Abode [ Improvements ] Guide to Concrete Restoration February 2007

by Jim Frazier
Images by Russell Byrne

Homeowners often make the choice to remodel or make additions to their residences. Jim provides some directions for the important choices and challenges that they thereby are called upon to face.

There’s an old saying in the building industry. “Three things are sure in life: death, taxes, and concrete cracks.”

Concrete lacks expansive qualities, so when it reaches its “breaking point” something has to give and the concrete cracks at that weakest place. In the best case, this weakest point is at a control joint – the tooled lines where cracking should take place.

Sometimes concrete cracks in inappropriate places, however, because there are not enough control joints or because these are not tooled deeply enough.

The controlled point depression should be a third of the depth of a slab. If necessary, after making a concrete repair we sometimes deepen joints with a concrete saw.

Cracks can be caused by improper preparation of the ground before the concrete was poured. A good example of this problem is in the road on the other side of the Sherman Island hotel. Twenty years ago they poured pavement on this road over a foundation of wood chips. It isn’t surprising that the concrete is now heaving and separating. It’s a miracle that it lasted this long.

Another cause of concrete cracks is improper drainage that causes soil to absorb water and expand. Concrete problems due to improper ground preparation are more common in higher-end custom homes than in less expensive developments and tract home projects. We always include “drainage swales” around a new home in order to maintain a required 2-percent grade that will move groundwater safely away from the buildings.

However, we have seen many property owners make subsequent landscaping decisions that introduce drainage problems and create unstable areas for whatever concrete patios, walkways, driveways, and pads that are subsequently installed.

Fixing Cracks
Ground must be stabilized before any repairs to cracks will be effective. Drainage problems can sometimes be fixed by installing a “French drain” around the area in order to wick the water away allowing the ground to stabilize itself as drying occurs and movement from sodden and expansive soils ceases.

Concrete repair is an excellent way to protect investment because cracks never get better over time. They only get worse. Repairing a crack will prevent water from seeping into the concrete and rusting out rebar, which can cause another whole series of problems requiring a much more expensive solution. In fact, once that happens, replacement is usually the only remedy.

I repair concrete cracks using a method called epoxy injection. Our repair is permanent. A pressurized epoxy injection is the only solution for cracked concrete. Everything else is a Band-Aid. Things like patching compounds simply will not hold over time.

I stumbled onto the process a decade ago while I was doing a construction job in Danville. I made the acquaintance a man undertaking concrete repairs in some nearby condominiums.

Six months later the man called me up and asked if he could show me the system. He demonstrated how his epoxy injection process worked. I copied the plans for his machine and built my own. In fact, I built three of them and am now working on five more.

We use the machine to inject low-viscosity epoxy into a crack, which creates a full-depth chemical weld of the concrete that, in most cases, results in a repair that is five times stronger than the original concrete. We cover the injected material with a cap seal in order to force the epoxy tightly into the crack

Epoxy is a high-strength resin with a fast curing rate. Epoxy injection is non-destructive and has been around for more than 30 years. It’s been approved by Caltrans as a method for repairing concrete bridge decks for years.

Now, thanks to our inexpensive machines, the method is available at reasonable cost for any property owner.

I’m a member of the International Concrete Repair Institute and have been convincing fellow members of the effectiveness of my epoxy injection remedy. Some members from the Northeast maintained that epoxy injection wouldn’t hold through the freeze-thaw cycles that concrete surfaces endure in that extreme climate.

I told them that I would guarantee that the freeze-thaw wouldn’t break the concrete that had been restored in this fashion. And I was right! Because the concrete itself would be destroyed before that epoxy weld would break.

I used epoxy injection to perform a major repair on the Mondovi Fountain at UC Davis. The workers had poured color concrete on a day that was too hot for the concrete to cure properly and almost immediately a series of enormous cracks developed, some as long as 180 feet.

The Project Manager invited me to come in like the Lone Ranger in order to save the day. If I failed then the contractor would be forced to tear out the whole fountain and start over.

The concrete in the fountain was a dark gray. Fortunately we were able to add color to the cap seal in order to exactly match the color of the surrounding material so the repair job wouldn’t end up looking like the fountain had contracted some disease. Nobody could tell that any repairs had been made. The engineers were very pleased with the results of the process.

I repaired the Eight Mile Bridge in Stockton for Caltrans. A large truck had smashed into one of the abutments creating a 10-foot crack. The job took us five hours, but probably spared Caltrans (and us taxpayers) a two-month project to replace the entire damaged abutment.

We often work for developers, who call us to fix slabs when they are planning to cover them with linoleum or tile. These floor coverings require a perfectly stable foundation so that cracks don’t come through the flooring.

Cosmetic Improvements for Concrete
We also do coatings, which are thin (1/4 to 3/8 inch) cementitious overlays that cover the existing concrete with high-coat polymers providing adhesive strength. We use muriatic acid in a concentration of one part acid to ten parts water to etch the surface and open pores to receive the coating.

Afterwards I neutralize the surface by washing it with a solution consisting of one part ammonia to ten parts water.

A coating is good for improving appearance but is not a permanent solution for cracks, which (once again) can only be repaired by the epoxy injection method described above before the overlay is put down. Coatings provide an appropriate solution for stained, pitted, or chipped concrete. It restores the appearance of sidewalks, driveways, patios, porches, and garage floors to like new conditions.

Coatings can also be thin-stamped with patterns to impose a design on the surface or to give the concrete a particular texture providing the illusion of stones or blocks. We can also hand-trawl the surface or give it a broom finish.

Concrete can also be restored to its natural color by applying Ardex Concrete Dressings, which can be walked on in just two hours and driven on in six.

For garage floors, we can use colored floors made out of epoxy. These are bullet proof but can be very expensive.

Acid stain or etching can be applied to concrete that’s in relatively good shape. Acid staining provides an illusion of depth and definition to a driveway.

Another kind of cosmetic effect can be added to the overlays from the large palette of available colors. You can give a wild look to your patio, for example, by painting it bright orange, or create a designer driveway that matches the color of your house – or the color of your Bugatti, if you live that kind of lifestyle.

For do-it-yourselfers, the biggest part of any of these jobs is preparation. For the overlay process, for example, I first pressure wash the whole area with a 4,000 p.s.i. Washer.

I attend seminars whenever I can so I can stay up on the new technologies and information and improve in my profession. I use Elite Crete Concrete Products; Steve Johnson is the local distributor. The company is located in Sacramento where the seminars are held. I took my whole crew for the training and it was worth the time and the expense.

Elite Crete conducts monthly seminars to train contractors and do-it-yourselfers in the things I’ve been describing. You can learn about the training at www.renewcrete.com/training.htm. °