Joined: July 2004
||Posted: 22 May 2019,09:40
That looks like it could be either a proprietary cement mortar such as TuffTop or an outdoor grade tile grout.
Bear in mind that light-coloured jointing only remains light-coloured if you keep it meticulously clean. Left unattended, it will go mucky brown, like all jointing does eventually.
The way to make your own such mortar is to use a silver sand with white cement - read more [http://www.pavingexpert.com/light_flags_01.htm#ingred]here[/url]
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