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The mystery of a round arris

October, 29, 2018

We at Peikko have two major Floor Expansion Joints in our offering – TERAJOINT® and OPTIMAJOINT®. Both floor joints serve the same purpose: transferring loads over a controlled shrinking line. There are some differences, however. TERAJOINT® has sharp 90-degree edges in the top strip facing the concrete, whereas OPTIMAJOINT® has a round arris towards the opening. What is good about a round arris in a floor joint top strip?

I once had a chance to sit down with Pat Eve from Leo Consultants Ltd, just for few evening beers after a meeting and took up this topic. Pat Eve is the Consultant Technical Director of Concrete Floor Products Ltd., and also the person who designed OPTIMAJOINT®.

“You are right, they are different,” he started. “You know, TERAJOINT® is still one of the best floor joints in the market for moderate openings of the joint – and it is not bad for greater, 20 mm openings, either.”

“Yes, I know, I’ve been told that sharp edges do not crack the concrete facing the floor joint, and that’s why we use special steel strips to create this sharp edge. But… then why does OPTIMAJOINT® have a different approach?”

“You see, the development in ground bearing slabs is going towards the use of better quality concrete, which enables super flat floors. There are different additives, ceramic fibers, steel fibers etc., and compression strength can be higher than 10 years ago.”

“Yes, ok, but what does this have to do with that round arris?” I asked.

“Wait a minute,” he said and cleared his throat. “This modern flooring concrete tends to shrink more, so even with shorter spacing of floor joints, openings tend to be larger, 20 mm easily, or even bit more. “

“And?” I asked, wondering if I’m going to like the argumentation or not.

“Think about a warehouse or a logistics center that uses robot forklifts – or just normal forklifts. When they drive on the floor, they cross the floor joints dozens of times every day. Every time they cross the floor joint, the tire drops a half or full millimeter and hits the top strip on the other side of the floor joint. A sharp edge in the floor joint will cut a microscopic piece of rubber off from the tire every time.”

“Ok, understood – but what happens then with the round arris of OPTIMAJOINT®?”

“OPTIMAJOINT® is a bit gentler to tires. When the tire drops that half a millimeter and hits the top strip on the other side of joint, it faces not a sharp but a round surface, feels the bump but does not lose any rubber in that interaction. As a result, forklift tires last a little longer.”

“So, that is the reason,” I said. “I think I got the point. I have understood that forklift tires are not cheap, especially in those warehouse robots. Every little thing helps in the lifecycle costs of a logistics center or a warehouse. Thanks for enlightening me!”


Interested in OPTIMAJOINT®?

Read more or watch our video.  

Petri Suur-Askola

Petri Suur-Askola works now as a Business Director for Connections. Pete started in Peikko 2006 to build up a Lifting Systems offering, and has been in different duties in Product Management and R&D. He has M.Sc degree in Civil Engineering from Technical University of Tampere and just finalized eMBA degree from Lappeeranta University of Technology. Pete’s working history includes precast project engineering in Singapore, Dry Mortar plant technology and projects around the world as well as short leap to plastic molding business for mobile phone business before Peikko. Pete has patented couple of features together with his colleagues for wire loop boxes relating to vertical joint connections of walls. His approach to construction, both technology and business, is more practical and effective than scientific.  

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