Movement Joints In Concrete Walls

Change in wall height or thickness see figure 1 figure 2 change of loading see figure 3 abutments of walls and columns see figure 4 junctions of dissimiliar materials see figure 5.

Movement joints in concrete walls.

They are usually either cast or drilled into the concrete. In road construction movement joints can be provided in the transverse direction to allow the expansion and contraction of a concrete slab due to temperature and subgrade moisture variation. 4 recommends a contraction joint spacing of 30 times the wall thickness or 20 feet for an 8 inch thick wall 30 8 240 inches 20 feet. Some designers recommend re ducing joint spacings by about 20 in walls with frequent openings such as doors and windows.

Why do we need them. In reinforced walls and 6m in unreinforced walls. Contraction joints are usually about 0 25 inches wide and about 1 2 to 3 4 inch deep and are provided at intervals of not exceeding 30 feet. Movement joints such as control joints are one method used to relieve horizontal tensile stresses due to shrinkage of the concrete masonry units mortar and when used grout.

For tips on this check out bob harris s video or get a copy of his guide to stamped concrete joints are covered in chapter 23. Movement joints should not coincide with door or window openings due to the di culty in continuing. In concrete walls the movement joints should normally be placed at a maximum spacing of 7 5m. Movement joints are most commonly found between sections of building facades concrete slabs bridges pavements railway tracks pipelines and so on.

These are vertical joints or grooves formed or cut into the wall that allows the concrete to shrink without noticeable harm. A single row of short thick dowels provides reasonable shear transfer but suffer from deformation. Expansion joints allow independent movement between adjoining structural members minimizing cracking when such movements are restrained. Dowels are used to transfer shear across construction and movement joints in concrete.

Early entry saws make a nice clean cut for decorative concrete joints. Movement control aggregate concrete blocks position of movement joints consideration for the location of movement joints should be given at. It allows for thermal expansion and contraction without inducing stress into the system. Concrete expansion joints are used to separate slabs and concrete from other parts of the structure.

Expansion joints should normally be provided at a spacing of not more than 30m between successive expansion joints or between the end of the structure and the next expansion joint. Movement joint then a movement joint should be introduced into one of the two lengths or at the stagger as shown in diagram 4. Tial basement walls and the national ready mixed concrete association ref.