re: Concrete expansion joint replacement question

I've used the expansion joint strips made by Quikrete with success (got them at Home Depot). They expand for a tight fit.

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Even with proper reinforcement it will crack unless you have a joint.

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I agree. All concrete is going to crack to some extent. However, if you reinforce it enough, you can keep the cracks to extremely small widths that are all but un-noticable. Driveways (and parking lots) are not typically reinforced like this. You're lucky if you have a layer of wire mesh somewhere down near the base.

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Without proper reinforcement, you DO need a joint, about every 12 feet max.

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You need contraction joints, but not expansion joints


Construction joints can be spaced up to 150' or something similar.

Also, there are reinforcement methods to make large slabs with no joints, and the cracks can be kept to near invisible size, but these methods require heavier reinforcing than is structurally required and it's expensive of course

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You need contraction joints, but not expansion joints

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Technically, I agree, but most people just refer to them as expansion joints.

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Construction joints can be spaced up to 150' or something similar.

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I agree, however that max distance is debatable.

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Also, there are reinforcement methods to make large slabs with no joints, and the cracks can be kept to near invisible size, but these methods require heavier reinforcing than is structurally required and it's expensive of course

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I agree, see my later post.

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Two different deals, both are required

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The only place your normal driveway may require an expansion joint is at the ends where it's against the house and the street

I don't think it will require any along its length, unless it's a really long driveway

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All concrete does not crack. Prevention of cracks is more a function of appropriate sub-grade prep, appropriate panel geometry and dimensions, correct concrete strength and adequate concrete depth than reinforcement. In a home driveway with appropriate sub-grade and panel depth and geometry, a driveway could need no primary or secondary reinforcement and never crack (with appropriate drainage and under normal residential traffic).

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I'm not saying you're wrong, but my professional experience building in SELA says otherwise.

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All concrete does not crack. Prevention of cracks is more a function of appropriate sub-grade prep, appropriate panel geometry and dimensions, correct concrete strength and adequate concrete depth than reinforcement. In a home driveway with appropriate sub-grade and panel depth and geometry, a driveway could need no primary or secondary reinforcement and never crack (with appropriate drainage and under normal residential traffic).

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And your wrong. All concrete cracks no matter what you do especially with large areas like a driveway. The entire point of a dummy joint is to control where the crack is and how it looks, that is 100% of the reasoning behind dummy joints. Expansion joints(true expansion joints made out of either fiber board or rubber) are to help elevate the stresses of concrete swelling and shrinking due to temperature changes.

ALDOT specs out on curb and gutter and sidewalk to have expansion joints every 80' on center, most cities spec it at 20' on centers. There is no spec on driveways since DOT and cities don't usually hire on contractors to install driveway since it isn't on their right of way. Driveway turnouts and inlets are supposed to have expansion joints 20' away from them.

Aesthetically on slabs on concrete, and the typical design, is to put dummy joints on squares. So if you have 5' wide sidewalk, put dummy joints 5' on center. 4' on center for 4' sidewalk and so on. Dummy joints are also typically specced to be 1/4 the depth of the concrete to ensure that the concrete cracks there so a slab that is 4" thick would have a dummy joint that is an inch deep which usually requires coming back with a saw and cutting them after too.

I own a concrete company and have taken a lot of concrete seminars so I do know my concrete.

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Wrong.

All concrete does not crack.

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No, you are wrong. I can probably round up 30 references citing this in the next 5 minutes. I challenge you to find me any reputable documentation saying that concrete DOES NOT crack.

Backer rod and self leveling joint sealant is the way to go. Make sure you get all of the old materials out of the joint and clean the sides of the concrete before applying the new joint sealant. Use a wire brush and make sure it is clean so the new joint sealant will adhere to the concrete.

Like the other poster said, CMC on Highland Rd will have everything you need. They have the backer rod and self leveling joint sealant.