Topic 5 - Preparation and Curing of Concrete Specimen.pdf

Construction Materials and Testing CE312 by: Engr. Vera Karla Caingles Preparation and Curing of Concrete Test Specimen by: Engr. Vera Karla Caingles  Standard...

Construction Materials and Testing CE312 by: Engr. Vera Karla Caingles Preparation and Curing of Concrete Test Specimen by: Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory Standard Practice for Making by: Engr. Vera Karla Caingles and Curing Concrete Test Specimens in the Field by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test SCOPE Specimens in the Laboratory 1. This practice covers procedures for making and curing test specimens of concrete in the laboratory under accurate control of materials and test conditions using concrete that can be consolidated by rodding or vibration. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test SCOPE Specimens in the Laboratory 2. The values stated in either inch- pound units or SI units shall be regarded separately as standard. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of each other. Combining values from the two systems may result in nonconformance. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test SCOPE Specimens in the Laboratory 3. 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. (Warning: Fresh hydraulic cementitious mixtures by: Engr. Vera Karla Caingles are caustic and may cause chemical by: burns to exposed skin and tissue upon Engr. Vera Karla Caingles prolonged exposure).  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Laboratory  This practice provides standardized requirements for preparation of materials, mixing concrete, and making and curing concrete test specimens under laboratory conditions.  If specimen preparation is controlled as stipulated herein, the specimens may be used to develop information for the following purposes: Mixture proportioning for project concrete, Evaluation of different mixtures and materials, Correlation with nondestructive tests, and by: Providing specimens for research purposes Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Laboratory Mixture proportioning for project concrete, by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Laboratory Evaluation of different mixtures and materials, by: Engr. Vera Karla Caingles and Engr. Roxanne C. Galdo by: Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Laboratory Correlation with nondestructive tests, and by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Laboratory Providing specimens for research purposes by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Molds Molds for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron, or other nonabsorbent material, nonreactive with concrete containing portland or other hydraulic cements. Molds shall conform to the dimensions and tolerances specified in the method for which the specimens are required. by: Engr. Vera Karla Caingles Molds shall hold their dimensions and shape under all conditions of use. by: Watertightness of molds during use shall be judged by their ability to hold water poured Engr. Vera Karla Caingles into them.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Molds by: Engr. Vera Karla Caingles by: Beam or Prism Mold Engr. Vera Karla Caingles Cylinder Mold  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Tamping Rods Two sizes are specified in ASTM methods. Each shall be a round, straight steel rod with at least the tamping end rounded to a hemispherical tip of the same diameter as the rod. Both ends may be rounded, if preferred. by: Engr. Vera Karla Caingles by: Larger Rod Smaller Rod Engr. Vera Karla Caingles 5Ú8 in. [16 mm] in diameter and 3Ú8 in. [10 mm] in diameter and Approximately 24 in. [600 mm] long. Approximately 12 in. [300 mm] long.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Mallets A mallet with a rubber or rawhide head weighing 1.25 + 0.50 lb [0.6 + 0.20 kg] shall be used. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Vibrators by: Engr. Vera Karla Caingles Internal Vibrators External Vibrators The vibrator frequency shall be at least 7000 vibrations The two types of external vibrators by: per minute [115 Hz] while the vibrator is operating in the permitted are either table or plank. The external vibrator Engr. Vera Karla Caingles concrete. The diameter of a round vibrator shall be no frequency shall be 3600 vibrations per minute [60 Hz] or more than one fourth the diameter of the cylinder higher. mold or one fourth the width of the beam or prism mold.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Small Tools Tools and items such as shovels, pails, trowels, wood float, blunted trowels, straightedge, feeler gage, scoops, rulers, rubber gloves, and metal mixing bowls shall be provided. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Slump Apparatus by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Sampling and Mixing Pan The pan shall be flat bottom and of heavy-gage metal, watertight, of convenient depth, and of sufficient capacity to allow easy mixing by shovel or trowel of the entire batch; or, if mixing is by machine, to receive the by: Engr. Vera Karla Caingles entire batch on discharge of the mixer and allow remixing in the pan by trowel by: or shovel. Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Wet-Sieving Equipment by: Engr. Vera Karla Caingles by: If wet-sieving is required, the Engr. Vera Karla Caingles equipment shall conform to the requirements of Practice C 172.