Which statement about SSD conditioning is true?

Which statement about SSD conditioning is true?

• A. Samples dried past the SSD condition must be immersed in water for 30 minutes prior to resuming the process of surface-drying.
• B. The sample is covered with water either by complete immersion or by adding approximately 6 % moisture.
• C. The specified time period for the sand to soak in the water is 24-48 hours.
• D. Pycnometers are calibrated by filling them with water at 23 ± 1.7 °C (73.4 ± 3 °F) to the calibration line and determining the mass.

Answer: (A)

Saturated Surface Dry conditioning means the aggregate pores are filled with water but the surface is dry, so moisture won’t affect mass measurements in asphalt testing. When a sample has been dried past SSD, the proper reconditioning step is to immerse it in water for about 30 minutes, then remove surface water and resume surface-drying to return to the SSD state before continuing. This rehydration without leaving a wet surface ensures consistent test results. The other descriptions don’t fit: soaking for 24–48 hours is unnecessarily long for reconditioning; tying SSD to a fixed moisture percentage like around 6% doesn’t reflect how SSD is defined (it’s about the surface condition and pore saturation, not a set percent); and calibrating a pycnometer is a separate procedure unrelated to SSD conditioning.

Saturated Surface Dry conditioning means the aggregate pores are filled with water but the surface is dry, so moisture won’t affect mass measurements in asphalt testing. When a sample has been dried past SSD, the proper reconditioning step is to immerse it in water for about 30 minutes, then remove surface water and resume surface-drying to return to the SSD state before continuing. This rehydration without leaving a wet surface ensures consistent test results.

The other descriptions don’t fit: soaking for 24–48 hours is unnecessarily long for reconditioning; tying SSD to a fixed moisture percentage like around 6% doesn’t reflect how SSD is defined (it’s about the surface condition and pore saturation, not a set percent); and calibrating a pycnometer is a separate procedure unrelated to SSD conditioning.