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B-1 APPENDIX B Recommended Test Methods for CLSM Introduction mended as a standard method or were beyond the scope of this study One of the most important outputs of this research project is the recommendation of a suite of tests to measure impor- For the purpose of this report, the tests listed in group A, tant CLSM properties. Currently, there are only five ASTM which are existing methods, are referred to by their test des- standard test methods and no AASHTO method for testing ignation (i.e., ASTM D 5971). If these methods are ultimately of CLSM mixtures. Further, some of the existing ASTM test adopted as-is by AASHTO, it is recommended that a new methods may need to be modified to more accurately measure AASHTO designation replace the existing ASTM designa- parameters that can better evaluate properties and characteris- tion. Tests shown in groups B and C (modified and new tests, tics of CLSM. In addition, tests currently used to assess CLSM respectively) are referred to throughout this report generi- vary significantly from one laboratory or agency to another. cally as AASHTO X 1, AASHTO X 2 . . . AASHTO X 10. Table This general lack of suitable test methods intended specifically B-1 shows both the temporary AASHTO designation and the for CLSM was a major concern voiced by state DOTs in the ASTM method upon which the modified method was based. survey distributed as part of NCHRP Project 24-12 and in- It is also recommended that these methods be given an orig- cluded in the Phase I Interim Report for that project. inal AASHTO designation if they are eventually adopted by This appendix describes a suite of test methods that can be AASHTO. Lastly, tests in group D are referred to in this report by used to measure CLSM properties of interest. Different CLSM their actual designations (ASTM, AASHTO, or other), except applications will often require different CLSM properties to be for tests for which no standard test methods exist, which is measured. Only the properties that are deemed important for a designated in Table B-1 as "No standard." given applications should be measured. This appendix repre- Tests shown in group D are methods that the research team sents the recommended test methods (existing, modified, or believes may have potential as standard CLSM methods, but the new) that are capable of measuring a range of CLSM properties. methods were either not included in the investigation or were not studied in enough detail to give adequate guidance. For in- stance, the researchers performed only limited testing using Recommended Test Methods CBR, resilient modulus, and triaxial shear methods. No signif- Based on the findings from the laboratory and field testing icant problems were encountered with these methods, and the programs, various test methods were identified as being ap- research team believes they are applicable for CLSM applica- propriate for evaluating the characteristics and/or properties tions. Other examples of test methods that are recommended of CLSM mixtures. These test methods were divided into four as potential tests for CLSM, but were either not assessed in de- groups (A through D), as characterized in the following list tail or not assessed at all are the TCLP test, which was performed and shown in Table B-1. on several by-product materials in this project, and the Ameri- can Nuclear Society leachate test (ANS 16.1), which was not A. Existing test methods that can be used directly to test performed on any materials in this study (because the materi- CLSM properties als all "passed" the TCLP test). Because of the minimal (or no) B. Modifications of existing test methods emphasis placed on these tests, the methods are not currently C. New test methods proposed to evaluate CLSM being proposed for consideration for AASHTO adoption as D. Potential test methods that could be applicable to CLSM candidate tests for CLSM. Rather, they are being identified as but were not studied in enough detail to be recom- potential tests, worthy of further evaluation.
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B-2 Table B.1. Summary of CLSM test methods. Group Properties/Characteristics Test Methods Descriptions Sampling ASTM D 5971 Existing standard test methods A Flow ASTM D 6103 Setting/hardening AASHTO X 1 Modifications of existing standard (modified ASTM C 403) test methods (except as noted). Unit weight and air content AASHTO X 2 Modifications are described in this (modified ASTM C 231) appendix. Compressive strength AASHTO X 3 (modified ASTM D 4832) pH of CLSM AASHTO X 4 B (modified ASTM G 51) Resistivity AASHTO X 5 (modified ASTM G 57) Freezing and thawing AASHTO X 6 (modified ASTM D 560) Water permeability AASHTO X 7 (modified ASTM D 5084) Corrosion AASHTO X 8 Newly proposed (included in this C Segregation AASHTO X 9 appendix) Subsidence AASHTO X 10 Suitability for load application (ball ASTM D 6024 Potential methods for CLSM; drop) Not experimentally studied or Unit weight, yield, cement content, ASTM D 6023 more testing needed and air content (gravimetric)* California Bearing Ratio (CBR) AASHTO T 193 Resilient modulus AASHTO T 292 Triaxial shear strength USACE EM 1110-2-1906 Dynamic cone penetrometer No standard D Drying shrinkage No standard Direct shear* ASTM D 3080 Thermal conductivity* ASTM D 5334 Consolidation* ASTM D 2435 Air/gas permeability* ASTM D 4525 Total heavy metals in CLSM EPA Method 610 Toxicity Characteristic Leaching EPA Method 1311 Procedure (TCLP) Leachate test ANS 16.1 * Test methods not experimentally studied in research program Group A Test Methods test. The format consists of a brief modification, in which the deletions, substitutions, or additions are highlighted, Test methods in group A are recommended to be adopted along with their section number within the existing method. by AASHTO directly from existing ASTM standard test meth- This modification page would typically be followed by the ods. ASTM D 5971, "Standard Practice for Sampling Freshly standard test upon which it was based. For this report, the Mixed Controlled Low-Strength Material," specifies a proce- brief modifications are provided without the existing stan- dure for obtaining a representative sample of freshly mixed dard methods. The method proposed to measure the pH CLSM for testing as delivered to the project site. This method of CLSM was based in part on a similar ASTM method was employed in the field testing program. (ASTM G 51) but was modified for this research and writ- ASTM D 6103, "Standard Test Method for Flow Consis- ten as a new method in AASHTO format. It is included in tency of Controlled Low Strength Material (CLSM)," was used this group because it is a modified method, but it is written extensively throughout the project, and the results indicate as a new method because of the substantial changes made that this method is applicable and provides a relative value for to the method. CLSM flow. The modifications proposed for each test are provided next, proceeded by a brief discussion on the rationale for the mod- ification(s) for each method. Group B Test Methods Test methods in group B are existing standards that have Setting/Hardening been modified specifically for use with CLSM mixtures. The research team evaluated these methods, and necessary Both a standard needle penetrometer (ASTM C 403) and modifications were made to accomplish objective results soil pocket penetrometer were investigated as part of the lab- for testing of CLSM mixtures. Following the same proce- oratory and field programs. Slight modifications to the needle dure used by AASHTO, modifications were made for each penetrometer test are recommended, as described next.
