Methods for Evaluating Fly Ash for Use in Highway Concrete (2013)

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B-1 These proposed test methods are the suggestions of the NCHRP Project 18-13 research team. These test methods have not been approved by NCHRP or any AASHTO committee nor formally accepted for the AASHTO Specifications. Contents B-2 Determination of the Foam Index of a Coal Fly Ash and Portland Cement Slurry B-9 Proposed Modifications to ASTM D4607 for Determining the Iodine Number for Coal Fly Ash B-14 Determination of Air-Entraining Admixture Adsorption by Coal Fly Ash A T T A C H M E N T B Draft Proposed New Test Methods

B-2 Proposed Method of Test for Determination of the Foam Index of a Coal Fly Ash and Portland Cement Slurry 1. SCOPE This test method is for the determination of the foam index of a mixture of coal fly ash, portland 1.1. cement, water, and an air-entraining admixture. The foam index can be used as a relative measure of the effect of a specific coal fly ash on the 1.2. process of air entrainment in concrete batched using the same fly ash, portland cement, and air- entraining agent as used in the test procedure. The values stated in SI units are to be regarded as the standard. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. 1.4. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations to use. Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure (Note 1). Note 1—The safety precautions given in the Manual of Aggregate and Concrete Testing, located in the related section of Volume 04.02 of the Annual Book of ASTM Standards, are recommended. The text of these standard reference notes provides explanatory material. These notes (excluding 1.5. those in tables and figures) shall not be considered as requirements of the standard. 2. REFERENCED DOCUMENTS ASTM Standards: 2.1. C125, Standard Terminology Relating to Concrete and Concrete Aggregates C311, Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete 3. TERMINOLOGY Definitions: 3.1. The terms used in this specification are defined in ASTM C125. 3.1.1.

B-3 4. SUMMARY OF TEST METHOD The foam index test is used to estimate the effect of a specific coal fly ash on the air entrainment 4.1. of concrete prepared with a specific portland cement and air-entraining admixture combination. The test is performed by visually noting the stability of the foam produced when the coal fly ash, portland cement and air-entraining admixture are combined with water and agitated. The test is designed to achieve a foam index value in 15 ± 3 min when conducted using an air-entraining admixture solution strength appropriate for the coal fly ash being tested. 5. SIGNIFICANCE AND USE The test provides an indication of possible changes in the amount of air-entraining admixture 5.1. required when using the same materials combination in concrete. The foam index is not an absolute measure of air-entraining admixture dosage for a concrete 5.2. mixture. The test result can be expressed in a number of different ways, depending upon the need of the 5.3. users, as presented in Section 9. 6. APPARATUS Pipette—capable of delivering a drop volume of 0.02 mL per drop. 6.1. Pipette should be calibrated prior to use in accordance with standard laboratory procedures. 6.1.1. 250 mL Wide-Mouth Nalgene®-Type Container with a Tight-Fitting Screw Top Lid. 6.2. Wrist-Action-Type Laboratory Shaker—capable of holding a 250 mL wide-mouth Nalgene-type 6.3. container. Wrist-action-type laboratory shaker should be adjustable in sample displacement and have timer 6.3.1. control capable of producing a 10 s and 30 s shake cycle. An example is shown in Figure 1. Figure 1. Example of a wrist-action-type laboratory shaker.

