TECHNICAL
GUIDELINES
Prepared by the International Concrete Repair Institute December 1998
Guideline No. 03734
Copyright © 1998 International Concrete Repair Institute
Guide for Verifying Field
Performance of Epoxy Injection
of Concrete Cracks
TECHNICAL
GUIDELINES
Prepared by the International Concrete Repair Institute December 1998
Guide for Verifying Field
Performance of Epoxy
Injection of Concrete Cracks
Guideline No. 03734
Copyright © 1998 International Concrete Repair Institute
All rights reserved.
International Concrete Repair Institute
3166 S. River Road, Suite 132, Des Plaines, IL 60018
Phone: 847-827-0830 Fax: 847-827-0832
Web: www.icri.org
E-mail: info@icri.org
I N T E R N AT I O N A L
I N S T I T U T E
About ICRI Guidelines Producers of this Guideline
The International Concrete Repair Institute (ICRI) Task Group Members
was founded to improve the durability of concrete
Robert W. Gaul, Chair
repair and enhance its value for structure owners.
The identification, development, and promotion of the David L. Barton
most promising methods and materials is a primary Paul Derby
vehicle for accelerating advances in repair technology. David F. Dorsch
Working through a variety of forums, ICRI members Neal Kanaya
have the opportunity to address these issues and
Gerry Searles
to directly contribute to improving the practice of
concrete repair.
A principal component of this effort is to make
carefully selected information on important repair Contributors
subjects readily accessible to decision makers. During
the past several decades, much has been reported in Larry Hagan
the literature on concrete repair methods and materials Bill McCarty
as they have been developed and refined. Nevertheless, Larry Olson
it has been difficult to find critically reviewed infor Dennis Sack
mation on the state of the art condensed into easy to Jeff Small
use formats.
To that end, ICRI guidelines are prepared by
sanctioned task groups and approved by the ICRI
Technical Activities Committee. Each guideline is designed Acknowledgements
to address a specific area of practice recognized as
Peter Barlow
essential to the achievement of durable repairs. All
ICRI guideline documents are subject to continual Mike Beckman
review by the membership and may be revised as Peter H. Emmons
approved by the Technical Activities Committee. John Goss
Peter Harwood
Technical Activities Committee Morris Schupack
Robert W. Gaul, Chair Jim Suermann
Samson Bandimere John Trout
David L. Barton
Eric L. Edelson
Peter H. Emmons
Robert J. Gulyas
Peter Harwood
Kenneth M. Lozen
James E. McDonald
Jack A. Morrow
Dennis Pinelle
Randall W. Poston
03734- Guide for Verifying field performance of epoxy injection of concrete cracks
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Contents
1.0 Purpose and Scope.................................................................. 2
2.0 Quality Assurance/Quality Control Methods............................. 3
2.1 Visual Observation of Injection Process ............................ 3
2.2 Materials Testing............................................................... 4
2.2.1 Laboratory Tests....................................................... 4
2.2.2 Field Tests................................................................ 5
2.3 Removal and Evaluation of Cores from
Epoxy Adhesive Injected Concrete.................................... 6
2.4 NDT Methods for Quality Assurance
of Epoxy Adhesive Injection Repairs.................................. 7
2.4.1 Ultrasonic Pulse Velocity.......................................... 8
2.4.2 Impact Echo Test Method......................................... 8
2.4.3 Spectral Analysis of Surface Waves......................... 9
Cited References . ......................................................................... 9
This document is intended as a voluntary guideline for the
owner, design professional, and concrete repair contractor. It
is not intended to relieve the professional engineer or designer
of any responsibility for the specification of concrete repair
methods, materials, or practices. While we believe the infor
mation contained herein represents the proper means to achieve
quality results, the International Concrete Repair Institute must
disclaim any liability or responsibility to those who may choose
to rely on all or any part of this guideline.
Guide for Verifying field performance of epoxy injection of concrete cracks 03734-
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1.0 Purpose If there is any doubt that epoxy injection will
achieve the intended results, a pilot test program
and Scope should be conducted prior to letting the full
repair contract to determine whether the repair
The primary purpose of this document is to
objectives can be attained using the materials
provide the contractor, engineer, owner, and
and equipment proposed for the work. The
specifier with guidelines to assist in the devel
trial section can be used to evaluate bonding, to
opment of performance specifications for
confirm that adequate crack filling is possible,
epoxy adhesive injection work. Generally, the
and to obtain resin “standards” that are discussed
performance is measured according to whether
in the following section. The quality assurance
the epoxy adhesive has adequately filled the
program should also be evaluated during the
crack and has cured in place. In many instances
trial phase. If results of the trial work prove to be
a significant volume of repair work may take
inadequate and cannot be improved, other repair
place before the quality assurance testing can
methods need to be explored. Only the materials
be initiated. This document includes process-
and equipment proved to be successful in the
control methods which can help to assure that
pilot test should be used in conducting the work
satisfactory work is being performed. It is based
unless the contractor can demonstrate equally
on the assumption that the cause and extent of
satisfactory results with alternate materials
the cracking have been identified and that epoxy
or equipment.
adhesive injection has been carefully selected as
Although this guide is written for control
an appropriate repair technique. The injection
of epoxy injection of cracked concrete, the
contractor is able to control only the penetration,
quality assurance and quality control methods
proper proportioning, and mixing of the epoxy
described herein are also appropriate for
adhesive. Although it may be possible to remove
gravity-fed repairs of concrete cracks.
some contaminants, the contractor cannot control
the presence of contaminants within the crack
which may inhibit bonding. 2.0 Quality
Assurance/Quality
Control Methods
There are numerous methods available to evaluate
epoxy adhesive injection repairs. The quality
assurance program will be comprised of a number
of techniques, the amount and extent of testing
depending on the degree of assurance required.
Sections 2.1 and 2.2 discuss qualitative methods
of quality control which are usually conducted
by the contractor concurrent with the injection
work. Sections 2.3 and 2.4 deal with quality
assurance methods used to confirm performance
of the repair work.
2.1 Visual Observation of Injection Process
Useful information about the injection quality is
attained from a visual observation of the work. If
the crack is visible on both sides of the member,
then reasonable assurance that the crack is full
can be realized by observation of the material
exiting the ports along the crack when the
injection sequence described below is followed.
However, if only one side of the member is visible
it is more difficult to determine if adequate filling
Fig. 1: Injection showing port-to-port adhesive travel has been achieved. When injecting sequentially
03734- Guide for Verifying field performance of epoxy injection of concrete cracks
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through the ports along the crack, observing flow
from the adjacent port indicates that material is
moving along the crack but it does not necessarily
ensure that adequate filling has been achieved.
(Figure 1)
Liquid epoxy adhesive, like all liquids, flows
as a result of gravity and tends to seek the lowest
level in a void. Recognizing this tendency is a
great advantage in determining that full pene
tration has been achieved. Starting injection at
the lowest elevation in a crack and observing
the progression of adhesive from port to port
at successively higher elevation ports until the
highest elevation port is reached provides a measure
of assurance that the crack has been filled. If, after
the crack is first full and the adhesive has gelled,
the highest elevation port will not accept addi-
tional injection adhesive, it is usually reasonable
to assume that the adhesive has not drained out of
the crack that was once filled. The more viscous
liquid adhesives resist draining out of cracks.
Low viscosity liquid adhesives will stay in narrow
cracks because of capillary forces. However, it
is always wise to attempt to re-inject the highest
port before the adhesive has gelled. Fig. 2: ASTM D 695 compressive strength test.
2.2 Materials Testing
Quality assurance tests conducted either in the difficult to fabricate in the field. Also, the-test
field or the laboratory can determine with varying results are much more sensitive to minor flaws in
degrees of accuracy if the contractor has properly the test specimens.
proportioned and mixed the injection adhesive. Not every project justifies a laboratory test
because the time consumed and the expense of
2.2.1 Laboratory Tests the test may exceed the requirements of the project.
The only way to determine quantitatively if an Critical structural applications usually demand
epoxy adhesive is properly proportioned and definitive tests and the specifying authority must
mixed is to conduct a physical test under labor decide for each project whether quantitative tests
atory conditions. The two most common methods are justified. When required, strength tests are
to quantify physical properties are ASTM D 695 conducted at least once when a specific injection
Test Method for Compressive Properties of Rigid machine is first used on the job or during the
Plastics* (Figure 2) and ASTM D 638 Test pilot test program. The frequency of the subsequent
Method for Tensile Properties of Plastics. The testing should consider the history of the equipment
compression test is a convenient test because it and the contractor’s experience and track record.
utilizes specimens that are easy to make in the
field to detect discrepancies in the epoxy adhesive. 2.2.2 Field Tests
Samples of the epoxy adhesive are obtained either
from the discharge from the mixing head or from Testing the Mixed Adhesive
batched epoxy adhesive, and are prepared and Qualitative epoxy adhesive tests can also provide
tested in accordance with the applicable ASTM valuable information when having timely results
D 695. The tensile test is used less frequently is essential. Qualitative tests have an advantage
in the field because the tensile test specimens, over quantitative tests in that faster results are
which are cast between glass plates, are more obtained, reducing the amount of potentially
*Test Methods cited in this manner are from the American Society for Testing and Materials Annual
Book of ASTM Standards.
Guide for Verifying field performance of epoxy injection of concrete cracks 03734-
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defective epoxy adhesive injected. If, during that which will be used for all the sample testing
the work, the results indicate noncompliance, for the project. The color of the epoxy adhesive,
the work is stopped to identify and correct any the time to gel, and the ambient temperature (or
problems prior to continuing the work. Samples temperature of the adhesive if it is different from
are labeled to record the location and time when the ambient) are noted. The standard samples are
the epoxy adhesive was injected and are retained marked and retained for color comparison with
for the specifying authority. Qualitative tests other samples obtained during the work.
include a cure rate test and a visual review of the Injection adhesive tests should be conducted
prepared material. The gel time test described in at least once during the first 50 ft (15 m) of crack
ASTM C 881 Standard—Specification for Epoxy and thereafter for every 100 ft (30 m) of crack
Adhesive-Base Bonding Systems for Concrete— injected. Alternatively, if the work is proceeding
can be used to confirm that the injected resin will slowly then tests can be conducted on a time basis
harden. This test procedure may be modified to rather than a length basis. In this case a test every
accelerate the cure by elevating test temperatures. one to two hours may be appropriate.
This modification will substantially reduce the
Testing the Two-component
time required to obtain test results.
Injection Equipment
The important information here is whether It is extremely important that two-component
the material will cure, not necessarily how injection equipment be checked frequently to
long and at what temperature. This elevated be sure it is producing properly mixed material
temperature cure test will identify gross errors that is of the proper ratio. (Figure 4) The ratio
in proportioning or mixing, but it will not assure test is conducted by simultaneously collecting
that adhesive will cure to its expected physical each component and comparing the ratio of
properties at ambient temperature. the collected components to the desired ratio.
A clear container is used in the modified gel Measurement of the quantity of each component
time test in order to facilitate observation of the by weight is more accurate, but collecting the
material. (Figure 3) The sample is checked for specimens in transparent graduated containers is
improper mixing as evidenced by the presence an acceptable volumetric method. Specimens are
of streaks, and for improper proportioning as taken at the beginning of every shift, after any
evidenced by a difference in color between it repairs or adjustments are made to the equipment,
and the standard sample. Prior to initiating the and any time during a shift when other tests
work, a standard sample of each batch of adhesive indicate less than optimum results.
to used on the job should be established by The test is conducted under two conditions:
thoroughly hand mixing 3 oz. (85 g) in the correct 1) with each component flowing freely with no
ratio. The container should be clear and typical of external restrictions, and 2) with the flow of each
Fig. 3: Gel time test Fig. 4: Ratio test for
2 component equipment
03734- Guide for Verifying field performance of epoxy injection of concrete cracks
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Table 1—Field Test Methods and Acceptance Standards
Test Acceptability Standard
Ratio Measurement
Machine mixed epoxy adhesive 5% of nominal mix ratio unless otherwise
specified by manufacturer
Batch mixed epoxy adhesive as per manufacturer’s recommendation
Prepackaged tubes as per manufacturer’s recommendation
Pump Leakage Less than 5 psi (0.034 MPa) drop in 3 minutes
in either line when stalled at 80% or higher of
maximum possible discharge pressure
Cure Rate Measured quantity cures within +/- 10% of
standard that has been established for same
quantity prior to commencement of work
Visual No streaks
Color compares closely to standard
component externally restricted to simulate the
pressure conditions that exist when the adhesive
is being forced into a crack. The flow restriction
is achieved by disconnecting the mixing chamber
and attaching a valve to the end of each fluid line.
With pump operating, each valve is adjusted until
the pressure, as measured by a pressure gauge
in each line, is equal and is at least 80% of the
maximum possible operating pressure of the
machine. (Figure 5)
In addition to the ratio test, a “pressure test”
is advisable for two-component equipment. When
used to inject very narrow cracks, injection pumps
be can be “stalled” with no flow possible so that
they attempt to pump at high system pressures
for prolonged periods. These pressures can cause
internal “leakage” in the metering devices in the
pumps. To test for this leakage, close each discharge Fig. 5: Ratio and pressure test schematic
line at a point beyond the pressure gauges and
bring the pump system pressure in each discharge 2.3 Removal and Evaluation of Cores from
line to at least 80% of the maximum discharge Epoxy Adhesive Injected Concrete
pressure of which the pump is capable. Observe Epoxy adhesive injection quality can be assessed
the pressure in each line for three minutes. If the by the removal of core samples which include
pressure falls by more than 5 psi (0.034 MPa) in the repaired cracks. The samples are extracted
either line, there is internal leakage and the ratio by wet or dry core-drilling using a diamond-
of the two components may not be within the tipped bit. The contractor should detect rein-
required acceptance standard when the pump is forcement or prestressing steel at the designated
operating at high discharge pressures. core locations prior to coring. Scanning the
Guide for Verifying field performance of epoxy injection of concrete cracks 03734-
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concrete surface with a reinforcement locating viewed from the exposed length of the crack on
instrument can reduce the potential for cutting the sides of the core.
embedded reinforcement which could result A physical test is required to establish the
in reduction of structural integrity of the strength of the cured epoxy adhesive and bond
concrete member. strengths achieved on both sides of the crack.
The minimum core diameter required for Physical tests include several methods which
laboratory (physical) tests is dictated by the test stress the repair. A simple field test is to manually
method used. ASTM C 42 Obtaining and Testing apply a sharp blow with a hammer to the side of
of Drilled Cores and Sawed Beams of Concrete the core containing the repaired crack. Other
requires a minimum diameter twice the size of methods, which are conducted in a laboratory,
the large aggregate in the concrete, but recom- include ASTM C 39 Compression Test of
mends three times the size for both compressive Cylindrical Concrete Specimens and ASTM C
and splitting tensile tests. However, the core 496 Splitting Tensile Strength of Cylindrical
must have a diameter large enough to contain the Concrete Specimens. With the splitting tensile
crack to full depth if the core is to be used for a test, an attempt should be made to create tension
splitting tensile strength test. Smaller diameter perpendicular to the crack plane. (Figure 7) In
cores of 1 to 2 in. (25 to 50 mm) are adequate the splitting tension test, tensile stress at the
when a visual check is being conducted. The interface is produced by orienting the core on the
advantage of small diameter cores is that they testing machine platens so that the bond line is
are more readily filled and do less damage to the vertically aligned.
structure. When practical, the cores should be Fracture through the parent concrete away
drilled to the full depth of the repaired crack. from the repair indicates satisfactory perfor-
Usually one to two cores taken at random mance. The presence of shiny or glassy areas on
locations for every 100 ft (30 m) of injection is a face of hard cured epoxy adhesive exposed by
adequate. The specifying authority may increase the test fracture indicates that the glassy or shiny
or decrease the number and frequency of core area cured while exposed to air. From this it can
samples consistent with the nature of the work be concluded that the adhesive was in contact with
and the degree of quality assurance required. All only one face of the cracked concrete during cure
requirements for verification cores should be and there was no effective bond at that location
clearly defined in the project specifications. Cores because the crack was not full.
are usually examined to confirm penetration and Care must be taken to distinguish between
apparent set of the adhesive. (Figure 6) Most failure within the epoxy adhesive and bond
commonly, penetration is considered adequate failure between the concrete and epoxy adhesive.
if 90% of the crack is filled with adhesive, as If the crack is full of epoxy adhesive of the
Fig. 6: Cores showing epoxy penetration Fig. 7: Splitting tensile test
03734- Guide for Verifying field performance of epoxy injection of concrete cracks
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Electronically Generated Pulse by Impact
Piezoelectric Ceramic Source Transducer
Crack Crack
T Compression wave T
Reflecting surface
Concrete Receiver Concrete
Fig. 8: Ultrasonic Pulse Velocity (UPV)—Compression Fig. 9: Impact Echo (IE)—Compression wave reflected
wave blocked/delayed by crack by crack
proper ratio which has been well mixed, rejecting the techniques allow for a generalized assessment
repairs because of poor bond is inappropriate. inside of a structure which may otherwise appear
The ability to obtain bond may be beyond the to have integrity.
ability of the contractor unless proven otherwise It is generally recommended that all NDT
by a pilot test program completed in advance of methods be used on a “before and after” basis
starting the repair work. To compare the strengths for maximum effectiveness and that these
of the repaired specimen to sound concrete, investigations be accompanied by some limited
additional companion cores may be obtained for coring to verify test results at specific locations.
sound concrete adjacent to the repairs. Non destructivr testing methods are relatively
expensive for smaller projects. They require
2.4 NDT Methods for Quality Assurance of skilled technicians to conduct the tests and
Epoxy Adhesive Injection Repairs interpret results.
Nondestructive testing and evaluation (NDT&E)
with sonic and ultrasonic methods may be used 2.4.1 Ultrasonic Pulse Velocity
in some circumstances for testing epoxy adhesive The Ultrasonic Pulse Velocity (UPV) test involves
injection repairs. Presently there are three sonic sending a wave energy pulse through the concrete
NDT methods applicable to epoxy adhesive from a transmitter to a receiver. The pulse is
injection quality assurance: Ultrasonic Pulse generated by an electrical impulse, and the
Velocity (UPV), Impact Echo (IE), and Spectral instrument also records the time required for the
Analysis of Surface Waves (SASW). Of these pulse to travel from the source to the receiver.
methods, only UPV has an approved standard (Figure 8) The UPV test can be performed
(ASTM C597-83) governing the performance of from two opposite surfaces (direct test), two non-
the test. However, this ASTM test was approved opposite faces (semi-direct test), or the surface
for general flaw detection and does not specif of the concrete (indirect test) as illustrated in
ically address its use for injection quality Figure 8. Only the direct and semi-direct UPV
assurance purposes. Sonic NDT methods give tests are useful for a qualitative assessment of a
an indication of the relative degree of fill of repair, unless the repair at the surface of the
open cracks. They do not measure cure or concrete is of interest, since the indirect UPV
bond strength. test only penetrates the near-surface concrete.
Nondestructive testing methods are generally When testing is done before and after injection,
used for structures where large areas must be the UPV test provides a qualitative indication of
tested, or when other quality assurance techniques whether a crack is filled, partially filled, or
are inadequate. The major advantages of the NDT comparatively unfilled.
methods are that, unlike core sampling, no Recent research involving cross medium-
additional damage is done to the structure, and a medium (direct and angled tests above, below
close grid of data points can be tested. In addition, and across an injection zone) to analyze arrival
Guide for Verifying field performance of epoxy injection of concrete cracks 03734-
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of surface opening of cracks in concrete elements.
Signal Analyzer
IE cannot be used to assess whether an individual
crack is only partially filled. The IE method is
very effective up to depths of at least one meter.
Impact/Vibrator Receiver Receiver
Source R1 R2 2.4.3 Spectral Analysis of Surface Waves
A comparatively new NDT method known as the
Spectral Analysis of Surface Waves (SASW) has
been developed for use on concrete structures.
(Figure 10) This method is effective in measuring
T the overall effects of epoxy adhesive injection
repair on concrete, particularly when used as a
before and after test to compare the condition
of the member after the repair to its condition
Concrete Crack
before the repair.
The SASW method is based upon measuring
Fig. 10: Spectral Analysis of Surface Waves (SASW)— surface wave propagation in layered elastic
Crack blocks/delays signal media. Measurement of the surface wave velocity
with the SASW method allows calculation of
the estimated compression wave velocity of the
times can produce a velocity image. Such material at various depths between transducers
velocity tomograms show slow velocity zones mounted on the surface. The compression wave
of the cracking damage before injecting and velocity is related to Young’s Modulus, and there-
an improved, faster velocity tomogram after fore the relative condition of the concrete at
successful injection. various depths between the receivers can be
evaluated. Repeated tests at various locations can
2.4.2 Impact Echo Test Method give the condition versus location throughout the
In the Impact Echo (IE) test the surface is structure at various depths.
impacted by mechanical means with a small Like the IE method, the SASW method
impactor which produces stress waves as shown requires access to only one side of a structure.
in Figure 9. These stress waves propagate through The SASW test is only effective in measuring
and along the element being tested. Once the the overall average condition of the member,
traveling waves encounter a discontinuity, a based on stiffness and lateral wave propagation.
portion of the wave energy reflects back to the It cannot be used to determine the fill or strength
test surface. Unfilled or partially filled cracks of a particular crack unless there is only one crack
would be an example of such a discontinuity. between the pair of receivers. If closely spaced
The reflected stress wave energy, or “echo,” is 0.15 m (0.50 ft.) SASW tests are conducted,
monitored by a receiver placed on the concrete one can obtain a simple tonogram, or image,
surface. Since both the source and the receiver of the variation of velocity vs. wave length into
are placed on the concrete surface, only one the concrete.
surface, unlike the UPV method, needs to be
accessible for testing of a concrete element. Like Cited References
UPV, impact echo used in this manner can only ASTM (Annual)
be used “qualitatively” to assess the effectiveness Annual Book of ASTM Standards
of epoxy adhesive injection. American Society for Testing and Materials
The IE method, using a systems of two trans- 100 Barr Harbor Drive
ducers, can be effective in determining the depths West Conshohocken, PA 19428-2959.
03734-10 Guide for Verifying field performance of epoxy injection of concrete cracks
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1323 Shepard Drive, Suite D
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Phone 703-450-0116
Fax 703-450-0119
E-mail: mcollins@icri.org
Web: www.icri.org
