Discuss about the Crack Injection Method.
Concrete is a durable part, which deteriorates with time due to different factors. Some of the major results, which may lead to the deteriorations of concrete structure, include the physical damage, chemical attack, structural movement or even material degradation due to the exposure of the materials to severe and unworthy environments (Kennedy 2008). The presence of these conditions leads to the need of the crack injection methods in order to rehabilitate the concrete structures. The concrete structures are expensive and a lot of time is invested in their construction. This leads to the call for their rehabilitation to help give the structure their value of money. In addition, the rehabilitation helps to extend their life and help the structure to serve their intended purpose the mentioned duration (Panasyuk, Marukha & Sylovanyuk 2014). Suitable methods for rehabilitating these structures are needed and the crack injection method is one of the key methods, which help to provide the service and life for the structures. Moreover, all concrete structures are vulnerable to deterioration and damage. Failure to rehabilitate the concrete structure, more failures is experienced and this may lead to the shortening of the life of the structures. In addition, time factor is the rehabilitation for the projects is crucial on which method need to be used for the rehabilitation.
Crack injection methods have grown to be one of the most crucial alternative to the total; replacements of the concrete structures. Today, Epoxy Injection Resin is most an applied method to crack injection on concrete structures. In order to achieve the best results, the crack inject has to follow a certain process. The Epoxy Injection Resin is a method whereby cracks are welded together and therefore enhance the stability of the concrete structures. This methods helps in cost saving and helps to protect the raber and water leakages (Calder 1986). The standard procedure of carrying out the crack injection will be the main content of this report. In addition, the paper will look at the key notes of the crack injection method as a method of renovating structures.
The crack injection process is one of the effective repair methods of the concrete structures. On the injection methods, the location of the cracks is key on the determination of the approach used for the injection. For the method to be applied and be effective, the cracked surface and the size of the crack are the main factors, which must be considered (Fonseca & Glenn 2003). The crack injection method is known to be able to restore the structural integrity of different structures and reduction of the moisture penetration. Moreover, before the application of any crack injection method, the main cause of the fracks must be assessed, corrected and the objective of the repair be determined. There are different crack injection methods, which are used to rehabilitate the concrete structures. Epoxy Injection Resin and Polyurethane Foams are two main methods that are commonly used to repair the cracks in concrete (Sandia National Laboratories & United States 2009). There are different situations, which call upon on the use of some of the methods while denying the use of other. Cost factors, use of additional other materials, expansion of the materials used are among the main reasons for the adoption of the crack injection methods. All these factors of the cracks are able to determine the type of crack injection method to be used in any particular case. In addition, the final requirement of the status of the crack also determines the method to be chosen . For instance, the need for the increase of the strength of the concrete structure calls for the use of Epoxy Injection Resin. This method helps to produce a stronger final structure due to the available structure.
The first and initial stage and procedure for the repair of any concrete structure is the crack analysis. At this stage, the characteristics of the different cracks are determined and their status and their cause. The analysis helps to determine the type of method to be used at any particular element of the structure. The crack analysis also involves the analysis of the structure and the final requirement of the projects. In addition, the strength factor of the structures which have the structural failure will be a key factor to determine the method used. In addition, this step of crack analysis will enhance any structural designing, which the structural engineer will take. This step will help to the engineer on the measurement of then crack and help him or her on the decision which method will be suitably favor the crack site according to the end result requirement. More importantly, the step will help to put in a nutshell the rabar and help to reduce the premature deterioration of the steel used (Hajialiakbari Fini 2008). The joints which will help to increase the stability factor of the structure will be needed at they can be decided through the crack analysis process. Therefore, the crack analysis process becomes a crucial method to be involved in the crack injection method.
The next main stage of the site injection method is the injection preparation and surface preparation. The main difference between the different methods of crack inject methods is the type of injection involved. This is a step where the structural preparation of the cracks is already known and the materials to be used are determined. On the injection preparation, the cleaning of the cracks is one of the major steps, which need to be undertaken (Allen, Edwards & Shaw 1993). The injection method means that the old concrete structure will need to bond with the help of the injection materials. Dirt at the cracks is likely to reduce the strength of the bonding material by a significant factor. Cleaning of the cracks helps to remove any available contaminations at the crack site to enhance the strength of the bonding. Some of the major materials, which might be present as contaminants, include oil, grease, dirt, and even fine particles of concrete (Felker & Parcells 2009). The effectiveness of the repairs and the bonding is determined by the cleanliness of the cracks. The cleaning of the cracks is done through vacuuming or flashing with water at high pressure. This will ensure that these contaminants are successfully removed and thus enhance the bonding factor of the materials used and the concrete structure.
another key step is the drilling of the surface ports. This procedure lies in the injection preparation and enhances the bonding factor of the concrete structure repair (United States 1988). The ports are key to be drilled with vacuumed attached swivel drill chuck and by the use of hollow drill bits. This will help to clean the site and remove any concrete dust on the ports, which can be much dangerous on the ability of the injection to bond the cracks and therefore reducing the injection strength. The drilled ports must not include any concrete dust, and that is the main use of the vacuum in the drilling process. The main reason is that the concrete dust might be much detrimental to the bonding process and able to reduce the effectiveness of the injection process by several ways, such as the reduction of the viscosity of the injection materials or even formation of semi-paste material, which might block the ports (Sandia National Laboratories & United States 2009). The drilling procedure, on the other hand, must be followed ad ports of required sized be dilled. More importantly, the spacing of the ports must be determined well to enhance the tightening of the crack. A qualified applicator must be used for this process since it is key to the success of the crack repair of the structure. Another important area is that the depth of the ports must be determine well. The spacing of the cracks must rage between four and eight inches in order to achieve the best tightening of the cracks.
