The mortar mix I used for 5 years started cracking after 9 months

I always used the same bagged mortar mix from the hardware store, standard stuff. Then about a year ago I switched to a local supplier's premix because it was $3 cheaper per bag. At first it looked fine but after 9 months I noticed hairline cracks running through the joints on a retaining wall I built. I went back and checked three other jobs I did with that mix and they all have the same issue. Has anyone else seen a big difference between bagged brands like this?

3 comments

3 Comments

paul1171mo ago

Read somewhere that cheap premixes sometimes use more sand and less Portland to cut costs, and that can mess with the bond over time. Explains why the cracks showed up after a few months. Might be worth testing a bag from the old supplier to see if it holds up better.

dylanward2d ago

Maybe check if the mix had any additives in it. Some cheap stuff uses finer materials that just don't lock together right. Water to cement ratio matters more than people think. Too much water hiding in the sand can ruin the bond from day one. Could also be a curing issue - cheap bags might not have the right retarders for hot weather. It's a whole chain of problems, not just one thing.

bettykim1mo ago

@paul117 Totally agree, switching suppliers fixed similar cracking issues for me.