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B-3 Provisional Method of Test for Setting and Hardening of Controlled Low Strength Material (CLSM) by Penetration Resistance AASHTO Designation: X 1 (2008) ASTM Designation: C 403/C 403M-95 AASHTO X 1 (2008) is identical to ASTM C 403/C 403M-95 except the following: 1. The word "concrete" or "mortar" shall be changed to "CLSM." 2. Sieving of CLSM is not necessary and does not need to be performed. 3. The times of initial and final setting are not determined in this procedure. 4. Practice ASTM C 173 shall be replaced by AASHTO X 2. 5. Add new Section 6.7 to ASTM C 403/C 403M to read as follows: "6.7 Soil pocket penetrometer--The soil pocket penetrometer is a device used to estimate the unconfined compressive strength of cohesive soil in the field. The accuracy is at least 0.5 kgf/cm2. The penetration depth is approximately 6.3 mm." 6. No consolidation of CLSM mixture, as stated in Section 7.7, is needed. 7. Change Section 8.2 of ASTM C 403/C 403M to the following: "for determination of applying consequent constructions or opening to traffic, suitable field penetration apparatus shall be used (note). NOTE--Caution shall be taken when using long needles that may break during use." 8. Change the title of Section 9 of ASTM C 403/C 403M to the following: "9 Procedure A" 9. Add one sentence before the first sentence of Section 9.2 of ASTM C 403/C 403M as follows: "Penetration needles described in Section 6.2 shall be used." 10. The procedure in Section 9.3 of ASTM C 403/C 403M shall not be performed. The penetration resistance values of 500 psi and 4000 psi shall not be used for judgment of initial and final setting. 11. Change Section 9.5 of ASTM C 403/C 403M to the following: "Make at least six penetrations for each time of setting test with time intervals of such duration of 22 to 26 hours." 12. Change Section 10 of ASTM C 403/C 403M to the following: "10 Procedure B 10.1 The same procedure as in Procedure A should be followed, except for the use of a different apparatus. 10.2 The penetration depth is approximately 6.3 mm. Caution shall be taken to eliminate the influence of water and fines, which typically gather on the mixture surface because of bleeding and segregation, on the penetration depth reading. 10.3 Shorter time intervals may be used than those specified in Procedure A as a result of shallower penetration." 13. Change Section 11.2.3 of ASTM C 403/C 403M to the following: "The penetration resistance values from Procedure A can be used to estimate the ultimate bearing capacity of hardening CLSM. The unconfined compressive strength values can be used to determine the opening to traffic or consequent operations." 14. Change Section 12 of ASTM C 403/C 403M to the following: "Precision and Bias are not currently available." Air Content (Pressure Method) often include by-product and off-spec materials as mixture Although there is an existing ASTM standard (D 6023, constituents. The physical properties, such as the specific grav- "Standard Test Method for Unit Weight, Yield, Cement Con- ity, of these materials are often difficult to measure, and vari- tent, and Air Content (Gravimetric) of Controlled Low ations in the physical properties are expected for some raw Strength Material (CLSM)"), the research team concluded materials. Because calculations for determining the air content from the laboratory testing phase that a method for evaluat- of CLSM require physical property values of the constituent ing the air content of CLSM using a pressure method ap- materials, determining the air content following ASTM D proach is necessary. The proposed method is explained in the 6023 is not practical for use as a quality control measure in the following paragraph. field. Thus, an alternative method using the pressure approach A significant degree of technical difficulty occurs when is proposed. This method is a modification of ASTM C 231 ASTM D 6023 is used for CLSM mixtures. CLSM mixtures and was used throughout this research project.