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Air Content Apparatus The apparatus for measuring air content shall conform to the requirements of either Test Methods C 231 or C 173. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Scales Scales for determining the mass of batches of materials and concrete shall be accurate within 0.3 % of the test load at any point within the range of by: Engr. Vera Karla Caingles use. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Temperature Measuring Device The temperature measuring device shall conform to the requirements of Test Method C 1064. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Laboratory Concrete Mixer A power-driven concrete mixer shall be a revolving drum, tilting mixer, or suitable revolving pan or revolving- paddle mixer capable of thoroughly mixing batches of the prescribed sizes at the required slump. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Preparation of Materials Specimens in the Laboratory Temperature Before mixing the concrete, bring the concrete materials to room temperature in the range from 68 to 86 °F [20 to 30 °C], except when the temperature of the concrete is stipulated. When a concrete temperature is stipulated, the method proposed to obtain the by: Engr. Vera Karla Caingles concrete temperature needs approval of the stipulator. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Preparation of Materials Specimens in the Laboratory Cement Store the cement in a dry place, in moisture proof containers, preferably made of metal. The cement shall be thoroughly mixed to provide a uniform supply throughout the tests. It shall be passed through a 850-μm [No. 200] or finer sieve to remove all lumps, remixed on a by: Engr. Vera Karla Caingles plastic sheet, and returned to sample containers. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Preparation of Materials Specimens in the Laboratory Aggregates Determine the specific gravity and absorption of aggregates in accordance with either Test Methods C 127 or C 128. The moisture content of the aggregates may be determined in accordance with Test Methods C 70 and C 566. Surface moisture in fine aggregate may be determined in accordance with Test Methods C 70 and C 566, making due allowance for the amount of water absorbed. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Preparation of Materials Specimens in the Laboratory Aggregates Aggregates, fine or coarse, may be brought to and maintained in a saturated surface-dry condition until batched for use. This method is used primarily to prepare material for batches not exceeding 1Ú4 ft3 [0.007 m3] in volume. Care must be taken to prevent drying during weighing and use. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Preparation of Materials Specimens in the Laboratory Lightweight Aggregates Lightweight aggregates, air- cooled slag, and certain highly porous or vesicular natural aggregate may be so absorptive as to be difficult to treat as described. The moisture content of lightweight aggregate at the time of mixing may have important effects on properties of freshly mixed and by: Engr. Vera Karla Caingles hardened concretes such as slump loss, compressive strength, and by: resistance to freezing and thawing. Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Preparation of Materials Specimens in the Laboratory Admixtures Powdered admixtures that are entirely or largely insoluble, that do not contain hygroscopic salts and are to be added in small quantities, should be mixed with a portion of the cement before introduction into the batch in the mixer so as to ensure thorough distribution throughout the concrete. Essentially insoluble materials which are used in amounts exceeding 10 % by mass of cement, such as pozzolans, should be handled and added to the batch in the same manner as cement. Powdered admixtures which by: Engr. Vera Karla Caingles are largely insoluble but contain hygroscopic salts may cause balling of cement and should be mixed with the sand. Water-soluble and liquid admixtures should be by: added to the mixer in solution in the mixing water. The Engr. Vera Karla Caingles quantity of such solution used shall be included in the calculation of the water content of the concrete.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Mixing Concrete A General Mix concrete in a suitable mixer or by hand in batches of such size as to leave about 10 % excess after molding the test specimens. Hand-mixing procedures are not applicable to air- entrained concrete or concrete with no measurable slump. Hand mixing should be limited to batches of 1Ú4 ft3 [0.007 m3] volume or less. Machine Mixing 1. Prior to starting rotation of the mixer add the coarse aggregate, some of the mixing water, and the solution of admixture. 2. When feasible, disperse the admixture in the mixing water before addition. 3. Start the mixer, then add the fine aggregate, cement, and water with the mixer running. If it is impractical for a particular mixer or for a particular test to add the fine aggregate, cement, and water while the mixer is running, these components by: Engr. Vera Karla Caingles may be added to the stopped mixer after permitting it to turn a few revolutions following charging with coarse aggregate and some of the water. 