstract:
  8. The seepage through foundation of earth dams causes the serious menaces and the reduction in their efficiency. Therefore essential contrivances must be provided against mentioned problem. One of the common and efficient ways to control the seepage through pervious layers under earth dams is plastic concrete cut off wall which is used as a filling material in dam foundation due to the low permeability, plastic behavior and low enough elastic modulus compatible with the adjusted soil. In addition to the mentioned properties, it is important that plastic concrete have an adequate compressive strength to sustain the lateral and vertical loads. Since the change in the ratio W/C (water to cement) and B/C (bentonit to cement) clearly affect the strength of concrete in the opposite directions, consequently the investigation of effects of W/C and B/C on the mechanical strength is necessary to obtain the optimum mix design. In this research, the effects of mix design and confining pressure on compressive strength of plastic concrete is studied. The objective tests were conducted on the specimens made from sixteen different mix designs at unconfined and triaxial state condition. The tests were carried out to study the effect of W/C, B/C , age and confining pressure at ages 7, 28, 240 days. According to the results obtained at the constant B/C, the increase of W/C ratio leads to the decrease in the compressive strength and Elastic Modulus. Also at the constant W/C, the mechanical strength and Elastic Modulus increases due to the increase of B/C. It was seen that the increase in confining pressure not only leads the increase of compressive strength and Elastic Modulus but also causes a change in failure behavior of plastic concrete from brittle to ductile behavior. Also From the test results, It can be seen that the age clearly affects the compressive strength of plastic concrete. Referring to the obtained results at the ages of 7, 28, and 240 days, increase of age leads to an increase in strength and Elastic Modulus in unconfined and triaxial state condition. In Addition, It was observed that the cement content has effect on the rate of increase in compressive strength due to the increase of age. An increasing in the mechanical strength of a mix design with more cement content is more pronounced than the one with less cement content
  9. Keywords:
  10. Plastic Concrete ; Earth Dam ; Cutoff Wall ; Compression Strength ; Elastic Modulus

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