The purpose of the service-condition tests is to determine the basic data required to predict the performance of the anchor under service conditions.
R8.1 Service-condition tests establish the general strength data for the anchor system in uncracked and cracked concrete and under various temperature and environmental exposure conditions, as well as in conjunction with seismic loading.
8.2—Required tests
Required service-condition tests are given in Table 3.1 for adhesive anchors qualified for use in uncracked concrete only and in Table 3.2 or 3.3 for adhesive anchors qualified for use in both uncracked and cracked concrete. Test require- ments for adhesive anchors assessed to resist seismic loads are defined in Table 3.2.
R8.2 Anchors to be qualified for use in cracked concrete are installed in hairline cracks, which are then opened to a crack width w of 0.3 mm before anchor loading. This crack width is consistent with the expected response of rein- forced concrete structures under sustained load.
8.3—Conduct of tests
R8.3 Service-condition tests are to be performed on anchors installed in accordance with the MPII.
8.3.1 Prepare test members, install anchors, and test in accordance with Chapter 4 unless otherwise noted.
8.3.2 Perform tests in dry concrete.
8.3.3 Perform tests with air, concrete, and anchor at standard temperature unless otherwise noted.
8.4—Tension tests in uncracked and cracked concrete
Refer to Table 3.1, Tests 7a and 7b; Table 3.2, Tests 11a, 11b, 11c, and 11d; and Table 3.3, Tests 8a and 8b.
R8.4 Tests are conducted in low- and high-strength concrete to establish the characteristic limiting bond stress. Fig. 7.3—Procedure to verify effectiveness of adhesive
injection method.
Fig. 7.4—Torque test setup. Fig. 7.2—Required labeling for products not tested for
Depending on the characteristics of the adhesive and the embedment depths for which the system is to be assessed, it may be necessary to take special measures to achieve bond failures in these tests (refer to 4.7). The use of confined tests is permitted under certain conditions and can enable the use of reference tests for establishing characteristic limiting bond stress values.
8.4.1 Purpose—These tests are used to establish the bond resistance of the anchor system.
8.4.2 Conduct of tests—Perform unconfined service- condition tension tests in accordance with Section 4.7 in both low- and high-strength concrete.
8.4.2.1 It shall be permitted to perform the service- condition tension tests described in Table 3.1, Tests 7a and 7b; Table 3.2, Tests 11a through 11d; and Table 3.3, Tests 8a and 8b as confined tests if the evaluation for τk,cr is
performed in accordance with 10.4.5.3.3.
8.5—Tension tests at elevated temperature
Refer to Table 3.1, Test 8a; Table 3.2, Test 12a; and Table 3.3, Test 9a.
R8.5 Tension tests establish the anchor performance at concrete temperatures elevated above standard temperature for long and short durations (2.2—elevated concrete temperature). Temperature Category A provides a standard approach that assumes a potential long-term elevated temperature consistent with hot climate exposures and a short-term temperature reflective of diurnal cycling in such climates for a given sun exposure duration and concrete mass. Typical sources of elevated concrete temperature are anticipated, with the exception of heat of hydration in early- age concrete, extreme elevated temperature (for example, boiler rooms), and exposure to nuclear radiation in contain- ment structure. Temperature Category B establishes the same long-term temperature as temperature Category A. This temperature is relevant for testing to establish response to sustained load. The short-term temperature remains open- ended, however, and the response of the adhesive anchor to intermediate levels of elevated concrete temperature is established. Products may be tested and assessed for either or both categories under this standard.
8.5.1 Purpose—These service-condition tests are used to assess the sensitivity of the adhesive material to applications in concrete with elevated temperatures that can occur over short periods of time, that is, short-term test temperatures, as well as elevated temperatures that may occur over more extended periods, that is, long-term test temperatures.
8.5.2 General test conditions—Conduct static tension tests at long-term and short-term concrete temperatures corresponding to the desired temperature category (Table 8.1). It shall be permitted to obtain qualification at multiple temperature categories.
8.5.2.1 Conduct confined tension tests in uncracked concrete.
8.5.2.2 Maintain temperature control with thermocouples in accordance with 7.17.2.4. Alternatively, it shall be permitted to correlate the chamber temperature with the test member
internal temperature by separate investigations and control the chamber temperature for the elevated temperature tests.
