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Spall Repair of Control Joints in Floor Slab

  • 1.  Spall Repair of Control Joints in Floor Slab

    Posted 10-17-2018 01:24 PM
    Edited by Thomas Halmi 11-01-2018 11:33 AM
      |   view attached
    I am looking for repair suggestions as well as possible cause of spalling of control joints in a concrete floor in a factory.  Spalling is occuring at nearly all of the joints in the aisles only.  The concrete is 6" thick 4000 psi concrete, with welded wire fabric reinforcement at 3" depth,  with metal hardener, approx. 18 years old. Spalling started several years ago, and has become more of a problem lately.Things that have changed in the last two years: increased sweeper/scrubber activity in the aisles (water only, no cleaning chemicals), weekly polishing of the concrete surface (with HTC twister diamond pads.  The concrete floor is subjected to solid tire forklift traffic and tugger and dollie traffic.  Aisles cannot be shut down to traffic longer than a day for repairs. Thanks in advance to any advice and experience with this.

    Update: Thanks for the suggestions so far.  The slab has not curled.  There are some crazing areas in the slabs.  The floor has been in use many years without issue.  Only in the last couple of years has this spalling started.  The only areas showing an issue is where the floor is scrubbed several time daily with a sweeper scrubber unit (Tennant), the frequency of which increased dramatically in the last two years.  Bi-weekly the plant also polishes the aisles with a diamond pad.  Could the metal hardener be getting water (no urethane concrete sealer anymore due to the polishing) and more water at the joints and causing the metal hardener to corrode thus creating the spalls?  Does this warrant a core/petrography to see if this is occuring?  Would a rigid epoxy mortar repair be a suggested solution after sawcutting and removing 1/2" to 3/4" of the spalling material, then re-establishing the joint with a sawcut and filling with a polyurea?

    Final Update:  I will likely go with the following repair method: http://metzgermcguire.com/wp-content/uploads/2012/02/AH-Joint-Rebuild-2013.pdf
    1. Sawcut damage limits behind spalls
    2. Chip out damaged/spalling material
    3. Clean and prime the joint area
    4. Fill the joint with Armor-Hard material
    5. Trowel flush, cure
    6. Flush grind surface
    7. Sawcut new joint over location of the old joint
    8. Fill new joint with polyurea

    Thanks for everyone's input.

    Thomas Halmi P.E., M.ASCE
    Senior Facilities Engineer
    Belmont MI
    (616) 866-8863

  • 2.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 07:48 AM
    Edited by Tirza Austin 10-18-2018 07:48 AM
    ​One possible cause is if the slab edges have curled up (if so it probably occurred as the slab dried ~18 years ago), resulting in the joints being the high spots in the floor. Put a level across the joints to check for this. If the slab edges are curled up then the sweeping/scrubbing/polishing and lift/dolly traffic and dragging items over the joint is just wearing down the high spots. Any kind of patch probably wouldn't last long since you would be just building up the high spots again. It would make more sense to grind the slab down in these areas.

    Kelly Covert, P.E.
    Klepper, Hahn & Hyatt
    East Syracuse, NY 13057
    (315) 446-9201

  • 3.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 10:10 AM
    Edited by Tirza Austin 10-18-2018 10:10 AM
    The damage is very likely due to the impact of harder tires or smaller diameter wheels as they cross the joints.

    Glenn Boerke P.E., M.ASCE
    Smyrna TN
    (615) 223-7120

  • 4.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 10:13 AM
    Edited by Tirza Austin 10-18-2018 10:12 AM
    ​Curling was one of my first thoughts too - not uncommon.  I also agree with the comment about grinding down high spots if it's curled; ditto for the thought that repairs (at least thinner ones) won't hold up well where there's heavy lift truck traffic.

    Heavy lift truck traffic will tend to damage the joint areas both due to the curling issue (if present) as well as lack of support at the joint edge.  Some facility managers prefer epoxy joint fillers on interior floor slabs with heavy lift truck traffic - it provides better support to the joint edges than flexible sealants. 

    Greg Thein, PE
    Cleveland, OH

  • 5.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 11:41 AM
    Edited by Tirza Austin 10-18-2018 11:40 AM
    ​I concur with Kelly that the most likely cause for the edge spalling is curling of the slab. If the slab is curling, grinding the slab along the edge would be appropriate. If the curling is significant, I would also recommend injecting grout under the slab along the joint to fill the voids that would have occurred as the edges of the slab curled.

