ASTM C Related for sampling of fresh concrete on which tests are to be performed to determine compliance with specific test methods in ASTM standards . Materials. Sampling. Testing. C Cement. C Agg. C Air. C Admix. C Ash. C Water. C Sampling Fresh Concrete. ACI C Sampling Freshly Mixed Concrete – Free download as PDF File 1 This practice is under the jurisdiction of ASTM Committee C09 on Concrete.
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ASTM C / CM – 17 Standard Practice for Sampling Freshly Mixed Concrete
The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. NOTE 1—Composite samples are required by this practice, unless specifically excepted by procedures governing the tests to be performed such as tests to determine uniformity of consistency and mixer efficiency. Procedures used to select the specific test batches are not described in this practice, but it is recommended that random sampling be used to determine overall specification compliance.
This removal of larger aggregate particles is preferably accomplished by wet-sieving. 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 are caustic and may cause chemical burns to skin and tissue upon prolonged exposure. The detailed requirements as to astn, mixtures, air content, temperature, number of specimens, slump, interpretation of results, and precision and bias are in specific test methods. They shall be combined and remixed with a shovel v172 minimum amount necessary to ensure uniformity and compliance with the maximum time limits specified in 4.
Complete these tests expeditiously. Start molding specimens for strength tests within 15 min after fabricating the composite sample.
Expeditiously obtain and use the sample and protect the sample from the sun, wind, and other sources of rapid evaporation, and from contamination. Current edition approved Oct. Originally approved in Last previous edition approved in as C— No further reproductions authorized. Smaller samples are not prohibited for routine air content, temperature, and slump tests. The size of the samples shall be dictated by the maximum aggregate size.
NOTE 2—Sampling should normally be performed as the concrete is delivered from the mixer to the conveying vehicle used to transport the concrete to the forms; however, specifications may require other points of sampling, such as the discharge of a concrete pump. Mixers—Sample the concrete by collecting two or more portions taken at regularly spaced intervals during discharge of the middle portion of the batch.
Obtain these portions within the time limit specified in Section 4.
Combine into one composite sample for testing purposes. Do not obtain portions of the composite sample from the very first or last part of the batch discharge Note 3. Perform sampling by passing a receptacle completely through the discharge stream, or by completely diverting the discharge into a sample container. If discharge of the concrete is too rapid to divert the complete discharge stream, discharge the concrete into a container or transportation unit sufficiently large to accommodate the entire batch and then accomplish the sampling in the same manner as given above.
Take care not to restrict the flow of concrete from the mixer, container, or transportation unit so as to cause segregation. These requirements apply to both tilting and nontilting mixers. Due to the difficulty of determining the actual quantity of concrete discharged, the intent is to provide samples that are representative of widely separated portions, but not the beginning and the end of the load.
Active Risk Management
Obtain samples from at least five different portions of the pile and combine them into one composite sample for test purposes. Avoid contamination with subgrade material or prolonged contact with and absorptive subgrade. To preclude contamination or absorption by the subgrade, sample the concrete by placing three shallow containers on the subgrade and discharging the concrete across the container.
Combine the samples so obtained into one composite sample for test purposes. The containers shall be of a size sufficient to provide a composite sample size that is in agreement with the maximum aggregate size. NOTE 4—In some instances, the containers may have to be supported above the subgrade to prevent displacement during discharge. Agitators—Sample the concrete by collecting two or more portions taken at regularly spaced intervals during discharge of the middle portion of the batch.
Take the samples so obtained within the time limit specified in Section 4 and combine them into one composite sample for test purposes. In any case do not obtain samples until after all of the water and any admixtures have been added to the mixer; also do not obtain samples from the very first or last portions of the batch discharge Note 3. Sample by repeatedly passing a receptacle through the entire discharge stream or by completely diverting the discharge into a sample container.
Regulate the rate of discharge of the batch by the rate of revolution of the drum and not by the size of the gate opening. Sample the concrete at the frequency specified by collecting two or more portions taken at regularly spaced intervals during discharge of the concrete. Take the portions so obtained within the time limit specified in Section 4, and combine them into one composite sample for test purposes.
After obtaining the composite sample, wait a minimum of 2 minutes and a maximum of 5 minutes before beginning tests Note 5. NOTE 5—The waiting period prior to commencing the testing is needed because the mix water is input only seconds before discharge from the continuous mixer. NOTE 6—The effect of wet-sieving on the test results should be considered. For example, wet-sieving concrete causes the loss of a small amount of air due to additional handling.
The air content of the wet-sieved fraction of concrete is greater than that of the total concrete because the larger size aggregate which is removed does not contain air. The apparent strength of wet-sieved concrete in smaller specimens is usually greater than that of the total concrete in larger appropriate size specimens.
The effect of these differences may need to be considered or determined by supplementary testing for quality control or test result evaluation purposes. Generally, a horizontal back and forth motion is preferred. The equipment shall be capable of rapidly and effectively removing the designated size of aggregate.
This shall be done before remixing.
Shake or vibrate the sieve by hand or mechanical means until no undersize material remains on the sieve. Mortar adhering to the aggregate retained on the sieve shall not be wiped from it before it is discarded. Place only enough cc172 on the sieve at any one time so that after sieving, the thickness of the layer of retained aggregate is not more than one particle thick.
The concrete which passes the sieve shall fall into a batch pan of suitable size which has been dampened before use or onto a clean, moist, nonabsorbent surface.
Scrape any mortar adhering to the sides of the axtm equipment into the batch. After removing the larger aggregate particles by wet-sieving remix the batch with a shovel the minimum amount necessary to ensure uniformity and proceed testing immediately. Committee C09 has identified the location of selected changes to this practice since the last issue, C—14, that may impact the use of this practice.
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