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MI-Roger 09-19-2009 05:29 PM

Crack filling concrete control joints
I crack-filled the control joints in my concrete drive today. When the concrete contractor poured the drive five years ago they saw cut the control joints pretty deep and they broke the rest of the way during the ensuing years.

Unfortunately; snow, ice, water, and freezing temps have cause the now individual slabs to heave and slightly separate during the winters, and not quite level out again in the Spring. I wanted to nip this in the bud so the slabs wouldn't tilt grossly as seen in some neighbor's drives.

Backer rod from Home Depot (although it would have been cheaper to buy it on-line) and three one quart tubes of NovaLink SL from CopperState Roofing's on-line store. (This stuff is made in Michigan, but the cheapest source is located in Arizona! Weird) I edged all the joints with Gorilla Tape before sealing so I wouldn't drip the self leveling sealant all over the concrete.

One bit of advise when others do this -
Remove the bordering tape after a couple of hours. Any sealant that is affixed to the tape and tears free will be re-absorbed by the still liquid stuff underneath. If I had waited until Monday evening (2-1/2 days) to remove the tape I would have had an ugly mess - and I thought I had been so careful applying the sealant.

The drive looks great! The NovaLink SL seemed easier to apply than the Sonalastic SL-1 I have used previously. Plus, it cures quicker! The NovaLink is tack free in 45 minutes whereas SL-1 requires 24 hours to become tack free.

SNC 09-19-2009 07:26 PM

sounds like your contractor skimped on the steel. I never ever place concrete with out steel, and in a slab i use both steel and wire.
i need to fill my expansion joints, the expansion material has dried up and shrank and its filling with dirt and the weeds grow.
no shifting, when i poured the different sections i pinned them togeather with 2' pieces of rebar every 2 foot oc

Termite 09-19-2009 10:41 PM

Nothing wrong with filling the expansion joints, but it must be done with a flexible material, never cementitious products.

stadry 09-20-2009 05:13 AM

its possible, but doubtful, unsealed jnts have allowed incompressibles to enter the jnt but the usual effect is spalling,,, at least your guy DID saw the jnts properly,,, i'd bet your problems due to water & soil rather'n anything else, tho,,, separation's due to movement & shrinkage more often than not.

closed cell backer rod is a std these days altho in the infancy of jnt sealing we used upholstery ' rope ' & denver foam rod,,, our experience was w/hot-poured (380-390f ) jet-fuel resistant | asphalt cement w/rubber | cold-applied ge & dow-corning silicone out of 55gal drums,,, tape on a highway ? ? ? not in my lifetime :laughing: nor any other contractor's since that'd double the crew size.

steel adds flexural strength ( bdge - hi-rise - driveway entrances for shock loading ) but no compressive strength,,, additionally, it should NOT be placed across jnts as it interferes w/slab expansion/contraction,,, wire mesh does add strength during tension ( ' green ' stage to solid ),,, after that, it holds the broken pcs together :whistling2: IF steel's used across hgwy jnts, etc, 1 end's greas'd to allow movement,,, those bars're typically epoxy coated & NEVER deformed,,, their purpose is to transfer load across the jnt - nothing else :thumbup:

MI-Roger 09-20-2009 02:28 PM

Joint Cleaning
I used a ragged old linoleum knife and a shop vac to snag all of the dirt, stones, and vegetation out of the joints prior to placing the backer rod and sealant.

Reinforcement is NEVER placed within 3 inches of the edge of a slab, and never from slab to slab (except for the transfer bars you mentioned)

I have learned to hate steel in concrete. Too often it is placed too close to an edge, or too shallow. Both will cause premature failure of the slab. Concrete w/o steel can be milled for surface repairs, overlays, or ultra-thin white toppings. Concrete w/ steel can only be removed and replaced. No steel, and small slab sizes (none of these 20 x 40 slabs some guys do) are my favorite.