B-4 7. MATERIALS Coal Fly Ash—a grab sample, regular sample, or composite sample as described in C311, Sections 7.1. 6.1–6.3. Portland Cement—a 2 to 4 kg sample of the portland cement that is to be used, along with the coal 7.2. fly ash, in the final concrete mixture. Distilled Water—an adequate supply of distilled water. 7.3. Air-Entraining Admixture—an adequate supply of the air-entraining admixture to be used, along 7.4. with the coal fly ash, in the final concrete mixture. The air-entraining admixture should be prepared as standard aqueous solutions to be used for 7.4.1. testing. The concentration of the standard solutions can vary depending upon the coal fly ash and air-entraining admixture being tested. Recommended solution strengths are 2%, 6%, 10%, and 15% air-entraining admixture by volume. Solutions of any known concentration can be used. To ensure accuracy in mixing standard solutions, a minimum of 1 L of solution should be 7.4.2. prepared. Consult the air-entraining admixture manufacturer’s recommendations regarding the shelf life of 7.4.3. the prepared solutions. 8. PROCEDURE Determine Blank Sample Air-Entraining Admixture Requirements (Optional) 8.1. This part of the procedure establishes the air-entraining admixture needed to achieve a stable foam 8.1.1. with cement only. Depending upon how the results of the foam index test are to be presented and used, this portion may be optional. 8.1.1.1 Determine the initial solution concentration to use for the test. For cement, the lowest concentration solution should suffice. 8.1.1.2 In a 250 mL wide-mouth Nalgene-type container with a tight-fitting cap, combine 25 mL distilled water and 10 g of portland cement and tightly seal the container. 8.1.1.3 Secure container in the wrist-action shaker and agitate the container for 30 s, displacing it vertically approximately 20 cm. 8.1.1.4 Open the cap on the container. 8.1.1.5 With the container still in the wrist-action shaker, pipette a single drop (0.02 mL) of air-entraining admixture solution and tightly reseal the container. 8.1.1.6 Agitate the container with the wrist-action shaker for 10 s, displacing it vertically approximately 20 cm. 8.1.1.7 With the container still in the wrist-action shaker, open the cap, leaving the container undisturbed, and observe the contents at the air-slurry interface for foam. 8.1.1.8 If no foam is present or the foam is stable for less than 15 s, repeat Steps 8.1.1.4–8.1.1.7 until a stable foam remains for 15 s. Note 2—A stable foam is defined as a continuous foam cover at the air/liquid interface.

B-5 8.1.1.9 If the stable foam is achieved within a total test time of 12 to 18 min, record the total number of drops of air-entraining admixture solution added to achieve a stable foam (ND cement), the solution concentration of the air-entraining admixture solution used (CS cement), and the total test time (t cement). 8.1.1.10 If the stable foam is achieved outside of 12 to 18 min, adjust the solution concentration as described in Figure 2 and proceed from Step 8.1.1.2. Determine Combined Portland Cement & Coal Fly Ash Air-Entraining Admixture Requirements 8.2. This part of the procedure establishes the air-entraining admixture needed to achieve a stable foam 8.2.1. with portland cement and coal fly ash combined. 8.2.1.1 Determine the initial solution concentration to use for the test. For blends of cement and coal fly ash, the choice will be based upon experience or available information [e.g., known loss on ignition (LOI)]. 8.2.1.2 In a 250 mL wide-mouth Nalgene-type container with a tight-fitting cap, combine 25 mL of distilled water, 8 g of portland cement, and 2 g of coal fly ash and tightly seal the container. 8.2.1.3 Secure the container in the wrist-action shaker and agitate the container for 30 s, displacing it vertically approximately 20 cm. 8.2.1.4 Open the cap on the container. 8.2.1.5 With the container still in the wrist-action shaker, pipette a single drop (0.02 mL) of air-entraining admixture solution and tightly reseal the container. 8.2.1.6 Agitate the container with the wrist-action shaker for 10 s, displacing it vertically approximately 20 cm. 8.2.1.7 With the container still in the wrist-action shaker, open the cap, leaving the container undisturbed, and observe the contents at the air-slurry interface for foam. 8.2.1.8 If no foam is present or the foam is stable for less than 15 s, repeat Steps 8.2.1.4–8.2.1.7 until a stable foam remains for 15 s. 8.2.1.9 If the stable foam is achieved within a total test time of 12 to 18 min, record the total number of drops of air-entraining admixture solution added to achieve a stable foam (ND ash), the solution concentration of the air-entraining admixture solution used (CS ash), and the total test time (t ash). 8.2.1.10 If the stable foam is achieved outside of 12 to 18 min, adjust the solution concentration as described in Figure 2 and proceed from Step 8.2.1.2.

B-6 Figure 2. Protocol for conducting the foam index test and establishing the optimum AEA solution concentration to achieve an endpoint in 15 ± 3 min.

