What is the proper grout for exterior limestone walkway?

Q. What is the proper grout for an exterior limestone walkway? Is there a dry grout that can be swept between the stone? Where would I look for stone dust?

A. The proper grout will depend on how the stone is set. Will it be set in mortar or placed on a dry sand bed? Also where are you located? Winter will also determine what type of grout to use.

Q. Limestone is set on dry sand bed. We are located in Northern Michigan, 1 hour south of the bridge between the two peninsulas. We have heavy freeze and thaw cycles.

A. I would not use a cement based grout. Simply sweep some fine sand into the joints.

Fred Hueston
Chief Technical Director, SurpHaces
President, Stone Forensics