Which material should be used to fill voids when smoothing a test site?

• A. Native fines to fill voids
• B. Cement
• C. Sand
• D. Gravel

Answer: (A)

Filling voids with native fines is preferred because it uses material already present at the site, matching the in-place soil in grain size and moisture characteristics. This helps achieve uniform compaction and surface finish without introducing a material that behaves differently under load. Cement would harden and distort grading and drainage, making the surface stiff and prone to cracking. Sand can drain and segregate, changing the density and finish, while gravel introduces larger voids and disrupts smoothness. Using native fines keeps the smoothing process true to the existing soil behavior, avoiding these issues.