To eliminate air pockets and voids under the base, which method is used?

Using a fine aggregate free grout is effective for eliminating air pockets and voids under the base because this type of grout can fill in small spaces due to its fine particle size, allowing for better compaction and adhesion to surfaces. Fine aggregate free grout typically provides a fluid consistency that enhances its ability to flow into tight spots and displace air pockets during the placement process.

This ensures that the grout uniformly supports the base, reducing the risk of future settling or movement caused by voids. A properly mixed fine aggregate free grout will also create a stronger bond between the base and the foundation it is being poured upon, which is crucial for maintaining structural integrity.

Though other methods listed might have their uses in different contexts, they don't specifically address the challenge of eliminating air pockets as efficiently as a fine aggregate free grout.