Filling Expansion Joints on Concrete Floors for a Smooth, Easy to Clean Finish

by Cornell University Library

Expansion joints are placed in floors to allow for shrinkage as concrete cracks as it cures. The joints are often trawled into the floor or occasionally cut after the floor is hard enough to walk on. During the curing phase of the floor these joints often develop cracks that go to the bottom of the sand or gravel base below. If you try to fill these cracks with a liquid it often leaks out the bottom leaving the joint open again before the product is set up.

In some cases it is best to leave expansion joints. Temperature changes force concrete to expand and contract. Joints cut in sidewalks are designed to allow for expansion and contraction without cracking. For most interior applications expansion and contraction is not very severe. The covered areas allow for slower temperature changes and most interior spaces are climate controlled to some degree. Food processors and other operations that have health concerns usually fill expansion joints to avoid associated cleanliness issues regarding mold, mildew and insect problems that the joints can promote.


Durall has developed an expansion joint grout that can quickly fill these joints to level without the danger of it leaking from the bottom. In addition, the grout is extremely hard, cures rapidly and has excellent adhesion properties when applied to cleaned and prepped floor joints.

First, clean your floor with a high alkaline cleaner to raise the pH level to around 12 using an aggressive scrubbing brush with a rotary scrubber. Follow the alkaline cleaner with an acidic cleaner pulling the pH down to 4 and scrub rinse once or twice with water being sure to clean the joints as you go. Often using the pressure from a water hose during each phase will blast dirt out of your joints. Next, mix up Durall’s grout with gloves and take a hand full and scrub into the joints at a 45-degree angle. Use a putty knife to remove excess material and smooth the top of the grout even with your floor. Allow at least two hours to cure. After the grout hardens it is often helpful to scrub your joints again with fresh water to remove any residue left from your scrubbing process. You will still see the joints but they will be smooth, hard and level. With a coat of epoxy or urethane the newly coated surface will look great with a minimum of wearing.

Durall Industrial Flooring supplies kits of materials that are customized to owner specification and delivered directly to the job site. Kits include complete application instructions and 24/7 help lines staffed by seasoned flooring experts so professionals and amateurs alike can successfully install a quality floor.

Web visitors can obtain free, job-specific quotes on materials or nationwide turnkey installations by completing a simple questionnaire at

For a high-resolution photo example, visit:

For more information, contact Harvey Chichester at:

Phone: 1-800-466-8910 or 952-888-1488 (24/7)


Harvey Chichester is a principal of Durall Industrial Flooring, a company with more than 40 years experience in developing special flow-coatings for industrial and residential floors. Automotive and shopping centers, breweries, food processing plants, manufacturing plants, airplane hangars, car washes, kennels, warehouses, printing plants, residential basements, pool decks, and condominiums are among some of the facilities in which he has installed floors. http:\

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