Collar-jointed Walls: An Assessment Of Their Performance And Buildability

Summary

The performance and ease of construction of collar-jointed brickwork and blockwork walls was assessed.  Collar-jointed walls, also termed double-leaf walls, are walls built from two separate leaves of masonry held together with stout wall  ties, with the gap between the leaves, the collar-joint, being filled with mortar.  Experience suggests that bricklayers find it difficult to fill this collar-joint fully with mortar.  An attempt was made to determine, for both brickwork and blockwork: whether it is possible to build a collar-jointed wall with the collar-joint fully filled; the effect an empty collar-joint has on the performance of a collar-jointed wall; and the relative performance of equivalent solid and collar-jointed walls.  A  full test programme was carried out to determine the relative performance of the different wall types.  It was shown that a collar-jointed wall can be built with a full collar-joint, and that there is a difference in performance between a filled and an unfilled collar-joint.  Differences were found between solid and collar-jointed walls.  For brickwork walls, bonded solid walls had the lowest failure load of the three sets of tests; for blockwork walls, solid 215 mm thick blocks have the highest failure load.  The results suggest that there may be reason to differentiate between the two unit materials.  2 refs.

Primary author(s): Ferguson W A

                            Building Research Establishment

Source: Masonry (9). Proc.6th Int.Masonry Conf.

            London,4-6 November 2002,p.157-162

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