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B-4 Provisional Method of Test for Air Content of Freshly Mixed Controlled Low-Strength Material (CLSM) by the Pressure Method AASHTO Designation: X 2 (2008) ASTM Designation: C 231-97 AASHTO X 2 (2008) is identical to ASTM C 231-97 except for the following: 1. Change Section 1.4 of ASTM C 231-97 to the following: "The values stated in SI units are to be regarded as the standard." 2. Change Section 7.1 of ASTM C 231-97 to the following: "Obtain the sample of freshly mixed CLSM mixture in accordance with applicable procedures of ASTM D 5971." 3. Change Section 8.1.1 to 8.1.3 of ASTM C 231-97 to the following: "Dampen the interior of the measuring bowl and place it on a flat, level, firm surface. Place a representative sample of the CLSM, prepared as described in ASTM D 5971, in the measuring bowl until it is completely full." Compressive Strength Test Cylinders," is often specified and used by researchers and engineers. But, as discussed in Chapter 3, some modifi- ASTM D 4832, "Standard Test Method for Preparation cations are needed to measure compressive strength of CLSM and Testing of Controlled Low Strength Material (CLSM) specimens accurately and in a repeatable manner. Provisional Method of Test for Preparation and Testing of Controlled Low Strength Material (CLSM) Test Cylinders AASHTO Designation: X 3 (2008) ASTM Designation: D 4832-95 AASHTO X 3 (2008) is identical to ASTM D 4832-95 except for the following: 1. Change the last sentence of Section 5.3 of ASTM D 4832-95 to the following: "Other tests that can be used during construction for quality control of CLSM are Test Methods X 1, X 2, and X 3." 2. Change Section 6.1 of ASTM D 4832-95 to the following: "6.1 Single-Use Cylindrical Molds--Plastic single-use molds with the length to diameter ratio of 2 to 1 and with tight-fitting lids, conforming to ASTM C 470. Other sizes and types of molds may be used as long as the length to diameter ratio is 2. The plastic molds may be prepared by cutting the opposite sides from top to bottom and then using tape to bind the mold back to its original shape." 3. Change Section 6.2 of ASTM D 4832-95 to the following: "6.2 Sampling and Mixing Receptacle--The receptacle shall be a suitable heavy-gage container, wheelbarrow, etc. of sufficient capacity to allow easy sampling and mixing and to allow preparation of at least three cylinders and for other tests such as described in Test Methods X 1, X 2, and X 3." 4. Change Section 6.3 of ASTM D 4832-95 to the following: "6.3 Testing Machine--The testing machine shall meet the requirements as described in AASHTO T 22-97 or T 208-96." 5. Add the following note after Section 7.2.2 of ASTM D 4832-95: "Note: Lightly rotating the solidified sulfur cap from the CLSM samples is a suitable approach to release the sulfur cap from the capping plate." 6. Change the first sentence of Section 10.1 of ASTM D 4832-95 to the following: "After seven days of curing, the specimen shall be removed from the mold. Careful attention shall be paid such that speci- mens are not damaged. If leaching of hydration products from CLSM specimens is a potential problem, cylinders shall not be stripped until the day of testing. The samples should be kept moist until the time of testing. No drying time before testing is required."
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B-5 7. Add the following note after Section 10.1.3 of ASTM D 4832-95: "Only elastomeric pads with a Shore A durometer hardness of 50 or less shall be used for testing CLSM cylinders. The pad material is not limited to neoprene type." 8. Change the second sentence of Section 11.2 of ASTM D 4832-95 to the following: "When a testing machine meeting requirements as described in AASHTO T 22-97 is used, apply the load at a constant rate such that the cylinder will fail in not less than 2 min. When a testing machine meeting requirements as described in AASHTO T 208-96 is used, apply the displacement at a constant rate of 0.25 to 0.64 mm/min." Measuring pH values of CLSM pH of Soil for Use in Corrosion Testing," is the test method typically used for evaluating the pH of soils. Because CLSM The pH of CLSM is one parameter used to evaluate the cor- requires special crushing prior to testing, a modified version rosion susceptibility of metal samples embedded in soil or of ASTM G 51 has been developed. The proposed AASHTO CLSM. ASTM G 51, "Standard Test Method for Measuring X 4 (2004) is a new method, mainly based on ASTM G 51. Provisional Method of Test for Measuring pH of Controlled Low Strength Material (CLSM) for Use in Corrosion Testing AASHTO DESIGNATION: X 4 (2008) ASTM Designation: ASTM G 51-95 1 Scope 1.1 This test method covers a procedure for determining the pH of a CLSM mixture for corrosion testing. The principal use of the method is to supplement other CLSM characteristics (resistivity, chloride concentration, etc.) to identify condi- tions under which the corrosion of metals embedded in CLSM may be accentuated. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsi- bility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2 Referenced Documents 2.1 ASTM Standard A 674, "Standard Practice for Polyethylene Encasement for Ductile Iron Pipe for Water or Other Liquids" E 177, "Practice for Use of the Terms Precision and Bias in ASTM Test Methods" E 691, "Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method" G 57, "Standard Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method" 2.2 Other Standards ANSI/AWWA C 105/21.5 American National Standard for Polyethylene Encasement for Ductile Iron Pipe for Water or Other Liquids 3 Significance and Use 3.1 Information on the pH of CLSM can be used as an aid in evaluating the potential corrosivity of pipe in a CLSM mixture environment. 4 Apparatus 4.1 pH Meter--A portable, battery-powered pH meter is necessary for field measurements. Most instruments can also func- tion as a high-impedance voltmeter. An LCD display is preferred for readability in a bright, outdoor environment. A portable or benchtop model can be used for laboratory determination of the pH. 4.2 Calomel and Glass Electrodes 4.2.1 Use a saturated calomel reference electrode or its equivalent to determine the pH of a CLSM. A few crystals of solid potas- sium chloride should always be present within the chamber surrounding the calomel to assure that the solution is saturated
