U-Can repair mortar not setting

[phatboy]

Hi all,

In order to get a wall flattened out quickly today, I bought from B&Q a tub of U-Can repair mortar. http://www.diy.com/departments/u-can-brick-wall-repair-mortar-5kg-tub/242770_BQ.prd

It says you just add 300ml of water to 2.5Kg of mortar, apply and 2 hours later it will be set.

Well after 6 hours it was still soft and a bit flakey. The room has just been plastered yesterday so the air is probably fairly moist. I have stuck a heater in the room overnight.

Any ideas if it is likely to be slow due to the moisture, or will I be scrapping it off again tomorrow morning and buying something better from the builders merchant?



Thanks
Tim

 

[r896neo]

Normal mortar will still be soft for 8 hours and even the next day will seem firm but still take a slight imprint from a thumb and be easily gouged with a screwdriver etc.

Repair mortar implies it might be rapid setting cement in which case it would be close to fully hydrated and hardened within a few hours?

Just checked and its normal OPC not rapid set so should be alright in the morning hopefully.

 

[^woody^]

Setting and hardening are two different processes.

That product is made specifically for the gullible. It's just sand and cement removed from horrible-looking builders bags, and put into nice consumer friendly tins.

The drying time will depend on the material it is applied to and not the moisture in the air. Applying heat to drying cement mortar is the worst thing to do. It will dry too soon and become soft and brittle and loose adhesion.

But above all, you have bought mortar which is for laying bricks and will always be soft. It's not the correct product for bringing out walls. You need render for that.

 

[phatboy]

Thanks all for the advice. B&Q was closer than the usual merchant so I cheated, and regretted it.

I got the job done, and it was dry after 36 hours. It got the wall flat and is now covered up so no problem.

So no more B&Q, regardless of time saving short term!!