Mashadi, Aga Adnan Ali (2016-04). Bond Strength Measurements from an Australian Standard Bond Wrench and ASTM E518 Bond Wrench. Master's Thesis.
Thesis
Flexural bond strength is a significant factor that governs the mortar to brick bond performance under different loading conditions for masonry walls and columns. Bond testing is a fairly recent addition to the masonry designer's tool box, with the dominant test over the last 150 years being the compression test. Several methods have been developed to test the masonry bond, with the bond wrench from Australia being one of the simpler tests to perform on a masonry stack. The original bond wrench evolved from the beam tests, as outlined in ASTM E518, with the aim of improving the statistical information measured from the manufactured masonry prisms. There have been different bond wrenches developed in Australia and the USA. Four bond wrenches have been studied in the last decade at TAMU, termed the ASTM Wrench, the Australian Wrench, the TAMU Balanced Wrench and the TAMU Unbalanced Wrench. An extensive set of results shows a difference exists in the bias and precision results for standard masonry prisms tested with different wrenches. This study's aim is to compare the Australian Bond Wrench results to the ASTM E518 Beam Test results to gain an understanding of the statistical properties for the results from the different tests. The tests used a standard Western King sized clay brick manufactured in Texas. A total of fifty masonry prisms were built and tested in the same weather conditions. Each prism consisted of six bricks with five joints, and the mortar used was 1:1:6 with Portland cement to lime to sand. Each test group had 25 replicates. The results show that the mean flexural strength values of Australian Bond Wrench were determined to be statistically higher than ASTM E518 beam mean flexural strength values. A reasonable conclusion is that results obtained using ASTM E518 were low because the results reflect the failure in a weaker joint in the prism and not average results for all joints. The Australian Bond Wrench measures the capacity of each joint in the prism. Further research can be conducted with the use of Texan red brick. Other bond wrenches can be compared with these methods to analyze the presence of bias between the different results.
