Epoxy Injection – Minimum Crack Size

April 19, 2010

How Small a Crack in Concrete Can Be Epoxy Injected?

Norm:
Typically a crack that is 30 or 35 mils or larger (about 1/32 inch) can be epoxy injected. You can get into even smaller cracks under the right conditions with Epoxy.com Product #308 Ultra Low Viscosity Injection Resin for Load Bearing Applications an Ultra-Low Visocosity Epoxy Resin System for use as epoxy injection or low viscosity epoxy mortar resin. It is 100% solids and is mixed 2:1 by volume. Meets or exceeds the requirements for ASTM C881 Types I and IV, Grade 1, Classes B &C. Learn more on the Epoxy.com Website or contact Epoxy.com Technical Support by email or call 352-533-2167.

One of the most versatile, problem solving products available in epoxy systems today is Epoxy Injection Resin. Structural restoration of concrete by epoxy injection is very often the only alternative to complete replacement. It therefore results in large cost savings. Injection protects the rebar and stops water leakage.

Epoxy Injection Resin is a system for welding cracks back together. This welding restores the original strength and loading originally designed into the concrete. Epoxy injection restores the structural qualities the concrete design intended. In other words under most conditions it makes the concrete as good as new. It creates an impervious seal to air, water, chemicals, debris, and other contamination.

A crack, obviously, is a sign of failure caused by stresses, inadequate design, improper curing, etc. One of the dangers of a structural crack is the effect that it has on the reinforcing bar. The reinforcing represents one of the main structural values of the concrete.

Cracks left unprepared allow moisture, road salts and other contaminants to penetrate and attack the rebar. The rebar deteriorates, losing the structuEpoxy Injection of concreteral value. Loosing the entire structure is often the result.

Epoxy injection resin has two purposes. First, it effectively seals the crack to prevent the damaging moisture entry. Secondly, it monolithically welds the structure together. Most people assume that this welding of the structure is the most important result of the repair. Actually what is most important is the sealing.

The sealing properties of the injection prevents premature deterioration of the reinforcing. This can be of equal, or in some cases greater importance than the structural welding. It would theoretically always be desirable to get this welding effect.

Crack Analysis

As with all repair and rehabilitation of concrete, the initial job analysis is by far the most important step. Epoxy Injection Resin will weld concrete cracks but, of course, will not repair the cause of the cracking.

Analyze each potential injection application to determine the exact cause or causes of the cracking. Correcting the cracking problem can be fairly simple, or may be difficult involving design changes.

Consult a structural engineer when design changes are necessary. Do this before starting the injection. Repairing cracks by Injection is effective after these design changes. Prevent future cracks by fixing the original cause of the cracking, when ever possible.

Parking garages are an example of cracking problem that require a structural engineering analysis. Often inadequate design for expansion/contraction is the cause for parking garage structural cracking. Avoid weld injecting a crack if there are not enough expansion joints. Sometimes flexible overlays such as Epoxy.com System # 485 can be used to overcome this defect. This does not however encapsulate the rebar in a way that will totally stop the premature deterioration of the steel. Often times additional joints are needed, thus the analysis of cracking problems is critical. more…


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