4. Mix the concrete, after all ingredients are in the mixer, for 3 min followed by a 3-min rest, followed by a 2-min final by: mixing. Engr. Vera Karla Caingles 5. Cover the open end or top of the mixer to prevent evaporation during the rest period. Take precautions to compensate for mortar retained by the mixer so that the discharged batch, as used, will be correctly proportioned. 6. To eliminate segregation, deposit machine-mixed concrete in the clean, damp mixing pan and remix by shovel or trowel until it appears to be uniform.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Mixing Concrete A Hand Mixing 1. Mix the batch in a watertight, clean damp, metal pan or bowl, with a bricklayer’s blunted trowel, using the following procedure when aggregates have been prepared. 2. Mix the cement, powdered insoluble admixture, if used, and fine aggregate without addition of water until they are thoroughly blended. 3. Add the coarse aggregate and mix the entire batch without addition of water until the coarse aggregate is uniformly distributed throughout the batch. 4. Add water, and the admixture solution if used, and mix the mass until the concrete is homogeneous in appearance and has the desired consistency. 5. If prolonged mixing is necessary because of the addition of water in increments while adjusting the consistency, discard the batch and make a new batch in which the mixing is not interrupted to make trial by: Engr. Vera Karla Caingles consistency tests. by: Mixed Concrete Engr. Vera Karla Caingles Select the portions of the batch of mixed concrete to be used in tests for molding specimens so as to be representative of the actual proportions and condition of the concrete. When the concrete is not being remixed or sampled cover it to prevent evaporation.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Slump, Air Content, Yield, and Temperature B Slump Measure the slump of each batch of concrete immediately after mixing in accordance with Test Method C 143/C 143M. Air Content Determine the air content, when required, in accordance with either Test Methods C 173 or C 231. Test Method C 231 should not be used with concretes made with lightweight aggregates, air-cooled blast-furnace slag, or aggregates of high porosity. Discard the concrete used for the determination of air content. Yield by: Engr. Vera Karla Caingles Determine the yield of each batch of concrete, if required, in accordance with Test Method C 138. Concrete used for slump and yield tests may be returned to the mixing pan and remixed into the batch. by:Engr. Vera Karla Caingles Temperature Determine the temperature of each batch of concrete in accordance with Test Method C 1064.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Making Specimens C Place of Molding Mold specimens as near as practicable to the place where they are to be stored during the first 24 h. If it is not practicable to mold the specimens where they will be stored, move them to the place of storage immediately after being struck off. Place molds on a rigid surface free from vibration and other disturbances. Avoid jarring, striking, tilting, or scarring of the surface of the specimens when moving the specimens to the storage place. Placing Place the concrete in the molds using a scoop, blunted trowel, or shovel. Select each scoopful, trowelful, or shovelful of concrete from the mixing pan to ensure that it is representative of the batch. It may be necessary to by: Engr. Vera Karla Caingles remix the concrete in the mixing pan with a shovel or trowel to prevent segregation during the molding of specimens. Move the scoop or trowel around the top edge of the mold as the concrete is discharged in order to by: ensure a symmetrical distribution of the concrete and to minimize segregation of coarse aggregate within the Engr. Vera Karla Caingles mold. Further distribute the concrete by use of a tamping rod prior to the start of consolidation. In placing the final layer the operator shall attempt to add an amount of concrete that will exactly fill the mold after compaction. Do not add nonrepresentative samples of concrete to an underfilled mold.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Making Specimens C Number of Layers by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Consolidation D Methods of Consolidation Preparation of satisfactory specimens requires different methods of consolidation. The methods of consolidation are rodding, and internal or external vibration. Base the selection of the method on the slump, unless the method is stated in the specifications under which the work is being performed. Rod or vibrate concrete with slump greater than or equal to 1 in. [25 mm]. Vibrate concrete with slump less than 1 in. Do not use internal vibration for cylinders with a diameter less than 4 in. [100 mm], and for beams or prisms with breath or depth less than 4 in. Rodding Place the concrete in the mold, in the required number of layers of approximately equal volume. Rod each by: Engr. Vera Karla Caingles layer with the rounded end of the rod using the number of strokes and size of rod. Rod the bottom layer throughout its depth. Distribute the strokes uniformly over the cross section of the mold and for each upper layer by: allow the rod to penetrate through the layer being rodded and into the layer below approximately 1 in. [25 Engr. Vera Karla Caingles mm]. After each layer is rodded, tap the outsides of the mold lightly 10 to 15 times with the mallet to close any holes left by rodding and to release any large air bubbles that may have been trapped. Use an open hand to tap light-gage single-use molds which are susceptible to damage if tapped with a mallet. After tapping, spade the concrete along the sides and ends of beam and prism molds with a trowel or other suitable tool.