B-7 9. CALCULATION The results of the foam index test can be expressed many different ways. Each of these may have 9.1. application depending upon the purposes of the test. Calculations are based on 10 g of cementitious material for all tests conducted. 9.1.1. Data collected will consist of: 9.1.2. ND cement = number of drops of air-entraining admixture solution added to cement-only sample CS cement = concentration of air-entraining admixture solution added to cement-only sample ND ash = number of drops of air-entraining admixture solution added to cement/coal fly ash sample CS ash = concentration of air-entraining admixture solution added to cement/coal fly ash sample Foam Index cement = ND cement 0.02 9.2. Foam Index ash = ND ash 0.02 9.3. Absolute Volume cement = ND cement 0.02 CS cement 9.4. Absolute Volume ash = ND ash 0.02 CS ash 9.5. Specific Foam Index cement = Absolute Volume cement 10,000 9.6. Specific Foam Index ash = Absolute Volume ash 10,000 9.7. Relative Foam Index = [(Absolute Volume ash) / (Absolute Volume cement)] * 100 9.8. Where: Foam Index = volume of diluted air-entraining admixture solution added in the test, mL Absolute Volume = volume of undiluted air-entraining admixture solution added in the test, mL Specific Foam Index = undiluted air-entraining admixture per 100 kg cementitious material, mL Relative Foam Index = ratio of air-entraining admixture needed for cementitious mixture containing coal fly ash and air-entraining admixture required for cement- only mixture, expressed as a percentage of air-entraining admixture required for cement-only mixture 10. REPORT Report the following information 10.1. Time and date of test Fly ash source tested Portland cement tested Air-entraining admixture tested Solution strength (both CS cement and CS ash as applicable) Total test time (both t cement and t ash as applicable) Results of equations in Steps 9.2–9.8 (as applicable)

B-8 11. PRECISION AND BIAS Precision—A precision statement for this test has not yet been established. 11.1. Bias—There is no accepted standard sample that can be used to establish bias. 11.2. 12. KEYWORDS Coal fly ash; air-entraining admixture; foam index. 12.1.

B-9 Proposed Modifications to ASTM D4607 for Determining the Iodine Number for Coal Fly Ash The following are proposed modifications to ASTM D4607, Standard Test Method for Determination of Iodine Number of Activated Carbon, necessary for the determination of the iodine number for coal fly ash. It is proposed to replace several sections in ASTM D4607 with new sections; the proposed new sections are shown below. In addition, an unnumbered new section titled Materials is proposed for insertion after Section 5 Apparatus. Subsequent sections would need to be renumbered. 3. Summary of Test Method 3.1. This test method is based upon a four-point adsorption isotherm (see Practices D3860). A standard iodine solution is treated with four different weights of coal fly ash under specified conditions. The fly ash treated solutions are filtered to separate the fly ash from the treated iodine solution (filtrate). Iodine remaining in the filtrate is measured by titration. The amount of iodine removed per gram of fly ash is determined for each fly ash dosage and the resulting data used to plot an adsorption isotherm. The amount of iodine adsorbed (in milligrams) per gram of fly ash at a residual iodine concentration of 0.01 N is reported as the coal fly ash iodine number. 3.2. Iodine concentration in the standard solution affects the capacity of carbon for iodine adsorption. Therefore, the normality of the standard iodine solution must be maintained at a constant value (0.025 ± 0.001 N) for all iodine number measurements. 3.3. The apparatus required consists of various laboratory glassware used to prepare solutions and contact coal fly ash with the standard iodine solution. Filtration and titration equipment are also required. 4. Significance and Use 4.1. Coal fly ash is composed of inorganic and organic phases with the organic phases occurring as unburned carbon resulting from the coal combustion process. Carbon may also be present when used for flue gas treatment to meet emission criteria. The carbon is assumed to be the sole adsorbent of iodine. 4.2. The iodine number is a relative indicator of porosity in activated carbon. It does not necessarily provide a measure of the carbon’s ability to absorb other species. Iodine number may be used as an approximation of surface area for some types of activated carbons (see Test Method C819). However, it must be realized that any relationship between surface area and iodine number cannot be generalized. It varies with many factors relating to the source of the carbon and the conditions under which it is produced in the combustion process.

