1 SHEAR CHARACTERISTIC OF INTERLOCKING MORTARLESS BLOCK MASONRY JOINTS Ahmed H. Alwathaf 1 , Waleed A. Thanoon 2 , Mohd Saleh Jaafar 2 , Jamaloddin Noorzaei 2 and Mohd Razali Abdul Kadir 2 1 Ph.D. Student, Faculty of Engineering, (UPM), 2 Associate Professor, Faculty of Engineering, Universiti Putra Malaysia (UPM) E-mail: walid@eng.upm.edu.my Abstract Recently, interlocking mortarless masonry system has been developed as an alternative to the conventional masonry system for wall construction. Shear characteristics in an interlocking mortarless block masonry system are yet to be investigated. As a matter of fact, there is no code provision or design guides available for the design of interlocking and mortarless wall system. This paper presents laboratory experiments on shear characteristics of the interlocking joints in mortarless masonry. Modified triplet tests on mortarless interlocking panels with different levels of axial compression were carried out to ascertain the deformation and shear strength characteristics of the system at the joint interface. Failure criterion for the interlocked bed joints under combined normal-shear load is proposed. Notation The following symbols are used in this paper: ı n Normal stress from pre-compression load. IJ u Shear strength of masonry joint. IJ o Shear strength at zero pre-compression stress (ı n = 0). μ Friction coefficient in joint interface.