Expansion Joint Concrete Block Wall

Control joints are typically used in concrete masonry to reduce the occurrence of shrinkage related cracking.

Expansion joint concrete block wall.

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. National concrete masonry association 2014. Expansion joints are placed in concrete to prevent expansive cracks formed due to temperature change. Concrete joints are normally used to prevent cracks when the concrete shrinks by creating forming tooling sawing and placing joint formers.

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. This article emphases on need of expansion. 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. The pre planned cracks will provide a better finish concrete product and will be formed in specific locations where those cracks could be monitored.

Expansion joints are provided in slabs pavements buildings bridges sidewalks railway tracks piping systems ships and other structures. Details of this butt type con s t r uction joint are shown in figure 4. Standard specification for nonrigid vinyl chloride polymer and copolymer molding and extrusion compounds astm d2287 12. These joints will absorb the pressure created by the expansion by giving the masonry wall flexible space to expand.

The simplest vertical constru c t i o n joint is formed using a bulkhead b o a r d. Concrete blocks regardless of manufacturer will dry out and shrink slightly once the building is complete. S t r uction joint restricts wall move ments and should be as strong as the wall without joints. Concrete undergoes expansion due to high temperature when in a confined boundary which leads to cracks.

Joint sealants for concrete masonry walls tek 19 6a. 1 for more detailed information. 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.

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. Shrinkage cracks in concrete masonry are not a structural concern. Concrete joints are used to compensate when concrete expands or shrinks with changes in temperature. 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.

As mentioned in the expansion joints discussion the design of control joint spacing and location is the responsibility of the designer. National concrete masonry association 2009. If control joints are not provided a concrete masonry wall may crack as it shrinks over time.