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B-6 under the conditions of use. The design of the electrode must permit the formation of a fresh liquid junction between the solution of potassium chloride and the buffer or test specimen for each test and allow traces of the CLSM to be readily removed by washing. 4.2.2 A glass electrode of rugged construction is required. The performance of the glass electrode is satisfactory if it furnishes the correct pH value (± 0.1 pH unit) for standard buffered solutions. 4.2.3 A combination electrode consisting of a saturated calomel reference electrode and a glass electrode (4.2.1 and 4.2.2) combined as a single electrode is acceptable. However, the requirements outlined above are equally applicable to the electrodes used in this combination unit. 4.3 Temperature Compensation--Some pH electrodes have temperature compensation built in as part of the pH electrode. A thermometer of rugged construction is required if temperature compensation is not available as part of the pH elec- trode system. A stainless steel sheathed thermometer is preferred. 5 Reagents and Materials 5.1 During the calibration procedure for the pH meter, standard buffered solutions of known pH are necessary. These solutions, or tablets to make up these solutions, can be purchased from chemical supply companies or pH equipment manufacturers. 6 Sampling 6.1 By the nature of the measurement, pH is determined for a small volume of CLSM pore solution. Thus, it is important that at least three measurements from three different samples with the same mixture constituents and proportions and from the same batch be obtained and a simple average calculated. 7 Calibration and Standardization 7.1 Test for Linearity--Prior to field use, or periodically when used extensively in the field, test the pH measuring apparatus for linearity of response. This procedure is as follows: 7.1.1 Turn on the instrument, allow it to warm up thoroughly, and bring it to electrical balance in accordance with the man- ufacturer's instructions. Before use, clean and rinse the glass and calomel electrodes in distilled water. 7.1.2 At least two standard buffered pH solutions that span the anticipated CLSM pH to be measured are required. From prac- tical experience, standard solutions of pH 4, 7, and 8 are recommended. For the test, the temperature of these solutions shall not differ from each other by more than 5°C. A laboratory thermometer can be used for these measurements. 7.1.3 Adjust the temperature-compensating dial on the pH meter to the standard solution temperature. 7.1.4 Immerse the electrodes in a small volume of the first known standard solution. Now adjust the pH meter to read this known pH. 7.1.5 Remove the electrodes from the first standard solution, and rinse in distilled water. Immerse the electrodes in the second known standard solution and read the pH value. Judge the system to be operating satisfactorily if the reading obtained for the second standard agrees within +/- 0.1 unit of the assigned pH. 7.2 Calibration of pH Meter--Calibrate the pH meter immediately before use. If a series of measurements are to be made, repeat the calibration procedure at intervals of about 30 min. Perform the pH meter calibration as follows: 7.2.1 Use a standard pH solution in the range of the pH of the CLSM to be tested, if such information is known beforehand. Otherwise, begin with a standard solution having a pH of 7. Stabilize the temperature of the solution so that it matches the temperature of the CLSM to within 10°C. 7.2.2 Immerse the electrodes in the known standard solution and calibrate the meter in accordance with the manufacturer's instructions. 8 Procedure 8.1 Preparation for pH Determination of CLSM 8.1.1 For evaluating the pH of in-place CLSM, the pH measurement should be made in the field with the glass electrode con- tacting the CLSM at the specific depth of interest. If the surface CLSM pH is desired, then the CLSM can be broken up so as to accept the electrodes. Existing loose material on the surface shall be removed from the surface and shall not be used for evaluating the pH. If a subsurface pH is desired, then a boring or an excavation must be done so that the elec- trode can be placed in the CLSM at the desired depth. After boring through the CLSM to the depth of interest, carefully break up the material at the desired reading depth with the boring tip. Then lower the probe into the cavity for testing.
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B-7 8.1.2 The crushed CLSM sample can be brought to the surface with a boring tool or a post-hole digger, and the measurement made in the field on the CLSM obtained. 8.1.3 The least desirable pH measurement of CLSM is that which is based on a CLSM sample transported to a laboratory for evaluation. However, if the pH must be measured in the laboratory, then make the pH measurement as quickly as pos- sible after the CLSM sample is taken from the field. Place the sample in a clean, airtight glass container or plastic bag so that the CLSM is not in contact with any metal. If the pH measurement is not made within 24 hours from the time the sample is obtained in the field, then it is recommended that the sample be packed in dry ice to retard any change in pH due to chemical or biological reactions. Make the pH measurement on the CLSM at room temperature and as received. 22.214.171.124 Depending on the moisture content of the sample, some water may have to be added to the sample obtained in the field. 126.96.36.199 If the CLSM sample is frozen, it must be allowed to thaw prior to making the measurement. 8.2 Determination of pH of CLSM 8.2.1 Complete the meter calibration procedure (7.2). The standard solution temperature must match the temperature of the CLSM within 10°C. The temperature of the CLSM can be determined by inserting a metal-sheathed thermometer into the crushed CLSM to the depth of interest. 8.2.2 Clean the electrode surface by washing it with distilled water. 8.2.3 Press the contact area of the glass electrode or combination electrode, as the case may be, against the CLSM at the location of interest. This step is important since poor contact or electrode movement can affect the stability of the measurement. 8.2.4 The reference electrode should be placed in contact with the crushed CLSM near the glass electrode (this step is not required when using a combination electrode). An electrode separation of about 300 mm (1 ft) is suggested for surface measurements. For subsurface readings, the reference electrode may be placed on the surface about 300 mm from the bore hole entry. 8.2.5 With the electrode(s) in place, set the meter to read pH, allowing 1 or 2 minutes for equilibrium to be established, then take the meter reading. 8.2.6 After approximately 1 min, repeat the reading. In general, the values will agree within 0.2 pH units. If the range of values is as large as 0.4, then repeat 8.1.1 and, if necessary, Section 7. If the problem persists, check your equipment to verify that it is operating properly, and check your measurement technique as described in Procedure, Section 8, in this test method. 9 Laboratory Procedure 9.1 Samples tested in the laboratory shall be crushed and placed in a non-conductive container. If the CLSM sample is dry, some water may be required to obtain a stable pH reading. 9.2 Follow the procedures outlined in sections 8.2.1, 8.2.2, 8.2.3, 8.2.5, and 8.2.6. 10 Keywords 10.1 corrosion of metals in CLSM, pH of CLSM, measurement of pH, test method for CLSM pH, field measurement of pH, CLSM pH for corrosion testing, underground corrosion. Measuring Resistivity of CLSM Specimens for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method," is an adequate test method to The resistivity is another parameter that may be used to evaluate the resistivity of CLSM. The only proposed change evaluate the corrosion susceptibility of metal samples em- is to change all references to the soil from "soil" to "soil and bedded in soil or CLSM. ASTM G 57, "Standard Test Method CLSM." Provisional Method of Test for Field Measurement of Soil and Controlled Low-Strength Material (CLSM) Resistivity Using the Wenner Four-Electrode Method AASHTO Designation: X 5 (2008) ASTM Designation: G 57-95a AASHTO X 5 (2008) is identical to ASTM G 57 except for the following: 1. Change the word "soil" to "soil and CLSM" throughout the test method.
