In my front yard I have a curved walkway made out of cement. The cement walkway is about 45 inches wide and sits on top of some compacted dirt.

This past weekend I used some exterior thinset mortar (rated for outdoor use and wet conditions) to mortar concrete pavers to the walkway.

My question is related to "grouting the joints".

  • since I have a concrete base and no where for the water to drain, do I need to use polymer mortar to fill my joints?
  • Or can I get away with using a polymer sand sweeping it in the joints and watering it down?

2 Answers 2


You can use cement based grout.

Cement based has been used long prior to polymer grouts. I haven’t used polymer or epoxy grouts outside but they work great in the bathroom.

I have used addmix in my grout but I also use this in my mortar.


How big are the joints? If they are small, use the polymer sand swept in. If they are larger use a masons grout bag to fill with regular masonry cement.

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  • Thanks Jack - does it matter if the polymer sand is permeable? That is my only concern is the water will go through the joints and have no where to drain too... although maybe this doesn't matter??
    – Andrew
    Commented Apr 5, 2021 at 1:35
  • 1
    It's all permeable, the brick mortar and polymer sand. each of the mixes suggested are suited to fill the whole joint, from bottom to top. The idea is to allow no voids where water can collect freeze and pop stuff loose. If it all freezes collectively, it will stay intact. If one area has a void where ice can form as a solid mass, then hydraulic action set up where it can pop things loose. It takes a lot, but it can. I was in MD for decades and demoed enough to see things could handle small voids, but the idea is to have none.
    – Jack
    Commented Apr 5, 2021 at 13:53

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