    Brian Kehoe P.E., S.E., F.ASCE
    Associate Principal
    Wiss, Janney, Elstner Associates, Inc.
    Emeryville, CA
    (510) 428-2907

  • 6.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-19-2018 12:14 PM
    Could it be due to differential deflection, between two sides of joint, due to LL as wheels with heavy load cross the joint?

    Neil Kazen, M.Eng., M.Sc., P.Eng.
    Retired Structural Engineering Manager, Transportation Division, SNC-Lavalin
    Toronto, Ontario, Canada

  • 7.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 10:12 AM
    Edited by Tirza Austin 10-18-2018 10:11 AM
    In the is past when we have seen this occurrence, there is usually movement in the slab at the joint under the fork lift traffic.  The constant "pumping" of the slab is driving the soils up through the joint and are being cleaned away with the constant cleaning of the floors.  As time progresses the slabs pump more, pulverizing the soils underneath and driving more soils out through the joint.  We have had good results with pressure grouting the void areas under the joint.  Expanding foam injection may be a good alternative also.

    Gary Barnes P.E., M.ASCE
    G B Engineering, PLLC
    Charlotte NC

  • 8.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 01:38 PM
    Edited by Tirza Austin 10-18-2018 01:38 PM
    I have successfully used a product called "Delcrete" for pavement repair. It is expensive, but cures very quickly and holds up well.

    Stacey Morris P.E., M.ASCE
    ETI Corporation
    West Memphis AR
    (901) 758-0400

  • 9.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 06:36 PM
    Edited by Tirza Austin 10-18-2018 06:35 PM
    Here's a few suggestions regarding slab in-control joint spalling. Since you are operating heavy duty machines  and the concrete strength is only 4000 Psi, the slab might have curled. It's an old concrete pour, might not expend further significantly. Use high early mix Quickret. It provides up to 2000 Psi strength in one day. Make sure to fill all the control joints but leave one joint open in case of extreme expansion. 

    Second, change driveway direction as the forklift runs parallel to the controls joint and that's a way to prevent spalling of the slab edges.

    Sayed Maqsood S.M.ASCE

    Oakland CA

  • 10.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-18-2018 10:48 PM
    Edited by Tirza Austin 10-18-2018 10:48 PM

    The hard wheeled traffic over a joint without steel armoring is usually the reason that concrete spalls, especially 4,000 psi concrete with hardener applied.  I would suggest repairing with BASF MasterEmaco T545 is temperatures are less than 85 degrees at the location.  If higher temperatures then use T54HT but it shouldn't be necessary in a factory.  This is a one-component magnesium phosphate based mortar and will reach 5,000 psi in 3 hours.  Be careful as it really sets fast and is difficult to finish if you delay much.  The strength in one day will be 6,000 psi.  Just follow the instructions for placement and the website has good information.

    Also, a great joint filler has been Metzger-McGuire's MM-80.  They also make a product which is a two-part Polyurea which is Spal-Pro RS 88 but I have not found it to be the best for heavy spalls.  Let me know if you need further information.

    Andrew Bowser, P.E.
    TEAM Group, Ltd.
    Euless, TX 76053
    (817) 545-1515

    Andrew Bowser P.E., M.ASCE
    Euless TX
    (817) 545-1515

  • 11.  RE: Spall Repair of Control Joints in Floor Slab
    Best Answer

    Posted 10-19-2018 11:21 AM
    Edited by Thomas Halmi 11-01-2018 11:13 AM
    The spalling is likely due to lack of an adequate joint filler when originally constructed.  Sawed control joints should be filled after the slabs have cured and before being put into use, especially with hard-wheeled trucks.  Now retired, I am not up-to-speed on the latest materials.  Years ago we spec'd elastomeric caulks (polysulfides?), today there are epoxies to do the job.  Whatever is used should be fairly hard and durable to offer long-term support of the edges of the joint.  I defer to others in the discussion on repair method and alternatives, but stress the importance of the original filling of the joints.

    Richard Lenz P.E., Life M.ASCE
    West Chester OH
    (513) 777-5525

  • 12.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-22-2018 01:29 PM
    Edited by Tirza Austin 10-22-2018 01:29 PM
    Dear All:

    I appreciate all the suggestions and thoughts.  There is no joint curling or pumping.  The spalls started appearing in recent history of the slabs.  There is some crazing, but I don't think this contributed to the problem.

