ASTM D7857-16

5.1 The properties evaluated by this test method are intended to provide comparative information on the effects of fire-retardant chemical formulations and environmental conditions on the flexural properties and IB strength of FRSC panels.

5.2 This practice uses a controlled elevated-temperature environment to produce temperature-induced losses in the mechanical properties of FRSC panels and untreated panels.

5.3 Prediction of performance in natural environments has not been directly correlated with the results of this test method.

5.4 The reproducibility of results in elevated-temperature exposure is highly dependent on the type of specimens tested and the evaluation criteria selected, as well as the control of the operating variables. In any testing program, sufficient replicates shall be included to establish the variability of the results. Variability is often observed when similar specimens are tested in different chambers even though the testing conditions are nominally similar and within the ranges specified in this test method.

1.1 This test method is designed as a laboratory screening test. It is intended to establish an understanding of the respective contributions of the many wood material, fire-retardant, resin and processing variables, and their interactions, upon the mechanical properties of fire-retarded mat-formed wood structural composite (FRSC) panels as they affect flexural and internal bond (IB) performance and as they are often affected later during exposure to high temperature and humidity. Once the critical material and processing variables have been identified through these small-specimen laboratory screening tests, additional testing and evaluation shall be required to determine the effect of the treatment on the panel structural properties and the effect of exposure to high temperature on the properties of commercially produced FRSC panels. In this test method, treated structural composite panels are exposed to a temperature of 77°C (170°F) and at least 50% relative humidity.

1.2 The purpose of the preliminary laboratory-based test method is to compare the flexural properties and IB strength of FRSC panels relative to untreated structural composite panels with otherwise identical manufacturing parameters. The results of tests conducted in accordance with this test method provide a reference point for estimating strength temperature relationships for preliminary purposes. They establish a starting point for subsequent full-scale testing of commercially produced FRSC panels.

1.3 This test method does not cover testing and evaluation requirements necessary for product certification and qualification or the establishment of design value adjustment factors for FRSC panels.

1.4 This test method is not intended for use with structural plywood.

1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.

1.6 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.