1 Research Assistant, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, sciascan@mcmaster.ca
2 M.A.Sc. Candidate, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, joyalmp@mcmaster.ca
3 Joe Ng/JNE Consulting Chair in Design, Construction and Management in Infrastructure Renewal, Center for Effective Design of Structures, Department of Civil Engineering, Hamilton, ON, L8S 4L7, Canada, taitm@mcmaster.ca
4 Professor Emeritus, Centre for Effective Design of Structures, Department of Civil Engineering, Hamilton, ON, L8S 4L7, Canada, drysdale@mcmaster.ca
ABSTRACT
In order to produce concrete block construction capable of sustaining very high compressive strains without loss of compressive strength, a new block type, Self-Reinforced Concrete Block (SR Block), has been developed. These blocks utilize devices molded into the solid body of hollow block during manufacture. Under axial compression, these devices provide lateral confinement of the volume of block, bed joint mortar, and grout in the cells of the hollow block enclosed within the devices. As reported elsewhere [1], when tested in four-course high prisms, at strains slightly greater than found at failure of normal block prisms, the parts of the blocks external to the confining devices begin to spall off. The enhanced strength of the triaxially compressed volume within the devices result in no loss of prism capacity until strains several times larger than the normal crushing strain of concrete block masonry are reached. This behaviour allows masonry to achieve improved levels of ductility leading to economical design of reinforced masonry to withstand seismic loading.
When the capacity of the confined materials is utilized, the compressed masonry is left in a visibly damaged state due to the spalling of the unconfined part of the compression zone. This paper reports on research where previously tested prisms are repaired by casting new concrete/grout around the remaining confined volumes after any loose material has been removed. This simple and low-cost repair procedure restores the initial high stiffness of the concrete block masonry under compression to regain expected serviceable performance under service loads.
KEYWORDS: concrete block, confinement, ductility, masonry, repair, seismic performance
469.pdf