    I am thinking the spalling started after:
    1.  The plant began burnishing/polishing the floor, bi-weekly.
    2.  The plant increased the frequency of floor scrubbing (water being applied).
    3.  Increased the usage of tuggers and small hard wheeled carts.

    There wasn't any sealing of the joints after construction, which was an additional factor.

    Has anyone had experience with water causing the metal hardener to rust, then creating a spall?

    Thank you,

    Thomas Halmi P.E., M.ASCE
    Senior Facilities Engineer
    Belmont MI
    (616) 866-8863

  • 13.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-23-2018 10:02 AM
    Edited by Tirza Austin 10-23-2018 10:01 AM
    One possible culprit you alluded to might be the type of wheels on the vehicles used on the floor slab. If pneumatic (soft) wheels or lighter vehicles have been used in the past, and that has changed to hard wheels or heavier equipment, this might lead to more spalling of joints. There are two design issues to consider when slab joints are subject to heavy, hard wheeled traffic. One is a smooth transition across the joint, no edge curling, and usually a joint filler (consider semi-rigid epoxy). The second is shear transfer across the joint. As the vehicle loads move across the joint, the load is transferred from one slab section to the other. Industrial slabs usually have shear transfer devices installed such as dowels or shear plates. If you only have saw-cut joints, the only mechanism for shear transfer is the aggregate interlock between slab sections. One could speculate that as a slab shrinks, the aggregate interlock would lessen as the gap gets wider. I don't have experience with joint repairs, or installation of shear transfer devices after the fact. Perhaps someone else could chime in on this.

    Gregory Wayland P.E., M.ASCE
    Gainesville FL

  • 14.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-24-2018 10:08 AM
    Edited by Tirza Austin 10-24-2018 10:07 AM
    ​Regarding metal hardener rusting - some are sold as non-rusting/non-corroding.  You'd have to determine what type of hardener was used to determine if corrosion of the hardener is contributing to the problem.

    Regarding your three other potential issues (weekly burnishing/polishing, increased wet scrubbing, and increased usage of tuggers and small hard-wheeled carts), I'd suggest running an experiment (if possible) eliminating one of those variables in an area for a month to see if there is a noticeable difference.  I'd be interested in the results.

    Regarding joint fillers - I think a hard filler like an epoxy is required for fork traffic and supporting the edges of slabs.  Soft flexible fillers are great for handling expansion and contraction and for sealing against water intrusion.  But in the case of an indoor slab, expansion and contraction should be minimal and a hard filler may be more appropriate for structurally supporting unsupported slab edges (ie. at joints).

    One other possibility........the slab problems may be God's way of punishing Steelcase for promoting open office plans...

    Greg Thein, PE
    Cleveland, OH

  • 15.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-23-2018 08:09 AM
    Edited by Tirza Austin 10-23-2018 08:09 AM
    I would tend to concurr with Richard, for saw-cutting the joint, for developing a physical joint width of say 20mm on each side, and filling the same with elastic filler, with low-cost Bitumen, and little higher cost Polyurethene, OR if your Clients can afford, for a long time performance, use filler of Octyl based Silicon. A cheaper variety of Silicone Sealant, as an option, could be Methyl based Silicone Sealant.

    This will allow, differential settlement, at Junctions of hard-wheeled traffic, and the areas on both sides of the same. This will also ensure that Wash/Scrubbing Water, will not get to the sub-grade, otherwise tending to soften/reduce load bearing capacity of the underlay.

    Consulting Structural ENGINEER

  • 16.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-24-2018 12:32 PM
    Edited by Tirza Austin 10-24-2018 12:32 PM
    Sixty years ago the Portland Cement Association recommendation was to fill the new joints in aisles with strips of lead and peen the surfaces to make them flush with the floor. I suppose that would not be environmentally acceptable now, but the principle was to firmly support the edges subject to steel wheel traffic. Any current materials that would provide full support should be installed before traffic starts, or as soon as repairs are completed. I'm not sure if floor joints are taken into consideration when equipment is selected.

    Richard Albright P.E., F.ASCE, F.SEI
    Consulting Engr
    Indianapolis IN
    (317) 846-5546

  • 17.  RE: Spall Repair of Control Joints in Floor Slab

    Posted 10-24-2018 05:02 PM
    Edited by Tirza Austin 10-24-2018 05:02 PM
    You mentioned increased washing of floors where spalling is occurring. Perhaps water is seeping down to the soil at the joints, weakening the soil and causing more differential movement of the slab when wheels roll across the joint, thus causing the spalling?


    Robert Bucelwicz PE
    Needham MA