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Keywords: bond strength, polymer-modified lightweight concrete, pull-out test, SBR-latex.

Summary

Many natural aggregates for concrete materials are being been exhausted, hence it is important to utilize by-products from industrial waste as compounds for concrete mixes. However, artificial lightweight concrete has a lower elasticity and strength. To improve these disadvantages, there have been some attempts to use polymers in order to enhance concrete strength. In this paper, we focus on the bond strength of deformed bars embedded in the polymer-modified lightweight aggregate concrete, which is manufactured by using bottom ashes. A pull-out test was performed on the lightweight and polymer-modified lightweight concrete specimens and the test parameters include the compressive concrete strength, diameters of reinforcing bars and their embedment lengths. Normal concrete specimens with a similar compressive strength to that of the polymer-modified lightweight aggregate concrete specimens were also tested for comparison purpose. The bond stress-slip responses and modes of failure were identified during the test. In both of the normal and polymer-modified lightweight concrete specimens, the pull-out failure tends to occur more frequently as the embedment length or the diameter of a rebar becomes smaller. However, more concrete spalling failures occurred in the polymer-modified lightweight concrete specimens than in the normal concrete specimens. This seems to arise because the lightweight concrete has a lower tensile strength than normal concrete. The bond strength is decreased as the embedment length of a steel bar is increased. This is thought to be the results of the nonlinear distribution of bond stress at the concrete-bar interface. The diameter of a reinforcing bar does not make any significant effect on the average bond stress. Both of ACI-408 and Orangun's equations are conservative if the embedment length is relatively small. However, they may provide inaccurate estimates for a bar with a long embedding length.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 96 PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping and Y. Tsompanakis Paper 37 Bond Strength of Deformed Bars in Polymer-Modified Lightweight Aggregate Concrete M.S. Kim, Y.H. Lee, D.J. Kim and H. Kim Department of Architectural Engineering, Kyung Hee University, Yongin, Republic of Korea doi:10.4203/ccp.96.37 purchase the full-text of this paper Full Bibliographic Reference for this paper M.S. Kim, Y.H. Lee, D.J. Kim, H. Kim, "Bond Strength of Deformed Bars in Polymer-Modified Lightweight Aggregate Concrete", in B.H.V. Topping, Y. Tsompanakis, (Editors), "Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 37, 2011. doi:10.4203/ccp.96.37 Keywords: bond strength, polymer-modified lightweight concrete, pull-out test, SBR-latex. Summary Many natural aggregates for concrete materials are being been exhausted, hence it is important to utilize by-products from industrial waste as compounds for concrete mixes. However, artificial lightweight concrete has a lower elasticity and strength. To improve these disadvantages, there have been some attempts to use polymers in order to enhance concrete strength. In this paper, we focus on the bond strength of deformed bars embedded in the polymer-modified lightweight aggregate concrete, which is manufactured by using bottom ashes. A pull-out test was performed on the lightweight and polymer-modified lightweight concrete specimens and the test parameters include the compressive concrete strength, diameters of reinforcing bars and their embedment lengths. Normal concrete specimens with a similar compressive strength to that of the polymer-modified lightweight aggregate concrete specimens were also tested for comparison purpose. The bond stress-slip responses and modes of failure were identified during the test. In both of the normal and polymer-modified lightweight concrete specimens, the pull-out failure tends to occur more frequently as the embedment length or the diameter of a rebar becomes smaller. However, more concrete spalling failures occurred in the polymer-modified lightweight concrete specimens than in the normal concrete specimens. This seems to arise because the lightweight concrete has a lower tensile strength than normal concrete. The bond strength is decreased as the embedment length of a steel bar is increased. This is thought to be the results of the nonlinear distribution of bond stress at the concrete-bar interface. The diameter of a reinforcing bar does not make any significant effect on the average bond stress. Both of ACI-408 and Orangun's equations are conservative if the embedment length is relatively small. However, they may provide inaccurate estimates for a bar with a long embedding length. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £130 +P&P)
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