Termite 09-20-2009 03:31 PM

[quote=MI-Roger;330071]I have learned to hate steel in concrete. quote]

You'd better learn to love the visible cracking and movement that will inevitably result.

stadry 09-20-2009 08:34 PM

'mite, i'm stickin' w/roger on this thread :yes: as it sounds like he's been 'round it a time or 2,,, once again, to reiterate, i repeat ' steel adds FLEXURAL strength ' - proper jnt pattern's the best way to prevent random cracking,,, any movement'll take place steel or not,,, welded wire mesh only holds the broken pieces together after the conc's cured.

jomama45 09-21-2009 10:25 PM

Sorry IRC, I completly agree with KC on this one. For the little extra money & effort involved, steel is always placed in ANY concrete I install, as well as adequate control joints. It may have quite a bit to do with climates also. We face a lot of frost & freeze/thaw cycles in WI. Ocaissionally we see major ground heave under concrete slabs. In these cases, the concrete containig rebar performs far superior than anything else when the ground thaws. The day we are placing rod baskets & greased dowels @ control joints in residential flatwork will be the day that I go back to school to get trained for a new career!:whistling2:

Termite 09-22-2009 12:08 AM

Supposed concrete gurus that argue against reinforcement just make me do this: :no:

(and for the record, I believe that properly placed control joints are equally critical)

MI-Roger 09-22-2009 05:40 AM

Job I had this summer..........
I was the PM, not the contractor:

Job involved a 5 lane wide, 4-1/2 mile circumferrence, circular test track for one of the auto manufacturers. The innermost lane is nearly flat and the outer lanes are sloped following a parabolic curve so that lane #5 is at a 30+ degree angle.

This track was constructed in the snowbelt during the 1960's using un-reinforced concrete, with NO expansion joints, and it is still in very good condition today!

Individual panels are one lane wide (varying from 12ft to 14ft-6in from inner to outer lanes) and 20 ft long. Panels use stainless steel (originally) dowel rods at ends for load transfer from panel to panel. The sides of each panel were formed with keyed joints to allow lane to lane sliding due to expansion.

The original theory, as related to me, is that the track would expand as a perfectly circular single monolithic structure, thus not requiring any expansion joints. Unbelieveable as it sounds, this worked perfectly for the first 30 years.

The owner is now experiencing random compressive failure at the ends of individual panels during extremely hot weather, primarily in the inner most lanes. My theory is that gravity is causing the outer lanes to slide down the embankment, thus placing additional compressive loads on the panels of the inner lanes.

This summer's job involved performing full depth/full width joint repairs in the inner lanes, as well as half width repairs, half depth repairs, and severe spalling repairs. The owner has also installed "Thrust Joints", which effectively are completely open 3-inch wide sections of missing pavement to absorb these compressive forces.

I tried to find photos of this job, but due to the fear of industrial espionage (and car magazine spys) cameras are only rarely permitted on this type of site.

I will continue to avoid placing reinforcing steel whenever possible. It makes future repairs much more difficult and costly, and often causes as many problems as it is intended to solve.

MI-Roger 09-22-2009 05:51 AM

A job two years ago.....
I was the PM, not the contractor:

We had to remove and replace a reinforced concrete U-shaped driveway in front of a company's head-quarters building in western New York. At time of initial construction, some knuckle-head had used stainless steel wire fabric as reinforcement, with only a 3-inch by 3-inch mesh size!

We had to beat the living crap out of the slabs to break them into pieces small enough to pass through the 3-inch openings! The reinforcement was still in perfect condition. No way was this stuff breaking apart. At least it had good scrap value. :)

The original installing contractor must have thought he was building a NATO air field.

stadry 09-22-2009 06:00 AM

believe me, that ' knuckle-head ' was NOT the conc contractor,,, speaking of which, do you know if abc & surianello're still in biz ? oak grove ? we work'd w/several during our time in ny,,, ever work w/for black river ? ? ?

ps - never saw a nato strip w/s-s wwf :no: next time, just saw it into slabs & let the recycling plant worry about the mesh

pps - 'mite, we'll just agree to disagree,,, have seen too much mesh in the wrong place,,, aci calls for it to be placed mid-point vertically in slabs - +/- 5%,,, in a 4" slab, that's only .1" - not possible

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