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B-8 Freezing and Thawing Testing only requires slight modifications to estimate the behavior of CLSM specimens under freezing and thawing cycles. The re- Because of the similarity of CLSM and compacted soil- search team proposes that ASTM D 560 be modified for eval- cement mixtures, ASTM D 560, "Standard Test Methods for uating the relative performance of CLSM when exposed to Freezing and Thawing Compacted Soil-Cement Mixtures," freezing and thawing cycles. Provisional Method of Test for Freezing and Thawing CLSM Mixtures AASHTO Designation: X 6 (2008) ASTM Designation: D 560-96 AASHTO X 6 (2008) is identical to ASTM D 560-96 except for the following: 1. Change Sections 4.1, 4.2, 4.3, 4.8, 4.10, 4.11, 4.12, 4.13, and 4.18 of ASTM D 560-96 to the following: "Specimen--Cylindrical CLSM specimens with a diameter of 102 mm and a height of 102 to 127 mm should be used in this testing." 2. Change title of Section 5 of ASTM D 560-96 to the following: "Procedure" 3. Change Sections 5.1 and 5.2 of ASTM D 560-96 to the following: "Sampling--Prepare specimens of size described in Section 4.1." 4. Change Section 5.3.1 of ASTM D 560-96 to the following: "At the end of the storage (7 days or 28 days) in the . . . and remove." 5. Change last sentence of Section 5.3.2 of ASTM D 560-96 to the following: "Weigh the specimen." 6. Ignore Sections 5.3.3 and 5.3.4 of ASTM D 560-96. 7. Ignore Note 4 of 560-96. 8. Ignore Section 5.3.6 ASTM D 560-96. 9. Ignore Section 5.3.8 ASTM D 560-96. 10. Ignore Section 6 of ASTM D 560-96. 11. Ignore Sections 7.1.1 to 7.1.3 of ASTM D 560-96. 12. Ignore Section 9 of ASTM D 560-96. Water Permeability the typical practice of checking the B value (e.g., B > 0.95) for saturation is not applicable or recommended because CLSM Even though water permeability testing was performed for specimens are usually stronger and less compressible than soil only six CLSM mixtures, the method was deemed to be ap- samples and act more like rock cores, where the B values may plicable and the values obtained were compatible with those remain nearly unchanged after applications of high back found in the literature. Thus, ASTM D 5084 is being recom- pressures. The proposed recommended test method is pre- mended for adoption by AASHTO. When using this method, sented below in AASHTO format. Provisional Method of Test for Measurement of Hydraulic Conductivity of Saturated CLSM Mixtures Using a Flexible Wall Permeameter AASHTO Designation: X 7 (2008) ASTM Designation: D 5084-96 AASHTO X 7 (2004) is identical to ASTM D 5084-96 except for the following: 1. Change Note 8 of Section 188.8.131.52 of ASTM D 5084-96 to the following: "Note 8--The B coefficient is defined for this type of test as the change in pore water pressure in the porous material divided by the change in confining pressure. Because CLSM is relatively incompressible, saturated materials have B values that are somewhat less than 1.0. The specimen is deemed as sufficiently saturated if the B values remain nearly unchanged with changes in confining pressure."
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B-9 Group C Test Methods · AASHTO X 8, "Evaluating the Corrosion Performance of Samples Embedded in Controlled Low-Strength Material The research conducted in this project resulted in the (CLSM) via Mass Loss Testing" development of three new provisional test methods that · AASHTO X 9, "Determining the Potential for Segregation can be used to evaluate CLSM. These methods, referred in Controlled Low-Strength Material (CLSM) Mixtures" to by their temporary AASHTO designations, are listed · AASHTO X 10, "Evaluating the Subsidence of Controlled below: Low-Strength Material (CLSM) Mixtures" Provisional Method of Test for Evaluating the Corrosion Performance of Samples Embedded in Controlled Low Strength Material (CLSM) via Mass Loss Testing AASHTO Designation: X 8 (2008). 1 Scope 1.1 This test method covers a procedure for determining the performance of metallic samples embedded in CLSM mixtures. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regula- tory limitations prior to use. 2 Referenced Documents 2.1 ASTM Standards G 1, "Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens" D 4832, "Standard Test Method for Preparation and Testing of Controlled Low Strength Material (CLSM) Test Cylinders" C 192, "Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory" C 496, "Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens" 2.2 Other Standards 3 Significance and Use 3.1 The environment in which the metallic sample is exposed directly impacts underground corrosion of metallic samples. This test method provides a method to compare the corrosion performance of metallic samples embedded in CLSM. A control sample made with locally available soil materials can be fabricated and tested for comparative purposes. 4 Apparatus 4.1 Metallic Coupons 4.1.1 The intent of this test is to determine the influence of the surrounding materials (i.e., different CLSM mixtures or soil) and environment on the corrosion performance of metallic coupons embedded in them. When comparing the influence of surrounding materials, metallic coupons shall be obtained from the same lot of material. 4.1.2 Metallic coupons shall be approximately 13 mm by 25 mm. The thickness of the coupon will depend on the type of metal- lic material. 4.1.3 A 2 mm hole shall be drilled through the coupon within 5 mm of the shorter edge and at the midpoint between the long edges. 4.1.4 The metallic coupons shall be cleaned and weighed (following ASTM G 1 test procedures) prior to placement into the CLSM (or control sample). 4.2 Mold 4.2.1 A single-use plastic cylindrical mold shall be used. 4.2.2 The mold shall be cut on opposite sides along the longitudinal axis from the top opening of the mold to the bottom of the mold. Do not cut the bottom of the mold. 4.2.3 Carefully align the mold back into its original shape and place tape around the outer cylinder circumference to hold the cylinder in its original shape. Additional tape may have to be placed along the cut lines to prevent leakage during casting.
