Phil
Registered User
Concrete is typically too stiff to be used as grout. The National Concrete Masonry Association's (NCMA) TEK 3-2A Grouting Concrete Masonry Walls and TEK 9-4A Grout for Concrete Masonry are good references. The NCMA publishes TEK manuals that provide a plethora of useful information on masonry. The guides can be downloaded for free from NCMA sponsors: http://www.ncma.org/resources/design/Pages/Map_Sponsor.aspx .