Strength characteristics of hydraulic lime mortared brickwork

This paper presents experimental results from an ongoing study investigating the flexural bond strength, initial shear strength and compressive strength of brickwork built using natural hydraulic lime mortars. All tests were conducted in accordance with relevant standard procedures. Flexural bond strengths, with planes of failure parallel and perpendicular to bed joints, were determined by panel (wallette) tests. Bond wrench testing of stack-bonded prisms was also conducted to investigate further the material influences on flexural strength. The main parameters studied in this investigation were mortar mix design (binder : aggregate ratio; lime grade) and brick water absorption characteristics. The flexural bond strength and initial shear strength of the brickwork in general increased with mortar strength, but flexural bond strength was significantly impaired by both low and high brick water absorption. The bond wrench test was found to be a reliable, quick and easy, alternative test procedure to determine flexural strength (with plane of failure) parallel to the bed joints.