Which statement about SSD conditioning is true?

• A. The sample is covered with water either by complete immersion or by adding approximately 6 % moisture.
• B. When performing the cone test to check the condition of the sand, permit the tamper to fall freely from 50 mm over the top of the sand.
• C. The specified time period for the sand to soak in the water is 24-48 hours.
• D. If surface moisture is still present in the sample, then the sand will retain its molded shape when the mold is lifted vertically.

Answer: (A)

SSD conditioning targets a Saturated Surface Dry state for the aggregate, where all the pores are filled with water but there is no free moisture on the surface. This helps ensure consistent density measurements and molding behavior in tests.

The best statement describes bringing the sample to SSD by either fully immersing it in water or adding enough moisture—about 6%—so the pores are saturated and any excess surface water can drain away, leaving a dry surface. This approach matches the practical way technicians achieve SSD: you don’t want surface moisture causing stickiness or cohesion during molding, yet you need to saturate the internal pores to a known level.

The other statements aren’t correct for SSD conditioning because: the cone test involves a density determination method separate from conditioning the material to SSD; a fixed soak time (24–48 hours) isn’t the defining or reliable method to reach SSD, since moisture content and drainage are the controlling factors; and if surface moisture remains, the sample will tend to cling or hold its molded shape, which indicates the surface is not dry and the material isn’t in SSD.