Concrete joints are normally used to prevent cracks when the concrete shrinks by creating forming tooling sawing and placing joint formers.
Expansion joint concrete block wall.
As mentioned in the expansion joints discussion the design of control joint spacing and location is the responsibility of the designer.
The simplest vertical constru c t i o n joint is formed using a bulkhead b o a r d.
Joint sealants for concrete masonry walls tek 19 6a.
National concrete masonry association 2014.
The pre planned cracks will provide a better finish concrete product and will be formed in specific locations where those cracks could be monitored.
Thomas armstrong s technical guidance provides industry standard information on movement control on vertical and horizontal joints as well as concrete block wall ties in terms of spacing and positioning.
National concrete masonry association 2009.
These joints will absorb the pressure created by the expansion by giving the masonry wall flexible space to expand.
If control joints are not provided a concrete masonry wall may crack as it shrinks over time.
This article emphases on need of expansion.
Aggregate concrete blocks position of movement joints consideration for the location of movement joints should be given at.
This is unavoidable and perfectly natural for most construction products based on.
Concrete masonry banding details tek 5 2a ref.
1 for more detailed information.
Standard specification for nonrigid vinyl chloride polymer and copolymer molding and extrusion compounds astm d2287 12.
Shrinkage cracks in concrete masonry are not a structural concern.
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.
S t r uction joint restricts wall move ments and should be as strong as the wall without joints.
Expansion joints are provided in slabs pavements buildings bridges sidewalks railway tracks piping systems ships and other structures.
Control joints are typically required in exposed above grade concrete masonry walls where shrinkage cracking may detract from the appearance of the wall and to limit moisture or air infiltration.
Guidance for spacing and location of control joints can be found in the national concrete masonry association ncma tek note 10 02c control joints for concrete masonry walls empirical method 2010.
Expansion control joints to control the expansion and protect the wall structure from cracking under pressure masons install vertical control joints at specific locations.
Expansion joints are placed in concrete to prevent expansive cracks formed due to temperature change.
Concrete undergoes expansion due to high temperature when in a confined boundary which leads to cracks.
Concrete blocks regardless of manufacturer will dry out and shrink slightly once the building is complete.
Control joints are typically used in concrete masonry to reduce the occurrence of shrinkage related cracking.
Other constru c tion joints coincide with or function as contraction or expansion joints.
