Magazine of concrete research, volume 59, issue 10, 1 dec 2007 771776. Destructive testing methods include exploratory openings, corings, and pullout testing. This statement is based on the correlation values with the compression. To ensure that the surface preparation procedures were followed as per the specifications, the pull off strength of the prepared surface prior to repair application is measured. The second one is slant shear test, which has the shear failure mode and it can be done only in the lab. Bond characterization between concrete substrate and. Pullout tests on hardened concrete the constructor. Robins and austin presented the idea of a bond failure envelope for concrete repairs. Which one of the followings is the objective of this study and course. Experiments were carried out to study the effect of workmanship and environmental conditions on bond strength for concrete patch repairs. Tensile bond tests are increasing in popularity as a means of measuring this adhesive property, both on site for quality control and in the laboratory for materials evaluation.
Request pdf pulloff adhesion testing for concrete repairs where one material is bonded to another, the only appropriate test method to measure bond or adhesion is often a peel or pulloff. The pulloff test method is one of the tensile test methods commonly used to assess the adhesion between the repair overlay and the existing concrete substrate. Proceedings of the institution of civil engineers structures and buildings. Astmd7522 standard test method for pulloff strength. Pdf evaluation of test methods for measuring adhesion. It is an exceptionally good tool for assessing the progressive deterioration in these cases when exposed to normal or aggressive environments. Four repair materials, sandcement mortar, acrylic modified cementitious mortar, sbr modified cementitious mortar, and flowing concrete, were tested with mainly three test methods core pull off test, patch compressive test, and patch flexural test. Existing concrete overlay fracture surface, a f adhesive steeldisk tensile pull off force, f t figure 1. Limpet pulloff test for measuring in situ compressive strength of concrete and bond strength of concrete patch repairs by ae long, dj cleland, pam basheer and y bai year. These methods are used in completing the field condition survey of buildings. The center to center distance of adjacent pulloff tests within a patch shall be at least 6 inches. Astm c1583 c1583m standard test method for tensile. The compressive strength can be considered as proportional to the ultimate pullout force.
The evaluation of tests for repair materials used on. It was found later also particularly suited for assessment of bond strength of repairs. The pull off test method is one of the tensile test methods commonly used to assess the adhesion between the repair overlay and the existing concrete substrate. Pulloff adhesion testing for concrete repairs request pdf. The test for drummy areas shall be conducted using a small hammer along the whole surface area of the concrete patch repairs and delaminated areas shall be characterised by a drummy or hollow sound. The quality of concrete repairs is determined by the adhesive strength between the repair material and the substrate. This paper discusses the main issues relevant to tensile bond testing, namely material properties, surface. It is superior to rebound hammer and windsor probe test because of. Tensile bond strength of a high performance concrete bridge. Evaluate bond strength of coatings and cementitious material with pullof testing. Tensile bond tests are increasing in popularity as a means of measuring this. The importance of bond strength in concrete repair projects. Limpet measures the pull off strength of the surface zone of concrete and the bond strength of patch repairs with minimal damage.
Schematic of pulloff test principle the pulloff strength s po is defined as the tensile pulloff force f t divided by the area of the fracture surface a f. C 1583 tensile strength of concrete surfaces and the bond strength or tensile strength of concrete repair and overlay materials by direct tension pulloff method 3. It is an exceptionally good tool for assessing the progressive. Portland cement concrete repairs with dry and saturated surface dry conditions, and three rapid repair cementitious materials were used for comparative purposes to investigate the benefits over other. Concrete pulloff testing is used to confirm the substrate strength prior to the installation of repair materials or as quality assurance for the installation of overlays or fiber wrap. Concrete adhesion pulloff test the pulloff adhesion test determines the maximum perpendicular force that a surface area can bear before a temporarily stuck plug of material is detached. Evaluation of bond strength between overlay and substrate in. Cutting an opening in the area of a previous repair reveals information about the preparation, application, and. The tensile pulloff adhesion test of the existing concrete should be conducted as part of the condition evaluation report. Pull off adhesion testers for concrete strength testing proceq. According to the astm d4541 standard, the general pull off test is performed by fixing, with an adhesive, a loading fixture disk to the surface of the coating. Such testing follows astm c 1583, standard test method for tensile strength of concrete surfaces and the bond strength or tensile strength of concrete repair and overlay materials by direct tension pulloff method.
Tensile bond strength of a high performance concrete. Astm d7522d7522m 09 standard test method for pulloff strength for frp bonded to concrete substrate. This test method is not appropriate for determining. Pull off adhesion testers for concrete strength testing. B15 cementitious patch repair of concrete department of state growth prior to commencement of any patch repair of concrete, the contractor shall assess the affected concrete structure or component to determine the influence of spalled, deteriorated. Bond strength and pulloff testing refer to a test method outlined in astm c1583 and d4541.
The purpose of the test is to measure the maximum tensile strength of the repair material on concrete. Field testing of concrete structures include nondestructive testing and destructive testing. Tensile bond testing of concrete repairs springerlink. Although the sand patch test 14,25 and the profilometric method 44,65 are still popular for evaluating the surface morphology of concrete, tayeh et al. The results obtained with the pull off test showed that it is fully feasible to be employed to estimate the strength of concrete in situ. The force required to extract the disc is measured and correlated with compressive strength of concrete. After core drilling, a steel plate is glued to the.
