J.M. NICHOLS ⁽¹⁾, A. MASHADI ⁽²⁾, L.H. FEIGENBAUM ⁽³⁾ and K.T. GLOWACKI ⁽⁴⁾

 ⁽¹⁾ Associate Professor, Department of Construction Management, Texas A&M University,

College Station, Texas – 77840, USA. Email: jm-nichols@tamu.edu

⁽²⁾ Graduate Student, Department of Construction Management, Texas A&M University,

College Station, Texas – 77840, USA

⁽³⁾ Assistant Dean, College of Architecture, Texas A&M University,

College Station, Texas – 77840, USA. Email: leslief@tamu.edu

⁽⁴⁾ Associate Professor, Department of Architecture, Texas A&M University, College Station, Texas – 77840, USA

ABSTRACT

The bond wrench test was developed in Australia as an efficient replacement for the masonry beam test. The masonry beam test provided only one flexural bending result for each beam, where the bond wrench provides (n-1) test results for n high stack bonded prisms. A number of studies of four different types of bond wrenches have been completed at Texas A&M University in the last decade. These wrenches include the Australian Standard (AS) Bond Wrench, ASTM C-1072 Bond Wrench and two new wrenches termed the TAMU Balanced Bond Wrench and the TAMU Unbalanced Bond Wrench. The purpose of this paper is to report on the bias observed between the Australian Standard Bond Wrench and the ASTM E518 Beam Test during recent testing using stack bonded prisms. Fifty prisms were constructed using six bricks for each prism. The prisms were constructed using two masons, who used a mortar comprising 1 part cement to 1 part hydrated lime to 6 parts clean sand. A brick manufactured in Texas was used for the experimental work. The prisms were randomly assigned to each of two test sets to avoid manufacturing bias. Twenty five prisms were tested using the ASTM beam test and 25 tested using the AS bond wrench. The results show a consistent bias between the test procedures with the AS Bond Wrench providing higher bond strength measurements than the beam test. The bias was statistically significant at the 5% level.

KEYWORDS: bond strength; flexural stress; masonry; bond wrench; beam test.