How to install expansion joints in concrete like a pro
Expansion joints in concrete and masonry flatwork are similar to building movement joints but smaller in scale and simpler to build.
The picture below shows a 1″ wide expansion joint in an upside down T shape next to a quarter inch saw-cut control joint.
Concrete will naturally crack, but the control joint allows concrete to crack in a controlled manner where it will in almost all cases follow the rectalinear lines of the saw cut. By comparison the expansion joint is much wider and set with a set with a polypropylene or tar impregnated homasote or asphalt saturated layered mineral filler board.
In this case, the expansion board is covered with a struck elastomeric sealant.
