There is an increased risk of cracking at changes in thickness loading and height.
Movement joints in concrete block 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.
Vertical separations are built into the wall at locations where stress concentrations may occur.
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.
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.
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.
An expansion joint in brickwork and blockwork is a means of solving potential problems caused by movement.
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.
The first movement joint should not be more than 3m.
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.
This movement could be a result of thermal expansion moisture movement creep and structural loading or the effect of chemical changes.
Ultralite insulite and dense concrete block walls should be divided into approximately 8 12m long panels for internal.
They are placed in concrete masonry walls to prevent cracking.
They are essentially vertical planes of weakness built into the wall to reduce restraint and permit longitudinal movement due to anticipated shrinkage and are located where stress concentrations may occur.
Movement control aggregate concrete blocks position of movement joints consideration for the location of movement joints should be given at.
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.
It is important to provide sufficient control joints so that the movement occurs at the joint rather that midway between the control joints.
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.