B-10 4.3. The presence of adsorbed volatiles, sulfur, and water extractables may affect the measured iodine number of an activated carbon in coal fly ash. This procedure includes a pre-treatment step to remove sulfur known to exist in coal fly ash. 5. Apparatus 5.1. Analytical Balance—accuracy ± 0.0001 g. 5.2. Buret—25 mL capacity precision buret with stand. 5.3. Flasks—Erlenmeyer 250 mL capacity with a ground glass stopper or rubber stopper. 5.4. Flask—Erlenmeyer wide-mouthed, 250 mL capacity. 5.5. Vacuum Flask—1 L. 5.6. Aspirator or Other Source of Vacuum. 5.7. Beakers—assorted sizes. 5.8. Bottles—1 L minimum, amber, for storage of iodine and thiosulfate solutions. 5.9. Glass-Stoppered Bottles—1 L minimum, for storage of potassium iodate. 5.10. Funnels—100 mm top inside diameter. 5.11. Buchner Funnel—90 mm diameter. 5.12. Filter Paper—Grade 1, 11 m, 90 mm diameter, cellulose, Whatman qualitative filter paper, or equivalent. 5.13. Pipettes—volumetric type, 5.0, 10.0, and 25.0 mL capacity. 5.14. Volumetric Flasks—1 L. 5.15. Graduated Cylinders—100 mL. 5.16. Eyedropper. 5.17. Mortar and Pestle. 5.18. 200 Mesh Sieve. 5.19. Magnetic Stirrer. 5.20. Hot Plate with Magnetic Stirrer. 5.21. Drying Oven. X. Materials X.1. Coal Fly Ash—a grab sample, regular sample, or composite sample as described in ASTM C311, Sections 6.1–6.3. 10. Procedure 10.1. Take a 500.0 mL volume of the solution prepared in Step 9.1 and perform a 3:1 dilution with three parts distilled water to produce a 0.025 N sodium thiosulfate solution. 10.2. Take a 500.0 mL volume of the solution prepared in Step 9.2 and perform a 3:1 dilution with three parts distilled water to produce a 0.025 N iodine solution. 10.3. Obtain a 300 to 400 g sample of the coal fly ash to be tested (See added section on Materials). This sample is boiled for 5 min in a solution of 5% weight HCl. The total

B-11 mass of boiling solution should be at least four times that of the coal fly ash to be treated to ensure the availability of enough HCl to remove all sulfur and acidify the fly ash. The coal fly ash is then filtered using Grade 1, 90 mm diameter, cellulose, qualitative filter paper, or any equivalent filter paper, and dried at 103°C to a constant weight. 10.3.1. After drying, it may be necessary to break up the treated coal fly ash using a mortar and pestle such that all of the material passes through a 200 mesh sieve. Note 1: Due to the relatively low adsorption capacity of coal fly ash, large masses of coal fly ash are required to adsorb enough iodine to cause an accurately measurable reduction in the iodine solution concentration. 10.4. From the treated sample (Step 10.3) weigh 10, 20, 40, and 80 g of treated coal fly ash. These will be referred to as samples a, b, c, and d, respectively. Record their respective weights to 0.001 g as MFA(a), MFA(b), MFA(c), and MFA(d). 10.4.1. The quantities specified in Step 10.4 are sufficient for most types of coal fly ash. In the case of very high carbon coal fly ash, or high activity coal fly ash, smaller quantities of treated sample may be required. This is readily determined by observing the solution color in Step 10.6 as the coal fly ash is added. If adding the coal fly ash causes the solution to become clear, the quantity added is in excess of the amount required (i.e., it has adsorbed all available iodine from solution). 10.4.2. It is recommended that Steps 10.6–10.9 be conducted first with the 10 g sample, then the 20 g sample, etc. If a level of treated sample addition results in the situation described in Step 10.4.1, use treated sample weights that reduce by a factor of 2 from the lowest successful test. Example: If 10 g and 20 g are both adequate, but 40 g is in excess, then use 5 g and 2.5 g samples to complete the series of four tests. 10.4.3. It is recommended that four different weights of treated coal fly ash be reacted with iodine solution, resulting in four data points to establish the adsorption isotherm. 10.5. Prepare vacuum flask, Buchner funnel, and Grade 1 90 mm diameter filter paper. 10.6. Starting with treated coal fly ash sample a, place the treated coal fly ash sample in a 250 mL Erlenmeyer flask and add 100.0 mL of the 0.025 N iodine solution (Step 10.2). Close the flask to minimize iodine volatilization. Place the flask on a stirring plate and stir the mixture for 5 min. 10.7. Quickly filter the mixture from Step 10.6. 10.8. Transfer the filtrate to a graduated cylinder and determine the volume of filtrate. Record this as the respective final iodine solution volume (Vf). 10.9. From the captured filtrate (Step 10.8), use the first 10 to 20 mL to rinse a pipette. Discard the rinse portions. Use clean beakers to collect the remaining filtrate. Mix each filtrate by swirling the beaker and then pipette 25.0 mL of each filtrate into a clean 250 mL Erlenmeyer flask. Titrate the filtrate with the standardized 0.025 N

