Bond Strength Measurements from an Australian Standard Bond Wrench in Comparison to the Unbalanced ASTM C 1072 Bond Wrench to the Balanced and Unbalanced Wrenches



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Bond strength is one of the most important factors that affect the performance of the joint under various loading conditions. The flexural bond strength of a joint can be measured using a bond wrench. The first of the bond wrenches was developed in 1980s in the Australian laboratories. Former TAMU students had built a lightweight Indian unbalanced and balanced bond wrench. An Australian bond wrench was manufactured in 2011 and subsequently in 2012 an ASTM C 1072 Bond Wrench was developed.

Previous researchers have found out that no unacceptable bias existed in the flexural strength values forecasted using the Indian balanced and unbalanced wrench.The studies have also shown that there exists a bias between American Bond Wrench and Australian Bond wrenches. The Australian wrench values were significantly higher than the American bond wrenches for similar types of samples. Hence it was recommended that the tests be carried out by replacing the cement with Portland cement.

This experimental research uses Portland cement and a total of 50 prisms was built in two sets. Each prism comprised of six bricks with five joints, and all the bricks used were Texan bricks. The mortar used here was 1:1:6. The samples were cured for a period of 28 days, and all the experiments swere carried out under same weather conditions The first set prisms was tested using Australian and the American bond wrench., the second set of prims was tested using the other two wrenches.

A Student?s t-Test analysis was run between the flexural strength values of the four wrenches. From the plots, it can be inferred that the mean value of the American wrench was low when compared with the mean values of the other three wrenches. The plots of Australian bond wrench and Indian unbalanced were quite similar.

It can be concluded that the values forecasted using the American bond wrench were statistically different from the other three wrenches, and the reason can be noted as the difficulty in using the American bond wrench.

Further research is recommended using the Texas red brick.