8.5.2.3 Qualify anchors for one or both of the temperature categories given in Table 8.1. Install and test a minimum of five anchors at each temperature data point. For Temperature Category A, perform tests at the short- and long-term test temperatures. For Temperature Category B, perform tests on anchors—at standard temperature, at the long-term and short-term test temperatures, and at a minimum of two intermediate temperatures between the long-term and short- term temperatures with a maximum increment of 20°C. If the difference between the standard temperature and the selected short-term test temperature is less than 20°C, then testing at intermediate temperatures is not required.
8.5.2.4 Install and cure all anchors at standard temperature. Following the recommended cure period, heat and maintain the test members at the desired temperature for a minimum of 24 hours. Remove each test member from the heating chamber and conduct a confined tension test to failure with continuous measurement of load and displacement before the temperature of the test member falls below the temperature listed in Table 8.1.
8.6—Tension tests with decreased installation temperature
Refer to Table 3.1, Test 8b; Table 3.2, Test 12b; and Table 3.3, Test 9b.
R8.6 These tests establish the suitability of the adhesive anchor system for installation in concrete at lower-than- standard temperatures. All adhesive anchor systems qualified for installation in concrete temperatures below 10°C are required to be installed and tested at the target concrete temperature. When the target temperature for the system to be qualified falls below 5°C, additional tests are required to assess the effect of rising concrete temperatures on the anchor response. The rate of temperature rise is intended to be consistent with sun exposure.
Follow special procedures where the MPII includes them for low-temperature installation conditions. Where preheating of adhesive cartridges to reduce viscosity and facilitate adhesive flow is specified in the MPII, observations should be made to determine whether this results in retarded cure, lowering of the glass-transition temperature, and impaired resistance to creep.
8.6.1 Purpose—These service-condition tests are used to assess the sensitivity of adhesive material to installation in concrete below the standard temperature.
8.6.2 General test conditions—Perform confined tension tests in uncracked concrete for anchors to be installed in Table 8.1—Required temperatures for
testing at long- and short-term elevated concrete temperatures* Temperature category Long-term temperature, Tlt, °C Short-term temperature, Tst, °C A 43 80 B ≥ 43 ≥ Tlt + 11
concrete having a temperature less than 10°C. Prior to installation, condition the anchor rod and test member to the lowest installation temperature and maintain it for a minimum of 24 hours. Install anchors in concrete test members and allow them to cure at the stabilized tempera- ture according to the MPII. Remove the test member from the cooling chamber and tension test the anchors immedi- ately to assure the test members reasonably remains at the conditioned temperature. A thermocouple inserted into the test member may be used to confirm the temperature at the time of testing.
8.6.2.1 When the adhesives are recommended for installation in concrete temperatures below 5°C in addition to the tests described in 8.6.2, perform the following test:
a) Install and test a minimum of five anchors per the MPII. Prior to installation, condition the anchor rod and test member to the target temperature and maintain that temperature for a minimum of 24 hours.
b) Install the anchors in accordance with the MPII and allow them to cure at the stabilized target temperature recommended by the MPII.
c) Apply a constant tension load Nsust,ft as given by Eq. (7-2). Raise the temperature of the test chamber at a constant rate to standard temperature for 72 to 96 hours while monitoring the displacement response for each anchor. A thermocouple inserted into the test member may be used to confirm test member temperatures during the test.
Once the test member attains standard temperature, conduct a confined tension test to failure with continuous measurement of load and displacement.
8.7—Establishment of cure time at standard temperature
Refer to Table 3.1, Test 8c; Table 3.2, Test 12c; and Table 3.3, Test 9c.
R8.7 Cure time of most adhesive compounds is inversely proportional to temperature. Where cure times are provided for temperature ranges that overlap the standard temperature range, a temperature should be selected that corresponds to the lower end of the range.
8.7.1 Purpose—These service-condition tests are used to establish the minimum curing time of the adhesive material for the anchor to achieve full tension capacity.
8.7.2 General test conditions—Perform confined tension tests in uncracked concrete. Tests are conducted on anchors installed in accordance with the MPII at standard temperature. The anchors are allowed to cure for the minimum curing time. Tests are also conducted on anchors installed in the same way and allowed to cure for the time specified in the MPII plus an additional 24 hours.
8.8—Durability assessment
Refer to Table 3.1, Tests 9a and 9b; Table 3.2, Tests 13a and 13b; and Table 3.3, Tests 10a and 10b.