B-12 sodium thiosulfate solution (Step 10.1) until the solution is a pale yellow. Add approximately 0.5 mL of the starch indicator solution (Step 8.5) with an eye dropper and continue the titration with sodium thiosulfate until one drop produces a colorless solution. Record this as the respective volume of sodium thiosulfate used (VT). 10.10. Repeat Steps 10.5–10.9 for the remaining three samples (e.g. 20, 40, and 80 g samples from Step 10.4) 11. Calculation 11.1 For each treated coal fly ash sample a–d (i.e. MFA(a), MFA(b), MFA(c), MFA(d)), determine a corresponding solid phase iodine concentration (i.e., qFA(a), qFA(b), qFA(c), qFA(d)) using the equation: FAq = 0 0C  – fV fC  FAM (3) where: qFA = solid phase iodine concentration (mg iodine / g fly ash ) V0 = initial iodine solution volume (L) C0 = initial iodine solution concentration (mg / L) Vf = final iodine solution volume (L) Cf = final iodine solution concentration (mg / L) MFA = mass of fly ash (g) Determine C0 as: 0C = 2N 126930 (4) Determine Cf as: fC = TV 0C25 (5) 11.2 For each solid phase iodine concentration (i.e., qFA(a), qFA(b), qFA(c), qFA(d)), determine a corresponding solution normality (i.e., NFA(a), NFA(b), NFA(c), NFA(d)) using the equation: FAN = TV 2N25 (6) 11.3 Using a log-log plotting method, plot the four respective values of NFA (x-axis) versus qFA (y-axis). Fit a straight line to the four data points in the plot. An example is shown in Figure 1. 11.4 Using the plot produced in Step 11.3, enter the plot at a normality value (x-axis) of 0.01 and read the corresponding y-axis value (q). V

B-13 Figure 1. Example of iodine adsorption isotherm for coal fly ash. 12. Report 12.1. The reports should include the following: 12.1.1. Time and date of test 12.1.2. Fly ash source tested 12.1.3. Iodine number determined

B-14 Proposed Method of Test for Determination of Air-Entraining Admixture Adsorption by Coal Fly Ash 1. SCOPE This test method covers the determination of the quantity of air-entraining admixture (AEA) 1.1. adsorbed by coal fly ash from an aqueous solution. The result is expressed as the volume of air- entraining admixture adsorbed per unit mass of coal fly ash (mL AEA/g fly ash). The quantity of air-entraining admixture adsorbed is a function of the solution air-entraining admixture concentration. This standard does not purport to address all of the safety concerns, if any, associated with its use. 1.2. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations to use. 2. REFERENCED DOCUMENTS ASTM Standards: 2.1. D2652, Standard Terminology Relating to Activated Carbon C311, Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete D3860, Standard Practice for Determination of Adsorptive Capacity of Activated Carbon by Aqueous Phase Isotherm Technique 3. TERMINOLOGY The terms used in this specification relative to activated carbon are defined in ASTM D2652. 3.1. 4. SUMMARY OF TEST METHOD The determination is based upon a three-point direct adsorption isotherm similar to that described 4.1. in ASTM D3860. The isotherm provides a direct measurement of the amount of air-entraining admixture adsorbed by a coal fly ash. A direct adsorption isotherm is determined by equilibrating mixtures of cement, fly ash, and air-4.2. entraining admixture solutions to determine the reduction in air-entraining admixture aqueous phase concentration due to adsorption by coal fly ash. Portland cement is added to the system to account for the air-entraining admixture that is 4.3. chemisorbed by the portland cement in a concrete mixture. A system that contains only cement and air-entraining admixture is utilized as a blank to determine the aqueous phase concentration of air-entraining admixture after chemisorption takes place. This aqueous phase concentration is considered to be the initial aqueous phase concentration. The reduction in this concentration resulting from the addition of coal fly ash to the system is used to determine the mass of air- entraining admixture adsorbed by fly ash. The coal fly ash adsorption capacity is determined by dividing the mass of air-entraining 4.4. admixture adsorbed from the solution by the mass of coal fly ash utilized in determining the isotherm point. Multiple isotherm points are obtained by varying the concentration of the air-entraining admixture solution. The isotherm points are analyzed using the Freundlich isotherm model that

