Practice question

What is the characteristic compaction action of a pneumatic (rubber-tired) roller on HMA compared with a steel-wheel roller?

It only cuts the longitudinal joint and cannot be used on the main mat
It kneads the mix, which helps density and seals surface voids, while a steel-wheel roller provides a smoother finished surface
It is the only roller allowed after the mat cools below 175°F because it vibrates the stone matrix
It is used only to apply tack coat by driving through the emulsion

Answer: B — It kneads the mix, which helps density and seals surface voids, while a steel-wheel roller provides a smoother finished surface

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