Movement Joints In Concrete Block Walls

At corners consideration should be given to the effect of restraint and may require the first movement joint being positioned closer to the corner than the general rule of thumb suggests.

Movement joints in concrete block walls.

An information series from the national authority on concrete masonry technology control joints for concrete masonry walls empirical method tek 10 2c movement control 2010 introduction concrete masonry is a popular construction material because its inherent attributes satisfy the diverse needs of both exterior and interior walls. There is an increased risk of cracking at changes in thickness loading and height. Movement control aggregate concrete blocks position of movement joints consideration for the location of movement joints should be given at. It is important to provide sufficient control joints so that the movement occurs at the joint rather that midway between the control joints.

In practice providing that the length of an end wall between returns is not greater than the normal spacing of movement joints for the masonry material it should perform satisfactorily even when the rst. Control joints control joints are used to relieve horizontal tensile stresses due to shrinkage by reducing restraint and permitting movement to take place. The added resistance to movement afforded by the nearby intersecting wall at the corner causes cracking to appear in a stair step form following the mortar joints in the concrete block or brick whereas the same settlement or heaving forces might have caused more nearly vertical cracks if they had occurred closer to the center of the wall. The first movement joint should not be more than 3m.

This movement could be a result of thermal expansion moisture movement creep and structural loading or the effect of chemical changes. Each panel should be separated by a suitable vertical movement joint placed in an unobtrusive location note. 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. Greater distances between movement joints 9 m and sometimes longer are possible in aggregate concrete blockwork walls depending on the location and block type.

Block manufacturers should be consulted for guidance. Maximum horizontal spacing of control joints in unreinforced concrete masonry walls should be approximately 32 feet but a length spacing to height of wall ratio is a better measure. 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. They are placed in concrete masonry walls to prevent cracking.

An expansion joint in brickwork and blockwork is a means of solving potential problems caused by movement. Vertical separations are built into the wall at locations where stress concentrations may occur. In our concrete block wall crack photo shown below you can see both step cracks at the wall corner and a horizontal crack at the bottom of the upper 1 3 of.