R8.8 Durability tests are intended to assess the response of the adhesive to aggressive exposure conditions. The slice test, where a thin slice of the installed anchor is exposed to a specific environmental condition and then tested for
residual bond strength in the punch test apparatus, provides for a relatively uniform and conservative assessment of the exposure condition by assuring the entire bond layer is subjected to the aggressive compound. Care must be taken in preparation of the slices and punch testing to ensure reliable results. An austenitic stainless steel anchor element of sufficient resistance should be used in the sulfur dioxide tests to avoid steel failure. It does not capture all possible environ- mental exposures deleterious to anchor performance. The two exposure conditions—alkalinity and sulfur—are considered two of the most common and aggressive and, therefore, used as the baseline classification of anchor use.
8.8.1 Purpose—These service-condition tests are used to assess the response of the adhesive material to attack by environmental aggressors. Verify the durability of the adhe- sive material with slice tests. With slice tests, the sensitivity of installed anchors to different environmental exposures can be assessed. The test for exposure to high alkalinity (8.8.2.2.1) is required. The test for exposure to sulfur dioxide (8.2.2.2.2) is optional.
8.8.2 General test conditions—Conduct tests on 13 mm diameter all-thread anchors or the smallest nominal diameter if it is larger than 13 mm. Embed anchors in cylindrical concrete test members having a minimum diameter of 150 mm. Cast the concrete test members in lengths of steel or plastic pipe having a wall thickness as required to prevent slice splitting during punch testing. All test members shall originate from the same concrete batch. Install anchors along the central axis of the concrete test members according to the MPII. For tests in sulfur dioxide, fabricate the anchor element from austenitic stainless steel. After curing the adhesive, concrete cylinders in which the anchors are installed shall be sawn with a diamond saw into 30 mm ± 3 mm thick slices so the resulting slices are undamaged. Slices shall be oriented perpendicular to the anchor axis and consist of the concrete, adhesive material, and anchor element. Discard the top and bottom slices. Prepare a minimum of 10 slices for each environmental exposure to be investigated and 10 reference slices subjected to standard climate conditions.
8.8.2.1 Storage of reference slices—Store the slices under normal climate conditions (dry/standard tempera- ture/relative humidity 50 ± 5%) for 2000 hours.
8.8.2.2 Storage of slices under aggressive environmental
exposure—Store 10 slices each under the following environ-
mental exposures.
8.8.2.2.1 High alkalinity— Store slices under standard climate conditions in a container filled with an alkaline fluid (pH = 13.2). All slices shall be completely covered for 2000 hours. Produce the alkaline fluid by mixing water with potassium hydroxide (KOH) powder or tablets until the pH value of 13.2 is reached. Maintain a mean alkalinity value of pH = 13.2 ± 0.2 during storage. If the measured alkalinity falls below 13.0, extend the test duration by the total length of time during which the pH value was less than 13.0. The length of time the pH was less than 13.0 shall not be included in the calculation of the mean alkalinity value. Monitor the pH value on a daily basis.
8.8.2.2.2 Sulfur dioxide—Perform tests according to EN ISO 6988 (Kesternich Test); the theoretical sulfur dioxide concentration, however, shall be 0.67 percent at the beginning of a cycle, corresponding to 2 dm3 of SO2 for a test chamber volume of 300 dm3. Perform at least 80 cycles.
8.8.3 Punch tests—Within 24 hours after removal of the specimen from storage, measure the thickness of the slices and test them in a test apparatus that permits the metal, that is, the anchor element part of the slice, to be punched through the slice while restraining the surrounding concrete (Fig. 8.1). The loading punch shall act centrally on the metal element. The peak load for each test shall be recorded. Discard results from slices that split during the punch test. Evaluate the bond stress τdur,i for each punch test using Eq. (8-1).
MPa (8-1)
where
hsl = measured thickness of slice i, mm;
da = anchor diameter, mm; and
Nu,i = measured axial load corresponding to failure of slice i, N.
R8.8.3 Slices removed from storage should be tested as soon as possible to avoid the potential effects of specimen drying on the measured bond strength.
8.9—Verification of full concrete capacity in a corner
Refer to Table 3.1, Test 10; Table 3.2, Test 14; and Table 3.3, Test 11.
