1.1 This test method covers the determination of the flexural performance of fiber-reinforced concrete expressed as energy absorption or residual strength in the post-crack range using a super-sized round panel supported on three symmetrically arranged pivots and subjected to a central point load. The performance of specimens tested by this test method is quantified both in terms of the energy absorbed between the onset of loading and selected values of central deflection and as residual strength at the selected values of central deflection. 1.2 This test method provides for the scaling of results whenever specimens do not comply with the target thickness and diameter as long as dimensions do not fall outside of given limits. 1.3 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. 1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
A new standard is proposed as a method of assessing the flexural performance of fiber-reinforced concrete using a super-sized round panel. The standard is being introduced to overcome some of the limitations of existing ASTM standards for quality control testing of fiber-reinforced concrete. ASTM C1609/C1609M is currently used for the assessment of flexural performance of FRC and is particularly useful for assessing the performance of thick (150+ mm) FRC members because the thickness of these beams is closer to that of most FRC structures than other specimens. However, data from QC tests undertaken in laboratories in America, Canada, Australia, England, Germany, Singapore, and Japan have indicated that ASTM C1609/C1609M suffers the disadvantage of exhibiting high within-batch variability in post-crack performance. For FRC used in many pre-cast concrete applications, which typically involves 50- to 60-mm long steel or macro-synthetic fibers at moderate dosages, the within-batch coefficient of variation in post-crack performance for sets of ASTM C1609/C1609M beams often exceeds 20 %. This poor repeatability in post-crack performance introduces problems in QC necessitating higher dosages of fiber, which increases the cost of FRC in these applications. ASTM C1550 provides for the assessment of post-crack performance for thin FRC members (around 75 mm thick) and exhibits the advantage of very low within-batch variability. The limitation of this test method is that a 75-mm-thick specimen does not adequately model the performance of thick (150+ mm) FRC elements, and thus, the results of ASTM C1550 tests are not directly applicable to thick FRC structures. There is presently no standard test method for flexural performance assessment that is applicable to thick (150+ mm) FRC members while at the same time exhibiting very low within-batch variability. This new standard test method combines the advantages of ASTM C1609/C1609M and ASTM C1550 because it involves a 150-mm-thick specimen and exhibits very low within-batch variability. The test method is already being used for QC of pre-cast FRC elements in Australia where the COV in post-crack performance for pairs of specimens has been found to average about 3 %. This very good level of repeatability results in immediate economic advantages to pre-cast concrete contractors who have adopted this test method enthusiastically. The test method and procedure is similar to ASTM C1550 but differs in several ways as a result of the larger size of the specimen (150 mm thick and 1200-mm diameter). The weight of the specimen necessitates mechanical handling, but this is not a problem for pre-cast concrete contractors and represents only a minor challenge for laboratories that already undertake ASTM C1550.
Keywordsenergy absorption; fiber-reinforced concrete; flexure; post-crack behavior; toughness
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Draft Under Development