Full depth crack repair in warehouse floors usually involves cutting open the cracks with dry diamond saws. This is a slow process and creates a lot of hazardous silica dust that needs to be mitigated. Repair contractors at an Amazon Warehouse project are using an innovative way to repair cracks in the floor without the traditional cut and fill methods.
Some people question why these types of cracks should be repaired. Cracked floors in industrial and commercial settings are a liability. The cracks will continue to get larger as wheeled traffic starts to crush the sidewalls. (More) Cracks will also fill with dirt and debris creating a hard to clean surface. Roadware 10 Minute Concrete Mender™ is a structural polyurethane that will restore load transfer and can bring a floor back to original serviceability.
This three level Amazon Warehouse developed thousands of linear feet of shrinkage cracks prior to being places into service. Roadware 10 Minute Concrete Mender will be used to repair them.
Use sacrificial vinyl weatherstrip to make a dam parallel to the cracks that will hold Roadware 10 Minute Concrete Mender™ in place while it soaks down into the cracks. Concrete Mender™ is nearly water thin when mixed and will flow easily deep into open cracks. Since Concrete Mender™ will start to gel up in 5-7 minutes, it will naturally self-seal the bottom of the crack as it cures. It sometimes takes three of four light pours of material, but it will fill the crack completely and start the structural Microdoweling™ process. Microdoweling™ is how Concrete Mender™ uses low surface tension and molecular attraction to penetrate concrete surfaces and locking into the aggregate and rock matrix.
With Concrete Mender™, expensive pumps and equipment is not needed. Once cracks are vacuumed and the surface is cleaned. The weatherstrip dam can be applied. Roadware 10 Minute Concrete Mender™ can be mixed on one gallon batches by hand in a bucket and poured directly into the cracks. Additional manufactured sand can be added for larger cracks, but it is not recommended for this type of repair. See more here: Concrete Mender Bulk Application Instructions
When the Concrete Mender™ cures in about 10 Minutes at 72 degrees F (21C) , the weather stripping and excess material can be shaved clear or ground smooth with standard equipment.
After buffing and clearing excess material, floors can be returned to service immediately.
Finished concrete crack repair blend in nicely at an Amazon warehouse using full depth Roadware 10 Minute Concrete Mender™.
Additional buffing and service traffic will blend the repairs even more into the surrounding concrete.
Roadware 10 Minute Concrete Mender Technical Data Sheet
For many years, engineers have looked for ways to fully inject repair polymers into cracked concrete structures. The general consensus is to seal off the crack with a sacrificial epoxy and install injection ports every few inches. Then thick epoxy is injected under high pressure into the crack with expensive resin injection pumps. The process is time-consuming, the epoxy is brittle, the equipment is expensive and the skill level is highly specialized. This makes epoxy injection slow, expensive and not really effective in the field.
At Roadware, we look for ways to make concrete repair fast, effective and easy.
Fast is better. When injecting Roadware 10 Minute Concrete Mender into concrete, the fast gel and cure time allows you to make a full depth repair from the bottom of the crack up to the top. If the crack you are injecting has a large hidden void, Concrete Mender repairs will start to gel and plug up the void in several minutes. Injection epoxy that takes several hours to cure will sink to the bottom of your crack and pool in the base before it has a chance to cure.
Effective. Concrete Mender is a Structural Polyurethane**. It is about as hard as typical concrete with much greater tensile and bonding strength. It is super thin at 8cps with a surface tension 1/3 of water. It can to penetrate concrete cracks and surfaces. Concrete Mender does not need to be forced into cracks with high pressure pumps and extraordinary methods. Concrete Mender can easily flow into cracks and fissures with just simple manual tools and a specially designed application mixer. You can repair more cracks in less time with less waste then ever before. Repairs are structural in nature and will move with the concrete, not against it like very hard epoxies.
Easy Application. For a repair to be effective in the field, it has to be simple enough for crews to apply efficiently. Installation productivity saves money.
