Choudhary, Rishav (2015-04). Bond Strength Measurements from a TAMU Balanced Bond Wrench in Comparison to Brick Prism ASTM E518 Beam Test. Master's Thesis.
Thesis
The brick to mortar bond strength affects the performance of the joints in brick masonry when subjected to various loading conditions. The flexural bond strength of masonry units can be measured using a bond wrench or a standard test like ASTM E518 beam test. The early bond wrenches were developed in the 1980s in Australian laboratories. In 2011, an Australian bond wrench was manufactured and consequently an ASTM C1072 Bond Wrench was developed in 2012. Further research was done in the field and two more lightweight bond wrenches, i.e. balanced and unbalanced, were built by Indian students at Texas A&M University. Several researchers have performed experiments to study the bias between different bond wrenches. These researches illustrated that no unacceptable bias existed in the flexural strength values calculated using the Indian balanced and unbalanced wrench. However, there existed a bias between American Bond Wrench and Australian Bond wrenches according to research. This thesis aims at understanding the bias between balanced bond wrench developed at Texas A&M University and Standard ASTM E518 beam test method. Also, Indian balanced and unbalanced bond wrench would be referred as TAMU (Texas A&M University) balanced and unbalanced bond wrench in this report. A total of 50 prisms using Portland cement and Texan bricks were built for this experimental research. The prisms were built in two sets and each prism comprised of six bricks with five joints. The mortar used here was 1:1:6 (cement: lime: sand). The samples were cured for a period of 07 days, and all the experiments were carried out under same weather conditions. TAMU balanced bond wrench was used to test the first set of prisms and second set of prisms were tested using standard ASTM E518 beam method. A Student's t-Test analysis was run between the flexural strength values of the TAMU balanced wrench and ASTM E518 method. From the plots, it can be inferred that the mean value of the American standard was low when compared with the mean values of the balanced bond wrench. The plots of ASTM E518 method and TAMU balanced were quite dissimilar. Further research is recommended using the Texas red brick.