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B-10 4.3 Sewing Thread--Heavy-duty sewing thread will be used to suspend the coupons in the plastic cylindrical molds prior to testing. Threads shall be cut into lengths of approximately 200 mm. 4.4 Testing Machine--The testing machine shall conform to the specifications of ASTM C 39. 4.5 Holding Tank--The holding tank shall be non-metallic and shall be large enough to expose all samples from the study at the same time. The sides of the holding tank shall be high enough to ensure proper exposure conditions. 5 Reagents and Materials 5.1 Depending on the exposure conditions, several different types of chemicals may be used. Calcium chloride has been used to mimic chloride-containing soils. 6 Sampling 6.1 A minimum of three samples shall be cast per coupon type. 7 Sample Preparation 7.1 Suspend the metallic coupons in the plastic molds as shown in Figure B.1. Ensure that a cover of 38 mm is obtained (from the top of the metallic coupon to the top of the cylinder). The mass of the metallic coupons should be marked on the outer surface of the cylinder. 7.2 Mixing of the CLSM shall be performed according to ASTM D 4832. 7.3 Place the CLSM (or soil) into the mold, being careful to not move the metallic coupon from the center of the plastic mold. Corrosion performance may be dependent on the amount of cover and can significantly influence the corrosion suscep- tibility of the metallic coupon. 7.4 Follow the recommended procedure in ASTM C 192 to cure the samples immediately after casting. Soil samples do not require curing. 7.5 If sand or other soil types are being used as a control, approximately 25 holes shall be drilled around the perimeter of the plastic mold to ensure exposure of the soil to the solution environment. Holes should be covered with a semi-permeable material to allow solution to pass and to keep the soil in the mold. 8 Cylinder Exposure 8.1 After curing, remove the tape from the outside of the plastic mold and carefully separate the mold from the CLSM sample. 8.2 Place the sample into the test solution, ensuring that the solution depth is 100 mm (50 mm of exposed sample). This depth shall be maintained throughout the test period. 8.3 All samples being compared shall be placed in the same holding tank container to ensure similar exposure conditions and solutions. 8.4 Samples shall be exposed for a minimum of 180 days. Longer exposure periods are allowable, but all samples shall be eval- uated for mass loss at the same exposure time. 9 Mass Loss Testing 9.1 After the exposure period has elapsed, the coupons can be removed from the CLSM by placing the CLSM specimen in a testing machine and loading similar to ASTM C 496. 9.2 Follow ASTM G 1 to clean the sample and obtain the mass loss. 38 mm coupon 100 mm solution 75 x 150mm depth cylinder CLSM or sand Figure B.1. Sample layout.
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B-11 10 Reporting 10.1 Report the mass loss as a percentage of the original weight of the metallic coupon. The percent mass loss can be determined as follows: M original - M corroded Percent Mass Loss = · 100 M original where Moriginal = the mass of the metallic coupon prior to embedment into the CLSM or soil sample. Mcorroded = the mass of the metallic coupon after removal from the CLSM or soil sample. NOTE--Corrosion damage may also be reported as corrosion rate by using the mass loss and the conversion formula pro- vided in ASTM G 1. 10.2 Comparisons shall be made between the mass loss (corrosion rate) of the metallic coupon embedded in soil (the control sample) and between the coupons embedded in CLSM. NOTE--In case galvanic corrosion of the metallic material is expected due to exposure of the metal partly to the tested CLSM mixture and partly to a soil, average percent mass loss of the metallic material exposed to soil should be expected to be approximately 25 and 35 times higher than the measured average percent mass loss for sands and clays, respectively. 11 Keywords 11.1 corrosion, CLSM. Provisional Method of Test for Determining the Potential for Segregation in Controlled Low-Strength Material (CLSM) Mixtures AASHTO Designation: X 9 (2008) 1 Scope 1.1 This test method covers a procedure for determining the susceptibility of a CLSM mixture to segregate during hardening. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2 Referenced Documents 2.1 ASTM Standards C 136, "Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates" D 4832, "Standard Test Method for Preparation and Testing of Controlled Low Strength Material (CLSM) Test Cylinders" 3 Significance and Use 3.1 Information on the potential segregation of CLSM mixtures can be determined. Segregation of CLSM may result in non- uniform properties and characteristics. It is not the objective of this proposed standard that all CLSM mixtures be tested for segregation. If unique requirements or materials are needed, segregation testing may be necessary. 4 Apparatus 4.1 Segregation Mold--A mold, as shown in Figure B.2, shall be used to determine the degree of segregation of CLSM mixtures. 4.2 Tamping Rod--A round, straight 10 mm diameter steel rod, 300 mm in length and having both ends rounded to a hemi- spherical tip of radius 5 mm. 4.3 A set of aggregate sieves, including sizes 9.5 mm, No. 4 (4.75 mm), No. 8 (2.36 mm), No. 16 (1.18 mm), No. 30 (600 m), No. 50 (300 m), and No. 100 (150 m). If an aggregate with a maximum aggregate size (MAS) larger than 9.5 mm is used, include all sieves as specified in ASTM C 136 up to a size that is one size larger that the MAS for the mixture.