B-15 describes the correlation between solid phase (coal fly ash) capacity and the equilibrium air- entraining admixture aqueous phase concentration. A test for chemical oxygen demand (mg COD/L) is used to determine the concentration of air-4.5. entraining admixture in solution. The concentration of air-entraining admixture in the solution affects the capacity of a coal fly ash 4.6. for air-entraining admixture adsorption. The required apparatus consists of various laboratory glassware used to prepare solutions and 4.7. contact coal fly ash with the air-entraining admixture solutions. Filtration equipment is also required. A spectrophotometric method is employed to determine COD. 5. SIGNIFICANCE AND USE The partitioning of an air-entraining admixture among the various solid phases in a concrete 5.1. mixture is identified and quantified using this direct adsorption isotherm test method. Direct adsorption isotherms quantify the interaction between coal fly ash and an air-entraining admixture. An isotherm provides a quantitative measurement of the amount of air-entraining admixture 5.2. adsorbed by a coal fly ash, which can be used to predict and adjust the dosage of air-entraining admixture, relative to a baseline dosage used for a concrete mixture with no coal fly ash, to compensate for the air-entraining admixture adsorbed when a coal fly ash is added or substituted into the concrete mixture. 6. APPARATUS Analytical Balance—accuracy ± 0.01 g. 6.1. Flasks—Erlenmeyer 250 mL capacity with a ground-glass stopper or rubber stopper. 6.2. Volumetric Flasks—200 mL and 1 L. 6.3. Vacuum Flask—1 L. 6.4. Aspirator or Other Source of Vacuum. 6.5. Buchner Funnel—90 mm top inside diameter. 6.6. Filter Paper—Grade 1, 11 µm, 90 mm diameter, cellulose, Whatman qualitative filter paper, or 6.7. equivalent. Pipettes—volumetric type, 2.0 mL capacity. 6.8. Graduated Cylinders—100 and 200 mL. 6.9. Magnetic Stirrer. 6.10. Drying Oven. 6.11. COD Determination Test Kit— HACH Method 8000, high-range COD or equivalent. 6.12. 7. REAGENTS Water—distilled or reagent water. 7.1. 8. MATERIALS Coal Fly Ash—a grab sample, regular sample, or composite sample as described in C311, Sections 8.1. 6.1–6.3. Portland Cement—Select the specific cement to be used with the coal fly ash (Step 8.1) and air-8.2. entraining admixture (Step 8.3) in any concrete mixture. If the specific portland cement is unavailable, a portland cement of the same type (i.e., AASHTO M 85 type) and similar

B-16 composition and Blaine fineness may be substituted, but the performance of the air-entraining admixture predicted by this test method may vary. Air-Entraining Admixture—Select the specific air-entraining admixture to be used with the coal 8.3. fly ash (Step 8.1) and portland cement (Step 8.2) in any concrete mixture. 9. MEASUREMENT OF CHEMICAL OXYGEN DEMAND The concentration of air-entraining admixture in solution is determined by measuring the solution 9.1. chemical oxygen demand (COD), expressed in mg COD/L. Standard procedures for measuring COD are given in Standard Methods for the Examination of 9.2. Water and Wastewater1. Two specific methods are described: 5220C closed reflux titrimetric method and 5220D closed reflux colorimetric method. Either method is acceptable. Method 5220D closed reflux colorimetric method is recommended. Kits are commercially available to facilitate performing the 5220D closed reflux colorimetric 9.3. method, as described in Section 6. 10. PREPARATION OF SOLUTIONS There are no specific solution strengths required to perform the test. To accurately determine 10.1. COD, it is recommended that three solution strengths (i.e., solutions i, ii, and iii) be selected that result in COD falling in the range of 300 to 1300 mg COD/L after aliquots of the solutions have equilibrated with 20 g of portland cement. These will be used to determine isotherm points i, ii, and iii, respectively. Note 1—In most cases AEA solutions having concentrations of 5, 10, and 20 mL/L will produce CODBK measurement (Step 10.3.11) between 100 and 1300 mg COD /L after equilibrating with 20 g of the portland cement. Note 2—If laboratory facilities permit, all three solutions or coal fly ash/portland cement/solution combinations can be reacted simultaneously. The procedure described herein assumes each solution or each coal fly ash/portland cement/solution combination will be reacted synchronously rather than simultaneously. The relationship between air-entraining admixture concentration and COD must be determined 10.2. separately for each different air-entraining admixture type to be evaluated. Determine the COD/Air-Entraining Admixture Solution Concentrations: 10.3. Assemble and prepare the vacuum filter apparatus. 10.3.1. Measure 5 mL of air-entraining admixture using a graduated cylinder. 10.3.2. Add the air-entraining admixture to a 1 L volumetric flask and dilute the air-entraining admixture 10.3.3. with distilled water to a total solution volume of 1 L. Record the initial solution concentration (C0i) in mL AEA/L. 10.3.4. Measure 200 mL of the air-entraining admixture solution. 10.3.5. Weigh 20 g of portland cement and record to nearest 0.01g (MPCi). 10.3.6. Combine the 200 mL of air-entraining admixture solution with 20 g of portland cement in a 10.3.7. 250 mL Erlenmeyer flask. Add a magnetic stirring bar and stopper the flask. Stir for 60 ± 2 min using a stir speed sufficient to keep the solids in suspension. If necessary, use a 10.3.8. glass rod to initiate stirring. Remove the solution and portland cement from the stirrer and filter. If vacuum is lost as a result of 10.3.9. cracks forming in the filter cake, use a spatula to close the cracks. Filter until filtrate is produced at a rate of approximately 1 drop every 10 s.