R8.9 The concrete capacity design method assumes that maximum concrete breakout or bond capacity is reached at edge distances equal to or greater than cac. To check this assumption for a specific anchor system, tests are performed with single anchors in a corner with ca1 = ca2 = cac. This edge distance represents the critical edge distance at which there is no edge influence on the tensile capacity of the anchor as governed by concrete failure. The tests are performed in concrete members having the smallest thickness hmin for which the manufacturer wishes to qualify the anchor. These tests permit the selection of product-specific values for cac that, in conjunction with some value of hmin, will allow anchor installation without damage in the form of splitting cracks to the concrete. There can be more than one combination of these values.
8.9.1 Purpose—This test is performed to determine the critical edge distance cac in test members with the minimum specified thickness for that anchor.
8.9.2 General test conditions—Perform tests on single anchors in uncracked, low-strength concrete at a corner with equal edge distances of cac, and test member thickness hmin (Fig. 8.2).
8.10—Determination of minimum spacing and edge distance to preclude splitting
Refer to Table 3.1, Test 11; Table 3.2, Test 15; and Table 3.3, Test 12. τdur i, Nu i, πdahsl --- =
R8.10 Tests are performed with two anchors installed parallel to an edge with the minimum edge and spacing distances and in a test member having the smallest thickness for which the manufacturer wishes to qualify the anchor. Minimum values for edge distance and anchor spacing are given in ACI 318M, Appendix D. These tests permit the selec- tion of product-specific values for cmin and smin that, in conjunction with some value of hmin, will allow anchor installation without damage in the form of splitting cracks to the concrete. There can be more than one combination of these three minimum values. While the application of torque is not required to set normal adhesive anchor systems, most MPIIs specify a maximum torque value for the clamp attach- ment to the concrete. Use of an elevated torque value (1.7Tinst) is intended to compensate for possible inaccuracies in torque wrenches on site. For conditions in which torque is not applied to the anchor, the minimum edge distance is governed by the drilling process used to install the adhesive anchor.
8.10.1 Purpose—This test is performed to verify for the
smin and cmin requested by the manufacturer that the concrete
will not experience splitting failure during installation and the required tension capacity is achieved.
Fig. 8.1—Punch test.
8.10.2 General test conditions; test anchors in uncracked,
low-strength concrete—Install two anchors at the minimum
spacing smin and the minimum edge distance cmin in test
members with the minimum thickness hmin to be reported for
the anchor. Place the two anchors in a line parallel to the edge of a concrete test element at a distance of at least 3hef
from other groups. Select smin, cmin, and hmin depending on
anchor characteristics.
8.10.2.1 Separate bearing plates shall be permitted to be used for each anchor to simplify the detection of concrete cracking. The distance to the edge of the bearing plate from the centerline of the corresponding anchor shall be three times the diameter da of the anchor being tested.
8.10.2.2 Calculate the expected mean tension failure load corresponding to the edge distance and spacing of the anchor group to be tested considering the service-condition tests and effects of reduced spacing and edge distance. If the average prestressing force corresponding to 1.7Tinst exceeds
the calculated mean tension failure load of the anchor group in uncracked concrete, perform a torque test in accordance with 8.10.2.3. Otherwise, perform a load test in accordance with 8.10.2.4.
8.10.2.3 Torque test—Torque the anchors alternately in increments of 0.2Tinst. After each increment, inspect the
concrete surface for cracks. Stop the test when splitting or steel failure prevents the torque from being increased further. For each test, simultaneously record the torque at first formation of a hairline crack at one or both anchors and the maximum torque that can be applied to the anchors.
8.10.2.4 Load test—Install anchors according to the MPII using the minimum specified spacing and edge distances. Load the anchor group in tension to failure as an unconfined test.
8.11—Tests to determine shear capacity of anchor elements with nonuniform cross section
Refer to Table 3.1, Test 12; Table 3.2, Test 16; and Table 3.3, Test 13.
8.11.1 Purpose—This test is performed to evaluate the shear capacity of anchors as governed by element shear failure in situations where the shear capacity cannot be reliably calculated.
R8.11.1 Where the cross-sectional area of the anchor shear plane is less than a threaded section of the same nominal diameter within five anchor diameters of the shear plane, the shear capacity may be affected by the reduced section. Additionally, shallow anchors that exhibit pullout failure in unconfined tension tests may exhibit shear strengths away from edges that are below those predicted by ACI 318M, Appendix D. Tests shall be performed to estab- lish the appropriate shear capacity in these cases. For anchors assessed for use in cracked concrete and resisting seismic loads, it may be advantageous to establish the reference shear capacity of the anchor system in cracked