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B-12 150 mm TOP VIEW Separation Plate (see notes 75 mm for description and dimensions) 225 mm 75 mm Separation Plate (see notes for description and dimensions) Note: The separation plate is a 1.5 mm thick steel plate 113 mm x 225 mm. A center point of a 100 mm hole is centrally located along the longitudinal axis and 75 mm from one 100 mm edge. ELEVATION VIEW Figure B.2. Segregation mold. 5 Procedure 5.1 Both segregation plates on the segregation mold shall be placed such that the 100 mm hole is aligned with the inside diam- eter of the mold. 5.2 CLSM segregation samples shall be prepared following Sections 9.1 and 9.2 of ASTM D 4832. 5.3 Approximately 20 minutes prior to the initial set or 2 hours after placement (whichever is sooner), the segregation mold shall be separated into thirds. Force the segregation plates into and through the sample. Special care shall be taken that no material is lost during mold separation. 5.4 Order the sieves from maximum size on top to minimum size on bottom. The smallest sized sieve in the set shall be a No. 100 sieve. 5.5 Extract the fresh CLSM from the upper third of the mold into the maximum sized sieve. Ensure that all aggregate and paste is removed from the segregation mold by gently washing the sides of the mold into the sieve stack. 5.6 Continue to place water onto the CLSM in the upper sieve. After the aggregates have been washed and no additional aggre- gates are being washed through the top sieve, carefully remove the top sieve and its contents and begin placing water on the CLSM in the next sieve. Ensure that all aggregates are clean at this level and continue this process for each successive sieve. Care shall be taken to not spill any aggregate from the cleaned aggregates in the sieves. In addition, care shall be taken to not overload one sieve such that large amounts of aggregate and water are retained on the sieve. If too much aggregate is retained
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B-13 on one sieve, the washing water will overflow and material will be lost. To avoid such overflow, separate sieves intermittently and inspect for possible backup. If the aggregate and cement are inhibiting the flow of water through the sieve, remove the sieve and re-establish flow. 5.7 After all aggregate on each sieve has been cleaned, dry the aggregates and perform a sieve analysis for the upper third, cen- ter third, and lower third of the segregation mold. 6 Analysis 6.1 Plot the sieve analysis from CLSM retained in the upper, middle, and lower one-third of the segregation mold. The per- centage retained (or passed) for each mold section can then be compared. 6.2 No recommendations are available yet on the potential change in material properties and/or characteristics resulting from segregation of CLSM. 7 Keywords 7.1 segregation, CLSM, sieve, mold. Provisional Method of Test for Evaluating the Subsidence of Controlled Low-Strength Materials (CLSM) AASHTO Designation: X 10 (2008) 1 Scope 1.1 This test method covers a procedure for determining the subsidence of CLSM mixtures. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2 Referenced Documents 2.1 ASTM Standards D 4832, "Standard Test Method for Preparation and Testing of Controlled Low Strength Material (CLSM) Test Cylinders" 3 Significance and Use 3.1 Subsidence of CLSM occurs when the fresh CLSM mixture loses water and entrapped air through bleeding and absorption into the surrounding soil. Significant subsidence may require additional labor and materials to offset its effects. Also, know- ing the subsidence of a CLSM mixture can assist the contractor in placing the fresh CLSM such that after setting (i.e., after the subsidence has taken place), the material will be at the final required grade. 4 Apparatus 4.1 Subsidence Mold--The subsidence mold shall be a 100 mm diameter by 600 mm tall plastic cylinder. The cylinder shall be discarded after one use. 4.2 Subsidence Gage--The subsidence gage is used to measure the drop in the CLSM surface with respect to the top of the cylin- der. Figure B.3 shows the subsidence gage. 5 Sample Preparation and Testing 5.1 Mix and cast the CLSM as specified in ASTM D 4832. 5.2 Immediately after filling the cylinder, strike off excess CLSM from the surface to obtain a flat even surface. 5.3 Prior to testing, place the gage on a flat surface and measure the distance, d1, from the tip of the gage to the inside bottom of the subsidence gage. 5.4 Wait 15 minutes and place the subsidence gage on the top of the cylinder. Release the knurled nut and gently lower the pin to the surface of the CLSM. Tighten the knurled nut and measure the distance from the tip of the pin to the inside bottom of the subsidence gage, dn, where n is the measurement number.
