National concrete masonry association 2014.
Expansion joint concrete block wall.
The pre planned cracks will provide a better finish concrete product and will be formed in specific locations where those cracks could be monitored.
The simplest vertical constru c t i o n joint is formed using a bulkhead b o a r d.
This article emphases on need of expansion.
Concrete blocks regardless of manufacturer will dry out and shrink slightly once the building is complete.
National concrete masonry association 2009.
Concrete joints are normally used to prevent cracks when the concrete shrinks by creating forming tooling sawing and placing joint formers.
Expansion joints are placed in concrete to prevent expansive cracks formed due to temperature change.
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.
Aggregate concrete blocks position of movement joints consideration for the location of movement joints should be given at.
Expansion joints are provided in slabs pavements buildings bridges sidewalks railway tracks piping systems ships and other structures.
Other constru c tion joints coincide with or function as contraction or expansion joints.
Standard specification for nonrigid vinyl chloride polymer and copolymer molding and extrusion compounds astm d2287 12.
As mentioned in the expansion joints discussion the design of control joint spacing and location is the responsibility of the designer.
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.
Concrete masonry banding details tek 5 2a ref.
These joints will absorb the pressure created by the expansion by giving the masonry wall flexible space to expand.
Details of this butt type con s t r uction joint are shown in figure 4.
If control joints are not provided a concrete masonry wall may crack as it shrinks over time.
Concrete undergoes expansion due to high temperature when in a confined boundary which leads to cracks.
Expansion control joints to control the expansion and protect the wall structure from cracking under pressure masons install vertical control joints at specific locations.
Shrinkage cracks in concrete masonry are not a structural concern.
1 for more detailed information.
Joint sealants for concrete masonry walls tek 19 6a.
S t r uction joint restricts wall move ments and should be as strong as the wall without joints.
It is a continuous vertical joint filled with mortar but with a bond breaker on one side so that tensile stress cannot develop across the joint.
Concrete joints are used to compensate when concrete expands or shrinks with changes in temperature.
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.