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Consolidation D Vibration Maintain a uniform duration of vibration for the particular kind of concrete, vibrator, and specimen mold involved. The duration of vibration required will depend upon the workability of the concrete and the effectiveness of the vibrator. Usually sufficient vibration has been applied as soon as the surface of the concrete becomes relatively smooth and large air bubbles cease to break through the top surface. Continue vibration only long enough to achieve proper consolidation of the concrete. Overvibration may cause segregation. Fill the molds and vibrate in the required number of approximately equal layers. Place all the concrete for each layer in the mold before starting vibration of that layer. When placing the final layer, avoid overfilling by more than 1Ú4 in. [6 mm]. When the finish is applied after vibration, add only enough concrete with a trowel to overfill the mold about 1Ú8 in. [3 mm], work it into the surface and then strike it off. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Consolidation D Internal Vibration In compacting the specimen insert the vibrator slowly and do not allow the vibrator to rest on or touch the bottom or sides of the mold or strike embedded items such as strain meters. Slowly withdraw the vibrator so that no large air pockets are left in the specimen. Cylinders When more than one insertion per layer is required, distribute the insertions uniformly within each layer. Allow the vibrator to penetrate into the layer below approximately 1 in. [25 mm]. After each layer is vibrated, tap the outside of the mold at least 10 times with the mallet to close the holes that remain and to release entrapped air voids. Use an open hand to tap cardboard or single-use metal molds that are susceptible to damage if tapped with a mallet. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Consolidation D Beams, Prisms, and Horizontal Creep Cylinders Insert the vibrator at intervals not exceeding 6 in. [150 mm] along the center line of the long dimension of the specimen, or along both sides but not in contact with the strain gage in the case of creep cylinders. For specimens wider than 6 in. [150mm], use alternating insertions along two lines. Allow the shaft of the vibrator to penetrate into the bottom layer approximately 1 in. [25 mm]. After each layer is vibrated, tap the outsides of the mold sharply at least 10 times with the mallet to close holes left by vibrating and to release entrapped air voids. External Vibration When external vibration is used, take care to ensure that the mold is rigidly attached to or securely held by: Engr. Vera Karla Caingles against the vibrating element or vibrating surface. Finishing by: After consolidation by any of the methods, strike off the surface of the concrete and float or trowel it in Engr. Vera Karla Caingles accordance with the method concerned. If no finish is specified, finish the surface with a wood or magnesium float. Perform all finishing with the minimum manipulation necessary to produce a flat even surface that is level with the rim or edge of the mold and which has no depressions or projections larger than 1Ú8 in. [3 mm].  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Laboratory Consolidation D Cylinders After consolidation finish the top surfaces by striking them off with the tamping rod where the consistency of the concrete permits, or with a wood float or trowel. If desired, cap the top surface of freshly made cylinders with a thin layer of stiff portland cement paste which is permitted to harden and cure with the specimen. Horizontally Cast Creep Cylinders After consolidation strike off the specimen with a trowel or float, then trowel the minimum amount required to form the concrete in the opening concentrically with the rest of the specimen. Use a screed curved to the radius of by: Engr. Vera Karla Caingles the specimen to more precisely shape and finish the concrete in the opening. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Laboratory Initial Curing To prevent evaporation of water from unhardened concrete, cover the specimens immediately after finishing, preferably with a non absorptive, nonreactive plate or a sheet of tough, durable impervious plastic. Specimens shall be stored immediately after finishing until the removal of the molds to prevent loss of moisture from the specimens. Select an appropriate procedure or combination of procedures that will prevent moisture loss and is non absorptive and nonreactive with the concrete. When wet burlap is used for covering, the burlap must not be in contact with the fresh concrete surface and care must be exercised to keep the burlap wet until the specimens are removed from the molds. Placing a sheet of plastic over the burlap will facilitate keeping it wet. To prevent damage to specimens, protect the outside of cardboard molds from contact with wet burlap or other sources of water until the molds are removed. Record the maximum and minimum ambient temperatures during the initial curing. by: Engr. Vera Karla Caingles Removal from Molds Remove the specimens from the molds 24 + 8 h after casting. For concrete with prolonged setting time, molds by: shall not be removed until 20 + 4 h after final set. If needed, determine the setting times in accordance with Engr. Vera Karla Caingles Test Method C 403/C 403M.  