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B-14 Swagelok connector with knurled nut and teflon ferrules 18 mm cylinder Measuring pin Swagelok connector with knurled nut and teflon ferrules 100 mm cylinder 125 mm Figure B.3. Subsidence gage layout. 5.5 Measurements shall be made near the center of the sample away from the edges. Where heavy bleeding occurs, the bleed water shall be removed from the top surface using a large-tip transfer pipette prior to measurement. Maintain a record of the time after mixing. 5.6 Evaluate the sample every 15 minutes as discussed in Sections 5.4 and 5.5 until the sample has reached initial set. 6 Reporting 6.1 Report the maximum value of subsidence as follows: dn - d1 Subsidence = 0.6 meters Report the subsidence value with the mixture designation and mixture proportions. 7 Keywords 7.1 subsidence, CLSM. Group D Test Methods Suitability for Load Application As previously mentioned, inclusion in this group does not ASTM D 6024, "Standard Test Method for Ball Drop on indicate that these test methods are not important. Rather, Controlled Low Strength Material (CLSM) to Determine such inclusion indicates only that these test methods were not Suitability for Load Application," has been used to some ex- investigated in this research project and/or more detailed re- tent in CLSM construction. As this method is for field prac- search is needed before they can be adopted as AASHTO tice, it was not evaluated as part of the laboratory testing pro- methods. The following subsections briefly discuss each gram. For many applications, determining the suitability of method. load applications is essential and will be included as part of
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B-15 the field testing plan. The research team attempted to corre- difficult. The researchers expect this method, along with pos- late the diameter of indentation of ball drop with penetration sibly CBR and resilient modulus test methods, may eventu- values for different CLSM mixtures in selected field tests but ally be recommended for adoption by AASHTO. was not successful. The influence of surface bleed water de- serves additional attention to determine if it affects subse- quent measurements. Field tests showed that this method was Dynamic Cone Penetrometer too demanding for CLSM mixtures to meet the 76 mm dent The dynamic cone penetrometer (DCP) was used in this diameter requirement. Instead, a dent diameter of 90 mm was project to estimate the excavatability of CLSM mixtures and deemed acceptable. appears to show promise for this application. The DCP is a modified and simplified version of the penetrometer used by Unit Weight, Yield, Cement Content, the Country Roads Board, Victoria, Australia. It is used by geo- and Air Content technical engineers to obtain an index of in-situ CBR and to estimate the strength of soil as a function of depth. The test- ASTM D 6023, "Standard Test Method for Unit Weight, ing consists of dropping a hammer (8 kg in weight) from a Yield, Cement Content, and Air Content (Gravimetric) of height of 575 mm, which forces a steel rod with conical head Controlled Low Strength Material (CLSM)," was not incor- into the CLSM or soil. The penetration depth per blow was porated into the laboratory testing program. Because of the recorded. The corresponding DCP index value can be used to complex calculations involved and the potential lack of de- estimate a soil strength value (CBR). sired inputs and values (e.g., specific gravity), the method is not likely to be adopted as an AASHTO method. Interested practitioners may use it as a check for the proposed pressure Drying Shrinkage method, AASHTO X 2. This test method was used to evaluate the drying shrink- age of CLSM mixtures and was adopted from European California Bearing Ratio practice. The molds for this testing were specially made for this project and knowledge of this test method is limited Specimens from only six CLSM mixtures were tested for within the United States. As a result of the lack of availabil- CBR values at the age of 28 days according to slightly modified ity of the test molds and the lack of experience with this AASHTO test method T 193. In general, the test method was method, this method is not recommended for further test- performed without difficulty. However, because CLSM mix- ing. Interested readers may refer to Katz et al. (2002) for tures are generally much stronger than soil, more research is more information on this topic. Their research demon- needed to verify the suitability of this test method. Interested strated the significant effect of the fineness, shape, surface parties may refer to the testing and preliminary findings de- structure, and relative content of the waste (e.g., dust from scribed in Chapter 3 of this report. cement kiln and asphalt plants) on the volume changes, both at early age and later ages. Resilient Modulus Direct Shear AASHTO T 292, "Resilient Modulus of Subgrade Soils and Untreated Base/Subbase Materials," was used to evalu- Although direct shear testing was not experimentally eval- ate six CLSM specimens. Because of the limited amount of uated in this program, it has been evaluated by other re- testing, future research is needed to draw conclusions from searchers. ASTM D 3080, "Standard Test Method for Direct this testing. Shear Test of Soils under Consolidated Drained Conditions," is often used for this purpose. Triaxial Shear Strength Thermal Conductivity A testing procedure from the U.S. Army Corps of Engi- neers, EM 1110-2-1906, was used in this study to determine Thermal properties of CLSM mixtures may be important the cohesion and internal friction angles of six CLSM mix- for underground piping applications such as pipes carrying tures. This procedure was determined to be feasible for eval- hot water. Because of the limited scope of this research uating the triaxial properties of CLSM mixtures tested in the project, the thermal properties of CLSM were not evalu- laboratory program, but its limited inclusion in the testing ated. Related testing information can be found in ASTM D program makes recommending it as a standard test method 5334, "Standard Test Method for Determination of Thermal
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B-16 STEP 1: Chemical analysis of all raw materials STEP 2: Less than Heavy metal test of all raw materials using EPA 610 TCLP limits STEP 3: Raw materials deemed non-toxic. TCLP test (Method 40CFR 261.24) Less than Accepted to be used in CLSM on potentially toxic raw materials mixtures. TCLP limits from Step 2 STEP 4: TCLP test (Method 40 CFR 261.24) Less than on CLSM mixture containing potentially toxic raw materials from TCLP limits Step 3 Higher than TCLP limits Raw materials deemed toxic. Rejected to be used in CLSM mixtures. Figure B.4. Proposed flowchart to study toxicity of CLSM constituent materials. Conductivity of Soil and Soft Rock by Thermal Needle Probe Leaching/Environmental Impact Procedure." An entire procedure, shown in Figure B.4, has been pro- posed to evaluate constituent raw materials for potential leach- Consolidation ing of heavy metals. This approach can be used as a reference for engineers unfamiliar with toxicity testing. The consolidation of CLSM mixtures may be important for various applications, such as pavement base/subbase and bridge approach fill. ASTM D 2435, "Standard Test Method for Conclusion One-Dimensional Consolidation Properties of Soils," can be This appendix provided guidance on various CLSM test consulted if deemed necessary for a specific application. Con- methods. Selected methods described in this appendix were solidation was not evaluated as part of this research project. used in the field testing program. The test methods recom- mended should be evaluated by practitioners and their feed- Air/Gas Permeability backs may be included in the continuous development of these methods. Air/gas permeability of CLSM mixtures may be important for backfill applications, especially when natural gas pipes are embedded in the CLSM. If a pipe leaks, a CLSM mixture with Reference low permeability could make detecting the location of the leak Katz, A., Kovler, K., and Schamban, I. (2002). "Early-Age Shrinkage and difficult. Based on the literature review, air permeability of Cracking of Controlled Low-Strength Materials (CLSM)." Early CLSM mixtures can be evaluated using ASTM D 4525, "Stan- Age Cracking in Cementitious Systems, RILEM Proceedings, PRO 23, dard Test Method for Permeability of Rocks by Flowing Air." pp. 373381.