The next key step is the procedure is the setting out of the surface ports. The ports must be aligned directly over the cracks in order to allow free flow of the injection material this will ensure that the injection material will reach the required place and enhance the bonding factor. To reach this, one can place a nail at the top of the surface of the port and then gently tap the nail to the crack (Sasse 1986). This will temporarily hold the port in place and ensure that the flow of the injection material will be achieved.
The next step is the sealing of the cracks. The filling must be done in order to prevent the injection material from leaking even before it has gelled out. Epoxy, polyester or even other suitable material can be used as a seal material to the surface of the crack and then allowing it to harden. In addition, cementitious seals can also be used on these surfaces (Oak Ridge National Laboratory & United States 2011). The cementitious seals are mostly used where the appearance of the completed works is important needed. In addition, is a permanent glossy look along the crack is questionable or even high pressure is not need, a strippable plastic seal which is removable can be applied and then stripped out after the hardening of the seal.
The next step in the procedure involves injection of the resin and this is best achieved with the use of an injection machine. On the injection, low-pressure or high pressure can be used according to the different conditions of the ports and the cracks. Nevertheless, the flow of the resin must at the end reach the destination on the ports and enhance the bonding at that point. The cracks may be in different direction and it has to be noted that for the vertical cracks, the injection must start from the lowest port and continue all the way to the cracked parts of the concrete structure. When the injection material oozes out, it is a sign that the crack has been filled up. The filled port must be plugged and the filling process continues to the next ports available until the entire ports are filled and plugged (Hassoun 2000). The process has to continue until the entire cracked areas are filled with the injection material. More importantly, during the filling process, the compression spring on the dispensing machine must be pushed slowly and with constant pressure. Since the repair of the cracked concrete structure is meant to save on cost, this will reduce the possibilities of leaks and blowouts and therefore help to reduce wasting of the injection material. In addition, the constant pressure and gentle use will enhance the full penetration of the injection material and therefore able to force the material to reach the target point.
The last, critical step in the procedure is the removal of the ports. The removal of the ports must be undertaken between 24 to 48 hours at room temperature after the time of injection of the material. This time allows the injection material to cure and penetrate to the cracks and therefore enhancing the bonding. The removal process of the ports may be through striking the ports with a hammer or trowel. As noted earlier, if the appearance of the area is a great issue, the removal of the seal must be undertaken (Sasse 1986). This depends on the sealing material used since the material, which can be chipped, can be used as a seal and then removed after the removal of the ports. The peeling off the seal must be undertaken after the repair has be cured fully in order to avoid any destruction and creation of lines of weaknesses.
In conclusion, the crack injection method is a simple process that is able to attain high level of standards of the concrete structures. The injection process starts with the surface preparation, which includes cleaning of the surface and then moves to the drilling of ports. The ports enhance the injection material to reach the cracked locations and enhance the bonding. Port surface setting and sealing of the cracks are the next key steps of this procedure. The next step involves the injection of resin or the injection material and allowing it to bond and dry up and then the ports are removed.
Allen, R. T. L., Edwards, S. C., & Shaw, J. D. N. (1993). The Repair of concrete structures. London, Blackie Academic & Professional. https://site.ebrary.com/id/10165482
Calder, A. J. J. (1986). Repair of cracked reinforced concrete: assessment of injection methods. Crowthorne, Berkshire, Bridges Division, Highways and Structures Dept., Transport and Road Research Laboratory.
Felker, V., & Parcells, W. H. (2009). The effects of the fly-ash slurry injection method to eliminate depressed transverse cracks. Topeka, Kan, Kansas Dept. of Transportation.
Fonseca, F., & Glenn, B. W. (2003). Flexural performance of retrofitted reinforced concrete cantilevered bent caps. Part 2 Part 2. Salt Lake City, Utah, Utah Dept. of Transportation.
Hajialiakbari Fini, E. (2008). Adhesion mechanisms of bituminous crack sealant to aggregate and laboratory test development. Dissertation Abstracts International. 69-05
Hassoun, A. A. M. (2000). Effectiveness of the epoxy injection repair method for cracked reinforced concrete walls.
Kennedy, L. (2008). Concrete repair manual. Farmington Hills, Mich, ACI International.
Oak Ridge National Laboratory, & United States. (2011). Materials for High-Pressure Fuel Injection Systems. Oak Ridge, Tenn, Oak Ridge National Laboratory. https://www.osti.gov/servlets/purl/1027862/.
Panasyuk, V., Marukha, V., & Sylovanyuk, V. (2014). Injection Technologies for the Repair of Damaged Concrete Structures. https://proxy.cegepat.qc.ca/login?url=https://dx.doi.org/10.1007/978-94-007-7908-2.
Sandia National Laboratories, & United States. (2002). Leak Testing and Implications of Operations to Locate Leak Horizons at West Hackberry Well 108. Washington, D.C, United States. Dept. of Energy. https://www.osti.gov/servlets/purl/800989-mNzV3L/native/.
Sasse, H. R. (1986). Adhesion between polymers and concrete / Adhe?sion entre polyme?res et be?ton: Bonding · Protection · Repair / Reve?tement · Protection · Re?paration. https://dx.doi.org/10.1007/978-1-4899-3454-3.
United States. (1988). High molecular weight methacrylate (HMWM) concrete crack bonder: information package. Washington, D.C., Federal Highway Administration.