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Laboratory Curing Environment Unless otherwise specified all specimens shall be moist cured at 73.5 + 3.5 °F [23.0 + 2.0 °C] from the time of molding until the moment of test. Storage during the first 48 h of curing shall be in a vibration-free environment. As applied to the treatment of demolded specimens, moist curing means that the test specimens shall have free water maintained on the entire surface area at all times. This condition is met by using water storage tanks or a moist room in accordance with the requirements of Specification C 511. Cure structural lightweight concrete cylinders in accordance with Specification C 330. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Laboratory Curing Environment Flexural Strength Test Specimens Cure the flexural strength test specimens in accordance with Initial Curing and Removal from Molds except that while in storage for a minimum period of 20 h immediately prior to testing they shall be immersed in water saturated with calcium hydroxide at 73 + 3 °F [23 + 2 °C]. At the end of the curing period, between the time the specimen is removed from curing until testing is completed, drying of the surfaces shall be prevented. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making by: Engr. Vera Karla Caingles and Curing Concrete Test Specimens in the Field by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test SCOPE Specimens in the Field 1. This practice covers procedures for making and curing cylinder and beam specimens from representative samples of fresh concrete for a construction project. 2. The concrete used to make the molded specimens shall be sampled after all on-site adjustments have been made to the mixture proportions, including the addition of mix water and admixtures. This practice is not satisfactory for making specimens from concrete not having measurable slump or requiring other sizes or shapes of specimens. 3. The values stated in either SI units or inch-pound units are to be regarded by: Engr. Vera Karla Caingles separately as standard. The values stated in each system may not be exact by: equivalents; therefore, each system shall be used independently of the other. Engr. Vera Karla Caingles Combining values from the two systems may result in non-conformance with the standard.  Standard Practice for Making and Curing Concrete Test SCOPE Specimens in the Field 4. 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, health, and environmental practices and deter- mine the applicability of regulatory limitations prior to use. 5. The text of this standard references notes which provide explanatory material. These notes shall not be considered as requirements of the standard. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Field  This practice provides standardized requirements for making, curing, protecting, and transporting concrete test specimens under field conditions.  If the specimens are made and standard cured, as stipulated herein, the resulting strength test data when the specimens are tested are able to be used for the following purposes: Acceptance testing for specified strength, Checking adequacy of mixture proportions for by: Engr. Vera Karla Caingles strength, and by: Quality control. Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Significance and Use Specimens in the Field  If the specimens are made and field cured, as stipulated herein, the resulting strength test data when the specimens are tested are able to be used for the following purposes: Determination of whether a structure is capable of being put in service, Comparison with test results of standard cured specimens or with test results from various in- by: Engr. Vera Karla Caingles place test methods, Adequacy of curing and protection of concrete in by: the structure, or Engr. Vera Karla Caingles Form or shoring removal time requirements.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Molds Molds for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron, or other nonabsorbent material, nonreactive with concrete containing portland or other hydraulic cements. Molds shall conform to the dimensions and tolerances specified in the method for which the specimens are required. by: Engr. Vera Karla Caingles Molds shall hold their dimensions and shape under all conditions of use. by:Engr. Vera Karla Caingles Watertightness of molds during use shall be judged by theirability to hold water poured into them.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Molds by: Engr. Vera Karla Caingles by: Beam or Prism Mold Engr. Vera Karla Caingles Cylinder Mold  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Tamping Rods round, smooth, straight, steel rod with a diameter conforming to the requirements. The length of the tamping rod shall be at least 100 mm [4 in.] greater than the depth of the mold in which rodding is being performed, but not greater than 600 mm [24 in.] in overall length. The rod shall have the tamping end or both ends rounded to a hemispherical tip of the same diameter as the rod. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Vibrators Internal vibrators shall be used. The vibrator frequency shall be at least 150 Hz [9000 vibrations per minute] while the vibrator is operating in the concrete. The diameter of a round vibrator shall be no more than one-fourth the diameter of the cylinder mold or one-fourth the width of the beam mold. Other shaped vibrators shall have a perimeter equivalent to the circumference of an appropriate round vibrator. The combined length of the vibrator shaft and vibrating element by: Engr. Vera Karla Caingles shall exceed the depth of the section being vibrated by at least 75 mm [3 in.]. The vibrator frequency shall be checked by: periodically with a vibrating-reed tachometer or other Engr. Vera Karla Caingles suitable device.  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Mallets A mallet with a rubber or rawhide head weighing 0.6 + 0.2 kg [1.25 + 0.50 lb] shall be used. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Placement Tools Placement tools of a size large enough so each amount of concrete obtained from the sampling receptacle is representative and small enough so concrete is not spilled during placement in the mold. For placing concrete in a cylinder mold, the acceptable tool is a scoop. For placing concrete in a beam mold, either a shovel or scoop is permitted. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Finishing Tools - a handheld float or a trowel. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Slump Apparatus by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Sampling Receptacle The receptacle shall be a suit- able heavy gauge metal pan, wheelbarrow, or flat, clean nonabsorbent board of sufficient capacity to allow easy remix- ing of the entire sample with a shovel or trowel. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Air Content Apparatus The apparatus for measuring air content shall conform to the requirements of Test Methods C173/C173M or C231/C231M. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Apparatus Specimens in the Field Temperature Measuring Device The temperature measuring devices shall conform to the applicable require- ments of Test Method C1064/C1064M. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Testing Requirements Specimens in the Field Cylindrical Specimens Compressive or splitting tensile strength specimens shall be cylinders cast and allowed to set in an upright position. The number and size of cylinders cast shall be as directed by the specifier of the tests. In addition, the length shall be twice the diameter and the cylinder diameter shall be at least 3 times the nominal maximum size of the coarse aggregate. When the nominal maximum size of the coarse aggregate exceeds 50 mm [2 in.], the concrete sample shall be treated by wet sieving through a 50-mm [2-in.] sieve as described in Practice C172/C172M. For acceptance testing for specified compressive strength, cylinders shall be 150 by 300 mm [6 by 12 in.] or 100 by 200 mm [4 by 8 in.] by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Testing Requirements Specimens in the Field Beam Specimens Flexural strength specimens shall be beams of concrete cast and hardened in the horizontal position. The length shall be at least 50 mm [2 in.] greater than three times the depth as tested. The ratio of width to depth as molded shall not exceed 1.5. The minimum cross-sectional dimension of the beam shall be as stated in Table 2. Unless otherwise specified by the specifier of tests, the standard beam shall be 150 by 150 mm [6 by 6 in.] in cross section. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Testing Requirements Specimens in the Field When the nominal maximum size of the coarse aggregate exceeds 50 mm [2 in.], the concrete sample shall be treated by wet sieving through a 50-mm [2-in.] sieve as described in Practice C172/C172M. The specifier of tests shall specify the specimen size and the number of specimens to be tested to obtain an average test result. The same specimen size shall be used when comparing results and for mixture qualification and acceptance testing. Field Technicians by: Engr. Vera Karla Caingles The field technicians making and curing specimens for acceptance testing shall meet the person- nel qualification requirements of Practice C1077. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Molding Specimens Specimens in the Field A Place of Molding Mold specimens promptly on a level, rigid surface, free of vibration and other disturbances, at a place as near as practicable to the location where they are to be stored. B Casting Cylinders Select the proper tamping rod from Table 1 or the proper vibrator. Determine the method of consolidation from Table 3, unless another method is specified. If the method of consolidation is rodding, deter- mine molding requirements from Table 4. If the method of consolidation is vibration, determine molding requirements from Table 5. Select a scoop of the size described in 5.7. While placing the concrete in the mold, move the scoop around the perimeter of the mold by: Engr. Vera Karla Caingles opening to ensure an even distribution of the concrete with minimal segregation. Each layer of concrete shall be consolidated as required. In placing the final layer, add an amount of concrete that will fill the mold after consolidation. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Molding Specimens Specimens in the Field by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Molding Specimens Specimens in the Field by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Field Casting Beams C Determine the number of roddings per layer, one for each 14 cm2 [2 in.2] of the top surface area of the beam. Using the scoop or shovel, place the concrete in the mold to the height required for each layer. Place the concrete so that it is uniformly distributed within each layer with minimal segregation. Each layer shall be consolidated as required. In placing the final layer, add an amount of concrete that will fill the mold after consolidation. D Consolidation The methods of consolidation for this practice are rodding or internal vibration. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Field Rodding E Place the concrete in the mold in the required number of layers of approximately equal volume. Rod each layer uniformly over the cross section with the rounded end of the rod using the required number of strokes. Rod the bottom layer throughout its depth. In rodding this layer, use care not to damage the bottom of the mold. For each upper layer, allow the rod to penetrate through the layer being rodded and into the layer below approximately 25 mm [1 in.]. After each layer is rodded, tap the outsides of the mold lightly 10 to 15 times with the mallet to close any holes left by rodding and to release any large air bubbles that may have been trapped. Use an open hand to tap cylinder molds that are susceptible to denting or other permanent distortion if tapped with a mallet. After tapping, spade each layer of the concrete along the sides and ends of beam molds with a trowel or other suitable tool. Underfilled molds shall be adjusted with representative concrete during by: Engr. Vera Karla Caingles consolidation of the top layer. Overfilled molds shall have excess concrete removed. by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Field Vibration F Maintain a uniform duration of vibration for the particular kind of concrete, vibrator, and specimen mold involved. The duration of vibration required will depend upon the workability of the concrete and the effectiveness of the vibrator. Usually sufficient vibration has been applied as soon as the surface of the concrete has become relatively smooth and large air bubbles cease to break through the top surface. Continue vibration only long enough to achieve proper consolidation of the concrete (see Note 6). Fill the molds and vibrate in the required number of approximately equal layers. Place all the concrete for each layer in the mold before starting vibration of that layer. In compacting the specimen, insert the vibrator slowly and do not allow it to rest on the bottom or sides of the mold. Slowly withdraw the vibrator so that no large air pockets are left in the specimen. When placing the final layer, avoid overfilling by more than 6 mm [1Ú4 in.]. F.a Cylinders The number of insertions of the vibrator per layer is given in Table 5. When more than one insertion per layer is required distribute the insertion uniformly within each layer. Allow by: the vibrator to penetrate through the layer being vibrated, and into the layer below, about 25 Engr. Vera Karla Caingles mm [1 in.]. After each layer is vibrated, tap the outsides of the mold at least 10 times with the mallet, to close holes that remain and to release entrapped air voids. Use an open hand to tap molds that are susceptible to denting or other permanent distortion if tapped with a mallet.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Field F.b Beams Insert the vibrator at intervals not exceed- ing 150 mm [6 in.] along the center line of the long dimension of the specimen. For specimens wider than 150 mm [6 in.], use alternating insertions along two lines. Allow the shaft of the vibrator to penetrate into the bottom layer about 25 mm [1 in.]. After each layer is vibrated, tap the outsides of the mold sharply at least 10 times with the mallet to close holes left by vibrating and to release entrapped air voids. Finishing G Perform all finishing with the minimum manipulation necessary to produce a flat even surface that is level with the rim or edge of the mold and that has no depressions or projections larger than 3.3 mm [1Ú8 in.]. by: Engr. Vera Karla Caingles Cylinders G.a After consolidation, finish the top surfaces by striking them off with the tamping rod by: where the consis- tency of the concrete permits or with a handheld float or trowel. If Engr. Vera Karla Caingles desired, cap the top surface of freshly made cylinders with a thin layer of stiff portland cement paste which is permitted to harden and cure with the specimen. See section on Capping Materials of Practice C617/C617M.  