ASTM C359-20 PDF Download

Standard Test Method ASTM C359-20 is used to determine the early stiffening of hydraulic-cement mortar. The purpose of this test is to assess the degree to which a cement mortar undergoes early stiffening. The test method provides a means for estimating the relative tendency of a cement to exhibit early stiffening, allowing differentiation between a relatively less serious and less persistent tendency (false set) and a more serious and persistent tendency (flash set).

Severe false setting in a cement may cause difficulties in placing and handling, particularly in scenarios where concrete is mixed for a short period of time in stationary mixers and transported to the forms in non-agitating equipment. However, it is less likely to cause problems in transit mixing or when concrete is remixed prior to placing or transporting. Cements with severe false setting may require slightly more mixing water to achieve the desired consistency and can result in slightly lower strengths and increased drying shrinkage.

It is important to note that early stiffening resulting from false set is not likely to cause a cement to fail the applicable time of setting requirement. However, early stiffening resulting from flash set, depending on its severity, can cause a cement to fail the applicable time of setting requirement. The standard also mentions that explanatory notes and footnotes provided in the text should not be considered as requirements of the standard.