Concrete placed without joints is susceptible to uneven cracks.
Concrete joints are an important part of any concrete masonry project, as they help compensate when concrete expands or shrinks due to changes in temperature. Without them, cracks can form in the surface of the concrete. Concrete joints help prevent these cracks and provide a more finished concrete product. Cracks that do form will occur in specific locations that can be easily monitored for repair.
Contraction Joints
Concrete contraction joints help during cold conditions. They create a weakened area in the concrete to regulate where cracks will occur — typically in a straight line. Contraction joints can be tooled into the surface at the time of placement or sawed into the hardened concrete surface thereafter. These joints should never exceed a length to width ratio of 1 ½ to 1, and are typically spaced at distances equal to 24-30 times the slab thickness. Load transfer devices are necessary for joint spacing greater than 15 feet.
Expansion Joints
Concrete expansion joints separate the flat slabs from other parts of the structure. They allow for independent movement between adjoining structural members, thus minimizing the crack when those movements are restrained. During hot weather, this will allow for the thermal expansion of the concrete.
Why Concrete Joints are Important
When two consecutive placements of concrete meet, a construction joint is needed. The weakest portion of the concrete surface is always the first to crack, and a concrete joint fixes this liability by putting the pressure on the joints instead. A certified structural engineer designs and specifies construction joints to ensure that they are placed correctly.
Masonry Repair and Restoration from Del Prete Masonry
For all of your questions regarding masonry repair and restoration, feel free to contact Del Prete Masonry. Our masonry restoration professionals have the experience and history of satisfied clients to prove that we’ll get the job done right, and cost-effectively. To get started with your masonry restoration project, please contact our office today at 410-683-0650 or email us at mike@delpretemasonry.com. We serve Baltimore City, County, Harford County, Carroll County, Anne Arundel County, and Howard County.
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Tags: Concrete, construction joints