Figure 10 pulloff test method for concrete patch repairs cleland and long 1997. The pulloff partially destructive test for concrete. Pull off test to evaluate the compressive strength of. Laboratory samples were made by placing repair concrete 0, 2, 5, 10, and 30 minutes. To ensure that the surface preparation procedures were followed as. The simplicity and accuracy of the test has made it the most popular test method in projects. Astm d7234 19 standard test method for pulloff adhesion. The laminator should receive relevant training to possess appropriate competence in the lamination. Astmd7522 standard test method for pulloff strength for. Nov 11, 2019 the tensile pull off adhesion test of the existing concrete should be conducted as part of the condition evaluation report. The lok test system is used to obtain a reliable estimate of the inplace strength of concrete in newly cast structures in accordance with the pullout test method described in astm c900, bs 1881. Standard test method for evaluating the adhesion pulloff. Initially, the pull off test was developed primarily aiming at unplanned insitu strength determination. In 1974, the concept of using pulloff test as a means of predicting the compressive strength of concrete was patented in the uk by professor long at queens university belfast.
Thus, the quality of the bonded patch repair is directly dependent on the skill. The weakest path could be along an interface between two layers or a cohesive facture within one layer or a combination of these. Spall repair of concrete repair horizontal application. Although the sand patch test 14,25 and the profilometric method 44,65 are still. Note this test method is a destructive test and spot repairs are required. Evaluation of bond strength between overlay and substrate. This test method is not appropriate for determining the pulloff strength of the frp from the patch material. This statement is based on the correlation values with the compression strength test, both in cylindrical and prismatic specimens, compared to the values of pull off test both with r 2 above 0. The pulloff test for concrete patch repairs, proceedings of the institution of civil engineers, structures and buildings,1997,122,451460 talbot c. Limpet is equally suitable for on site and laboratory use. An evaluation of equipment and procedures for tensile. The test sample is subjected to increasing tensile stress until failure occurs.
Experimental research on concrete strength prediction by. Concrete pulloff testing is used to measure the direct tensile strength of. An additional test method is required to determine the pulloff strength of the patch from the. Portland cement concrete repairs with dry and saturated surface dry conditions, and three rapid repair cementitious materials were used for comparative purposes to investigate the benefits over other alternatives for using bonding agents. Astm c1583 c1583m, standard test method for tensile strength of concrete surfaces and the bond strength or tensile strength of concrete repair and overlay materials by direct tension pulloff.
Pulloff test as a means of predicting the compressive strength of concrete was originally developed at queens university belfast by professor a. This test method serves as a means for uniformly preparing and testing coated surfaces, and evaluating and reporting the results. Repair to concrete structures often involves breaking out cracked concrete and replacing this and areas of spalling with a mortar or concrete. Bond characterization between concrete base and repairing sfrc. Average of pulloff strengths of experimental repairs. This test requires core drilling through the repair into the substrate approximately 12 in. Various factors influencing interlayer bond strength at the interface of the concrete repairs. Corrosionpedia is surface preparation for concrete repairs. A modified bond wrench test for evaluating bond strength of.
Good adhesion of a repair material to concrete is of vital importance in the application and performance of concrete repairs. Shear bond testing of concrete repairs sciencedirect. Schematic of pulloff test principle the pulloff strength s po is defined as the. This was based on core pull off, slantshear, and patch tests, which give pure tension and compressionshear stress states. The distance from the center of a pulloff test and the edge of the. The pulloff method involves bonding a circular steel probe to the surface of the concrete. Figure 10 pull off test method for concrete patch repairs cleland and long 1997. This test has now been accepted in british standards, bs 1881207. The equipment used for this test, called lim pe t figure 11a, is well established in the uk and has a 10 kn. This test method is not appropriate for determining the pull off strength of the frp from the patch material.
The test determines the greatest perpendicular force in tension that a surface area can. Limpet measures the pulloff strength of the surface zone of concrete and the bond strength of patch repairs with minimal damage. It was not until the 1970s howe ve r, following work by richards and ma l h o t r a, that this approach to testing began to be re. The development and maintenance of a sound band is an essential requirement of a concrete patch repair. The pull off test for concrete patch repairs, proceedings of the institution of civil engineers, structures and buildings,1997,122,451460 talbot c.
Astm d7522d7522m09 standard test method for pulloff. The test bolt including disc and stem is mounted on the inside of the form prior to placing concre t e. Limpet pulloff test for measuring in situ compressive. This type of testing is used to evaluate and provide a qualitative value of coatings applied to a concrete or other substrate surface. Pulloff testing is the most widely used test method to assess bond strength. Destructive and nondestructive field testing of concrete.
Delaminated patch repairs shall be removed and repaired in accordance with the requirements of this section. The evaluation of tests for repair materials used on concrete. Limpet pull off test for measuring in situ compressive strength of concrete and bond strength of concrete patch repairs by ae long, dj cleland, pam basheer and y bai year. Pulloff adhesion testing for concrete repairs authors. Four repair materials, sandcement mortar, acrylic modified. A modified bond wrench test for evaluating bond strength. Adhesion of the new patch to the original concrete is generally considered to be an important criterion in judging the success of the repair. The laminator should receive relevant training to possess appropriate competence in the lamination process. Repair, evaluation, maintenance, and rehabilitation research program. This type of testing is used to evaluate and provide a qualitative value of coatings applied to a concrete or other. The pull off partially destructive test for concrete. Request pdf pulloff adhesion testing for concrete repairs where one. Destructive testing methods include exploratory openings, corings, and pull out testing. The test for drummy areas shall be conducted using a small 0.
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