B-17 Transfer the filtrate to a graduated cylinder and determine the volume of filtrate in liters (L). 10.3.10. Record this as the respective final solution volume (VBKi). Determine the COD of the final solution and record this as CODBKi. 10.3.11. If the CODBKi is less than 100 mg COD/L or greater than 1300 mg COD/L, estimate by ratio the 10.3.12. required air-entraining admixture volume to achieve a CODBKi of approximately 800 mg COD/L and repeat Steps 10.3.3–10.3.11. Based upon the results of Step 10.3.11, estimate by ratio the air-entraining admixture volume 10.3.13. required to prepare solutions ii and iii with final solution concentrations (i.e., solution concentration after contact with the portland cement) such that together the three prepared solutions adequately cover the range of 100 to 1300 mg COD/L. Repeat Steps 10.3.3–10.3.10 to prepare solutions ii and iii and record MPCii, MPCiii, C0ii, C0iii, COD0ii, COD0iii, VFii, VFiii, CODBKii, and CODBKiii. 11. PROCEDURE Obtain a 300 to 400 g sample of the coal fly ash to be tested (Step 8.1). Dry this sample to 11.1. constant weight at a temperature of 110° ± 2° C. Obtain a 300 to 400 g sample of the portland cement to be tested (Step 8.2). 11.2. Assemble and prepare the vacuum filter apparatus. 11.3. Determine the COD Contribution from the Fly Ash: 11.4. Measure 80 g of the coal fly ash and record this weight to 0.01 g (MFA*). 11.4.1. Measure 200 mL of distilled water. 11.4.2. Combine the 80 g of coal fly ash and 200 mL of distilled water in a 250 mL Erlenmeyer flask. 11.4.3. Add a magnetic stirring bar and stopper the flask. Stir for 60 ± 2 min using a stir speed sufficient to keep the solids in suspension. If necessary, use a 11.4.4. glass rod to initiate stirring. Remove the slurry from the stirrer and filter. If vacuum is lost as a result of cracks forming in the 11.4.5. filter cake, use a spatula to close the cracks. Filter until filtrate is produced at a rate of approximately 1 drop every 10 s. Transfer the filtrate to a graduated cylinder and determine the volume of filtrate in liters (L). 11.4.6. Record this as the respective final solution volume (VFA*) Determine the COD of the final solution and record this as CODFA*. 11.4.7. Determine the COD Contribution from the Portland Cement: 11.5. Measure 80 g of the portland cement and record this weight to 0.01 g (MPC*). 11.5.1. Measure 200 mL of distilled water. 11.5.2. Combine the 80 g of portland cement and 200 mL of distilled water in a 250 mL Erlenmeyer flask. 11.5.3. Add a magnetic stirring bar and stopper the flask. Stir for 60 ± 2 min using a stir speed sufficient to keep the solids in suspension. If necessary, use a 11.5.4. glass rod to initiate stirring. Remove the slurry from the stirrer and filter. If vacuum is lost as a result of cracks forming in the 11.5.5. filter cake, use a spatula to close the cracks. Filter until filtrate is produced at a rate of approximately 1 drop every 10 s. Transfer the filtrate to a graduated cylinder and determine the volume of filtrate in liters (L). 11.5.6. Record this as the respective final solution volume (VPC*)