Standard Practice for Making and Curing Concrete Test Procedure Specimens in the Field Beams G.b After consolidation of the concrete, use a handheld float or trowel to strike off the top surface to the required tolerance to produce a flat, even surface. Identification H Mark the specimens to positively identify them and the concrete they represent. Use a method that will not alter the top surface of the concrete. Do not mark the removable caps. Upon removal of the molds, mark the test specimens to retain their identities. by: Engr. Vera Karla Caingles by:Engr. Vera Karla Caingles  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Field Storage The supporting surface on which specimens are stored shall be level to within 20 mm/m [1Ú4 in./ft]. If specimens are not molded in the location where they will receive initial curing, ensure that the specimens have been moved to the initial curing location no later than 15 min after molding operations have been completed. If a specimen in a single-use mold is moved, support the bottom of the mold. If the top surface of a specimen is disturbed during movement to the place of initial storage, refinish the surface. Initial Curing Store standard-cured specimens for a period up to 48 h after molding to maintain the specified temperature and moisture conditions For concrete mixtures with a specified strength less than 40 MPa [6000 psi], maintain the initial curing by: Engr. Vera Karla Caingles temperature between 16 and 27°C [60 and 80°F]. For concrete mixtures with a specified strength of 40 MPa [6000 psi] or greater, maintain the initial curing temperature between 20 and 26°C [68 and 78°F]. Shield specimens from direct exposure to sunlight and, if used, radiant heating devices. Record the minimum by:Engr. Vera Karla Caingles temperature and maximum temperatures achieved for each set of specimens during the initial curing period.  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Field  A satisfactory temperature environment can be created during the initial curing of the specimens by one or more of the following procedures: (1) use of ventilation; (2) use of ice; (3) use of cooling devices; or (4) use of heating devices such as electrical resistance heaters or light bulbs. Other suitable methods may be used provided the temperature requirements are met.  Early-age strength test results may be lower if specimens are stored at temperatures lower than the specified range. At later ages, strength test results may be lower if specimens are exposed to initial curing temperatures higher than the specified range.  A satisfactory moisture environment can be created during the initial curing of the specimens by one or more of the following procedures: (1) immerse molded specimens with plastic lids in water; (2) store specimens in a by: Engr. Vera Karla Caingles container or enclosure; (3) place specimens in damp sand pits; (4) cover specimens with plastic lids; (5) place specimens inside plastic bags; or (6) cover specimens with wet fabric. by:  Immersion in water may be the easiest method to maintain required moisture and temperature conditions Engr. Vera Karla Caingles during initial curing.  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Field Final Curing Cylinders Upon completion of initial curing and within 30 min after removing the molds, cure specimens with free water maintained on their surfaces at all times at a temperature of 23.0 + 2.0°C [73.5 + 3.5°F] using water storage tanks or moist rooms complying with the requirements of Specification C511, except when capping with sulfur mortar capping compound and immediately prior to testing. When capping with sulfur mortar capping compound, the ends of the cylinder shall be dry enough to preclude the formation of steam or foam pockets under or in cap larger than 6 mm [1Ú4 in.] as described in Practice C617/C617M. For a period not to exceed 3 h immediately prior to test, standard curing temperature is not required provided free moisture is maintained on the cylinders and ambient temperature is between 20 and 30°C [68 and 86°F ]. by: Engr. Vera Karla Caingles Beams Beams are to be cured the same as cylinders (see 10.1.3.1) except that they shall be stored in water saturated by: with calcium hydroxide at 23.0+2.0°C [73.5 + 3.5°F] at least 20 h prior to testing. Drying of the surfaces of Engr. Vera Karla Caingles the beam shall be prevented between removal from water storage and completion of testing.  Standard Practice for Making and Curing Concrete Test Curing Specimens in the Field Field Curing Cylinders Store cylinders in or on the structure as near to the point of deposit of the concrete represented as possible. Protect all surfaces of the cylinders from the elements in as near as possible the same way as the formed work. Provide the cylinders with the same temperature and moisture environment as the structural work. Test the specimens in the moisture condition resulting from the specified curing treatment. To meet these conditions, specimens made for the purpose of determining when a structure is capable of being put in service shall be removed from the molds at the time of removal of form work. Beams As nearly as practicable, cure beams in the same manner as the concrete in the structure. At the end of 48 + 4 h after molding, take the molded specimens to the storage location and remove from the molds. Store specimens representing pavements of slabs on grade by placing them on the ground as molded, with their top by: Engr. Vera Karla Caingles surfaces up. Bank the sides and ends of the specimens with earth or sand that shall be kept damp, leaving the top surfaces exposed to the specified curing treatment. Store specimens representing structure concrete as near by: the point in the structure they represent as possible, and afford them the same temperature protection and Engr. Vera Karla Caingles moisture environment as the structure. At the end of the curing period leave the specimens in place exposed to the weather in the same manner as the structure. Remove all beam specimens from field storage and store in water saturated with calcium hydroxide at 23.0 + 2.0°C [73.5 + 3.5°F] for 24 + 4 h immediately before time