When drying SFRM for density testing, what is the maximum allowable relative humidity?

The correct choice regarding the maximum allowable relative humidity when drying Spray-Applied Fire-Resistive Material (SFRM) for density testing is based on industry standards and practices. Maintaining a relative humidity level at or below 60% is crucial because higher humidity can adversely affect the drying process of the SFRM, leading to inaccurate density measurements.

When humidity exceeds this threshold, it may hinder the evaporation of moisture from the material, potentially resulting in the retained water content skewing the results of the density tests. As density is a key factor in determining the effectiveness and performance of SFRM, adhering to this limit ensures that the material is tested under conditions that best reflect its intended application and service conditions.

Therefore, the choice of 60% as the maximum relative humidity ensures reliability in density testing, contributing to the overall structural integrity and performance assessment of the fireproofing material.