B-18 Determine the COD of the final solution and record this as CODPC*. 11.5.7. Determine the COD of the Isotherm Data Points: 11.6. Measure 200 mL of air-entraining admixture solution i 11.6.1. Measure 40 g of the coal fly ash to be tested. Record the weight to 0.01 g (MFAi). 11.6.2. Measure 20 g of the portland cement to be tested. Record the weight to 0.01 g (MPCi). 11.6.3. Combine the 200 mL of air-entraining admixture solution with the 40 g of coal fly ash (Step 11.6.4. 11.6.2) and 20 g of portland cement in a 250 mL Erlenmeyer flask. Add magnetic stirring bar and stopper the flask. Stir for 60 ± 2 min using a stir speed sufficient to keep the solids in suspension. 11.6.5. Remove the slurry from the stirrer and filter. If vacuum is lost as a result of cracks forming in the 11.6.6. filter cake, use a spatula to close the cracks. Filter until filtrate is produced at a rate of approximately 1 drop every 10 s. Transfer the filtrate to a graduated cylinder and determine the volume of filtrate in liters (L). 11.6.7. Record this as the respective final solution volume (VFCi). Determine the COD of the final solution and record this as CODFCi. 11.6.8. Repeat Steps 11.6.1–11.6.8 for solutions ii and iii. 11.6.9. 12. CALCULATION Determine the Coal Fly Ash Capacity (q) at Each Solution Strength: 12.1. Capacity for solutions (mL air entraining admixture / g coal fly ash) (repeat for solutions ii and iii): (1) Determine Final Air-Entraining Admixture Concentration in Water 12.2. (2) Determine the final air-entraining admixture concentration in water for solutions ii and iii, substituting in the associated values for those determinations. Plot Solution Concentration versus Capacity: 12.3. Plot the results using a log-log scale. Plot the solution concentration (i.e., C0i, C0ii, C0iii) on the x- axis and capacity (i.e., qi, qii, qiii) on the y-axis. Fit a power line to the data, the equation for which can be used to determine the volume of air- entraining admixture adsorbed per gram of coal fly ash, as a function of the air-entraining admixture concentration. An example plot is shown in Figure 1.

B-19 Figure 1. Example of direct adsorption isotherm for coal fly ash. To use the graph, calculate the air-entraining admixture dosage for a concrete mixture design in 12.4. terms of percentage of air-entraining admixture by volume. Enter the graph on the x-axis at the determined percentage of air-entraining admixture by volume. Intercept the isotherm line and read off the corresponding fly ash capacity on the y-axis. The capacity determined is the volume of air- entraining admixture that will be adsorbed per gram of fly ash. An example calculation is shown below: 12.5. Concrete Mix Design Parameters: Quantity Item Customary Units Converted Units Water 290 lb 34.8 gal Air-Entraining Admixture 11.5 fl oz 0.09 gal Assume 100 lb (45.4 kg) of fly ash is substituted for 100 lb of portland cement. Volume % Air-Entraining Admixture = 0.09 gal Air-Entraining Admixture 34.8 gal water × 100 = 0.26 volume % From Figure 1, fly ash capacity = 0.05 mL air-entraining admixture per gram coal fly ash 0.05 mL air-entraining admixture g coal fly ash 45.4 kg coal fly ash 1000 g 1 kg =× × 2270 mL air-entraining admixture 2270 mL air-entraining admixture 1 fl oz 29.57 mL =× 76.8 fl oz In this example, it is estimated 100 lb of coal fly ash has the capacity of 76.8 fl oz of air-entraining admixture. y = 0.0658x0.2027 0.01 0.1 0.01 0.1 1 Fl y As h Ca pa ci ty (m L A EA /g as h) AEA Concentration (% vol.) 0.05

B-20 13. REPORT Report the following information 13.1. Time and date of test Fly ash source tested Cement source tested Air-entraining admixture tested Coal fly ash capacity plot and power fit equation for the adsorption isotherm 14. PRECISION AND BIAS Precision—To be determined. 14.1. Bias—There is no accepted standard sample that can be used to establish bias. 14.2. 15. KEYWORDS Coal fly ash; air-entraining admixture; direct adsorption isotherm. 15.1. 1 Eaton, A. D., L. S. Clesceri, E. W. Rice, A. E. Greenberg, and M. H. Franson, eds. Standard Methods for the Examination of Water and Wastewater, 21st ed., Port City Press, Baltimore, Md., 2005, pp. 4-58 to 4-60. ISBN 0-87553-047-8.