Reinforcement

Blockwork will require bed-joint reinforcement above and below openings where it is inappropriate to divide the blockwork up into panels, with movement joints at the ends of the lintels. Bed-joint reinforcement would be inserted into two bed joints above and below such openings (Fig. 2.11). Cover to bed reinforcement should be at least 25 mm on the external faces and 13 mm on the internal faces. Combined vertical and horizontal reinforcement may be incorporated into hollow blockwork in accordance with BS 5628-2: 2000, where demanded by the calculated stresses. Typical situations would be within retaining basement walls, and large infill panels to a framed structure.

Fig. 2.10 Selection of bonding patterns for visual blockwork MOVEMENT CONTROL

Concrete blockwork is subject to greater movements than equivalent brickwork masonry. Therefore the location and form of the movement joints require greater design-detail consideration, to ensure that inevitable movements are directed to the required locations and do not cause unsightly stepped cracking or fracture of individual blocks. Blockwork walls over 6 m in length must be separated into a series of panels with movement-control joints at approximately 6 m centres. Ideally, such movement joints should be

Fig. 2.11 Reinforced blockwork

located at intersecting walls, or other points of structural discontinuity, such as columns. Additionally, movement joints are required at changes in thickness, height or loading of walls, above and below wall openings, and adjacent to movement joints in the adjoining structure (Fig. 2.12). Wall ties should allow for differential movement between the leaves in cavity construction and should be spaced at 900 mm horizontally and 450 mm vertically, for 50-75 mm cavities.

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