To start, simply drill a 3/8″ diameter hole about one inch deep into the crack at several points along the crack. Clean the crack and holes with a vacuum.* (Click here to learn how to work safely around silica dust).
Tape off the top of the crack and around the holes you just drilled with clear duct tape or Gorilla Clear Repair Tape. These tapes have a good adhesive that will stick to the surrounding concrete. Do not use packing tape or other tapes without testing them first.
Gently squeeze the handle of the gun and slowly inject Concrete Mender into the crack. Work product into several holes at a time, moving the cartridge back and forth among them. Allow time for the Concrete Mender to start gelling in the bottom of the crack. As the crack starts to fill completely, you will see Concrete Mender flow under the clear tape from one drilled hole to the other. You may see air bubbling up from one hole as you inject Concrete Mender into adjacent holes.
Once the crack is filled to refusal, move on to the next few drilled holes until the whole crack is filled.
After 10 minutes at 70 degrees or 23 C, pull the tape. You can use a razor scraper, grinder or polishing device to remove and excess material and blend in the repair.
Using Roadware 10 Minute Concrete Mender and Soft-tip injection mixers, you can structurally repair concrete cracks and delaminations with simple tools and methods. This unique system saves time and money and allow for a high production rate for installers. The drill hole/inject method is much less invasive than traditional cut and fill methods and creates a lot less silica dust on the jobsite. The Microdoweling properties of Concrete Mender and Soft-tip Injection promises to be a winning combination for tough concrete repair challenges.
1006-STR 24-element static mixer with Easy Injection Tip
1006-STR 24-element static mixer with Easy Injection Tip
*“Workers may be exposed to dangerous levels of silica dust when cutting, drilling, grinding, or otherwise disturbing materials that contain silica. These materials and tasks are common on construction jobs. Breathing that dust can lead to serious, often fatal illnesses.” The Center for Construction Research and Training. Click here to learn how to work safely with silica.
** Structural Polyurethane: A polyurethane based material that restores structural integrity and aggregate interlock to distressed concrete by using low surface tension and low viscosity to penetrate concrete surfaces and cross-linking polymer chains to bond directly to the concrete-aggregate matrix. This bonding action utilizes capillary forces to self-inject polymer chains into the surrounding concrete. This material should have a modulus of elasticity less than the surrounding concrete and should not become brittle over time. This material may be combined with manufactured sand to form a PCC compatible polymer concrete that can structurally repair concrete cracks and spalls.
Last week I posed two new videos on the Roadware YouTube Channel showing Roadware MatchCrete™ Clear in action repairing cracks in an exposed aggregate concrete sidewalk and patio. I also posed a video on how to repair a hairline crack in a driveway or sidewalk.How to repair a crack in an exposed aggregate concrete patio using Roadware MatchCrete™ Clear in a 600ml cartridge.
One of the most common calls we get is asking how to repair a crack in a driveway or patio. We designed Roadware MatchCrete™ Clear with this in mind. Roadware MatchCrete™ Clear is a UV stable clear polyurethane hybrid that makes effective repairs to most exterior concrete surfaces. By simply leaving the repair clear, the color of the surrounding concrete shows throughout the repair.
The first step to a good looking crack repair is to rout-out or cut the repair open with a diamond blade grinder. You only have to go about 1/4″ x 1/4″. This will create a recess for the material to rest as it soaks down further into the crack. Skipping this step will allow the material to flow uncontrollably on the surface and will create a messy looking repair.
Apply cartridge mixed MatchCrete™ Clear directly to the crack. Small amounts of silica or quartz sand can be added to keep the material from flowing out the bottom of the slab. If necessary, matching colored sand can be used to match colored concrete areas. Fill the crack to slightly below grade to prevent material from flowing on to the surface of the concrete.
After a year of service, the repair above still looks good. Please note, MatchCrete™ Clear is not a soft expansion joint material and should not be used in joints that are designed to move. Always give careful consideration as to why the concrete cracked in the first place and what the concrete is expected to do in the future before making repairs of this nature.
We have a new video for driveway hairline crack repair: