Specification:Repairing cracks in concrete by injecting epoxy resin

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=GENERAL=

SUMMARY
 This procedure includes guidance on patching cracks in concrete by injecting an epoxy adhesive. Epoxy Injection should be used for DORMANT CRACKS - cracks that remain unchanged. Dormant cracks generally pose little danger. However, if left unrepaired, they will provide channels for moisture penetration. The calculated maximum crack width for concrete should not exceed 0.3 mm. Consult a professional to determine the cause for cracking and its source, as superficial repairs can aggravate the problem. See Specification:General project guidelines for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:  Safety Precautions Historic Structures Precautions Submittals Quality Assurance</li> Delivery, Storage and Handling</li> Project/Site Conditions</li> Sequencing and Scheduling</li> General Protection (Surface and Surrounding)</li> </ol> </li> These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the State Historic Preservation Officer (SHPO). For guidance in monitoring cracks, see 04200-02-S.</li> </ol>

MANUFACTURERS
<ol type="A"> Abatron, Inc. 5501 95th Ave. Kenosha, WI 53144 800/445-1754 or 414/653-2000</li> Sika Corporation 201 Polito Ave. Lyndhurst, NJ 07071 201/933-8800</li> </ol>

MATERIALS
<ol type="A"> Epoxy Resin (Abatron, Inc., Sika Corp.), or approved equal. <ol> For Fine Cracks: Epoxy shall be a two-part type, low viscosity epoxy adhesive material containing 100% solids and shall meet or exceed the following characteristics when tested in accordance with the standards specified.</li> Characteristics of Components: <ol> Component A - shall be a blend of modified epoxy resins.</li> Component B - shall be a blend of modified amine curing agents. </li> </ol> </li> Test Method Requirements: <ol> Component A - Brookfield RVT, 700 maximum; Viscosity @ 77 +/- 3 degrees F., cps; Spindle No. 2 @ 20 rpm.</li> Component B - Brookfield RVT, 240 maximum; Viscosity @ 77 +/- 3 degrees F, cps; Spindle No. 2. </li> </ol> </li> <li>Properties of Combined Components: When mixed in the ratio of two parts Component A to one part Component B by volume; or 100 parts Component A to 44 parts Component B by weight, shall be:</li> <ol> <li>Potlife, 60g @ 77 +/- 3 degrees F., minutes; 25 minutes maximum.</li> </ol> </li> <li>Properties of the Cured Adhesive: When cured for seven days @ 77 +/- 3 degrees F., unless otherwise specified, shall be: <ol> <li>  Ultimate Tensile Strength:  ASTM D638; 8000 minimum.</li> <li> Compressive Yield Strength, psi: ASTM D695*; 15,000 minimum.</li> <li> Heat Deflection Temperature: ASTM D648*; 130 F. minimum. </li> </ol> </li></ol></li><li>For Wide Cracks: <li>Epoxy shall be a two-part gel epoxy adhesive material containing 100% solids and shall meet or exceed the following characteristics when tested in accordance with the standards specified.</li> <li>Properties of Combined Components: When mixed in the ratio of two parts Component A to one part Component B by volume; or 100 parts Component A to 34 parts Component B by weight shall be: <ol> <li>  Potlife, 200g @ 77 degrees F. +/- 3 degrees F., minutes.</li> </ol> </li> <li>Properties of the Cured Adhesive: When cured for seven days @ 77 degrees F. +/- 3 degrees F., unless otherwise specified, shall be: <ol> <li> Ultimate Tensile Strength: ASTM D638; 1,500 psi minimum. </li> <li> Compressive Yield Strength: ASTM D695; 6,000 psi minimum. </li> <li> Heat Deflection Temperature: ASTM D648; 105 F. minimum. </li> </ol> </li> </ol> </li></ol></li> <li>Surface Seal: (Epoxy Mortar or Oil-free Clay) <ol> <li>Description: The surface seal material is that material used to confine the injection adhesive in the joints or cracks during injection and cure.</li> <li>Properties: The surface seal material shall have adequate strength to hold injection fittings firmly in place and to resist injection pressures adequately to prevent leakage during injection. The material shall not leave a residue upon removal.</li> </ol> </li> </ol>

EQUIPMENT
<ol type="A"> <li>Equipment for Injection: <ol> <li>Type: The equipment used to meter and mix the two injection adhesive components and inject the mixed adhesive into the crack shall be portable, positive displacement type pumps with interlock to provide positive ratio control of exact proportions of the two components at the nozzle. The pumps shall be electric or air powered and shall provide in-line metering and mixing.</li> <li>Discharge Pressure: The injection equipment shall have automatic pressure control capable of discharging the mixed adhesive at any pre-set pressure up to 200 psi + 5 psi and shall be equipped with a manual pressure control override. For injection of the gel epoxy, the equipment shall be equipped with the above features and be able to pump at up to 5,000 psi.</li> <li>Ratio Tolerance: The equipment shall have the capability of maintaining the volume ratio for the injection adhesive prescribed by the manufacturer of the adhesive within a tolerance of + 5% by volume at any discharge pressure up to 200 psi. For gel epoxies, the ratio will be checked by weight at up to 5,000 psi.</li> <li>Automatic Shut-Off Control: The injection equipment shall be equipped with sensors on both the Component A and B reservoirs that will automatically stop the machine when only one component is being pumped to the mixing head.</li> <li>The manufacturer of the injection equipment and the manufacturer of the epoxy resin adhesive for injection shall be one and the same.</li> </ol> </li> </ol> =EXECUTION=

EXAMINATION
<ol type="A"> <li>Examine the nature and severity of the crack: <ol> <li>What direction are the cracks going and where are they the widest?</li> <li>Note sloped floors, bulging walls and doors that do not fit.</li> </ol> </li> <li>Determine the probable cause: <ol> <li>Foundation erosion</li> <li>Decay of materials</li> <li>Structural failure</li> <li>Change in materials or geometry</li> <li>Thermal and moisture changes</li> </ol> </li> <li>Determine possible consequences if left unrepaired.</li> <li>Evaluate alternative methods of repair.</li> <li>For cracks associated with thermal movement look for: <ol> <li>Horizontal or diagonal cracks near the ground at piers in long walls: due to horizontal shearing stresses between the upper wall and the wall where it enters the ground.</li> <li>Vertical cracks near the ends of walls</li> <li>Vertical cracks near the top and ends of the facade</li> <li>Cracks around stone sills or lintels: due to expansion of the masonry against both ends of the tight fitting stone piece that cannot be compressed.</li> </ol> </li> </ol>

PREPARATION
<ol type="A"> <li>Surface Preparation: <ol> <li>Substrate Conditions: Do not proceed with installation of joint sealers until contaminants capable of interfering with their adhesion are removed from joint substrates.</li> <li>Surfaces adjacent to joints or other areas of application shall be cleaned of dirt, dust, grease, oil or other foreign matter detrimental to bond of epoxy injection surface seal system.</li> <li>Entry ports shall be provided along the crack at intervals of not less than the thickness of the concrete member at that location.</li> <li>Surface seal material shall be applied to the face of the crack or end. For through cracks, surface seal shall be applied to both faces.</li> <li>Enough time for the surface seal material to gain adequate strength shall pass before proceeding with the injection.</li> </ol> </li> </ol>

ERECTION, INSTALLATION, APPLICATION
<ol type="A"> <li>If, before repairs are made, the crack is still damp, be sure to use an epoxy appropriate for damp conditions.</li> <li>Seal both sides of cracks with an epoxy mortar or oil-free clay, leaving small holes through which epoxy resin will be injected. 1/8" to 1/4" diameter tubing can be used to form holes. Holes should be 2"-4" long, roughly 8" apart.</li>   <li>Inject 2-component epoxy using device as provided by manufacturer.</li>    <li>Injection of epoxy adhesive shall begin at lower entry port and continue until there is an appearance of epoxy adhesive at the next entry port adjacent to the entry port being pumped.</li>    <li>When epoxy adhesive travel is indicated by appearance at the next adjacent port, injection shall be discontinued on the entry port being pumped, and epoxy injection shall be transferred to next adjacent port where epoxy adhesive has appeared.</li>    <li>Perform epoxy adhesive injection continuously until cracks are completely filled.</li>    <li>If port to port travel of epoxy adhesive is not indicated, the work shall immediately be stopped and the engineer notified.</li>    <li>When cracks or joints are completely filled, epoxy adhesive shall be cured for sufficient time to allow removal of injection or port sealing devices.</li> <li>The outermost quarter inch of the crack shall be filled with a colored epoxy material of the installers choice subject to prior approval of the SHPO. The colored epoxy filler shall match the existing material which it is filling and shall not be discernible from a distance of 15 feet.</li> </ol>

ADJUSTING/CLEANING
<ol type="A"> <li>Upon completion of work, remove all seal material and other residue from site. Remove and clean exposed surfaces of residue or staining resulting from this work.</li> </ol>