Crumbling mortar joints - new wall

[GinSoakedBoy]

Hopefully someone can offer advice on the next course of action?

I have been laying some blocks for a retaining wall in the garden. First few sessions have gone well, however having a poke at the last run I did I am concerned the mortar is far to crumbly. Admittedly due to time constraints I have had to lay these blocks in the hot weather. I have been wetting the blocks as I lay them but appreciate in high heat and full sun there is a chance the mix dried before it cured. Did cover themn over but with the heat / sun its been ineffective.

Images attached. I have easily raked this out with a bucket trowel. Other sections of the wall that were laid in similar heat (but with more shade) have firm mortar joints. Having properly investigated a few joints the middle of the joint is a lot firmer - clearly that had time to cure before it dried.

Video here

IMG_2991.MOV

drive.google.com

Options.

1. Should I redo the last 12 blocks with the bad mortar, combination of raking the joints and a hammer and bolster. Annoying but at least I know its sound.

2. Its fine, leave it at it is, rake out the loose stuff to firm mortar and remortar the joints. Next time dont work in such high heat / sunshine.



- Some background

Whilst this is a retaining wall its not actually retaining anything as such, behind it is solid stone with 10 inches of soil. The wall is 800mm high.

The wall will be rendered once finished if that makes any difference.

Thanks in advance for the advice

 

[^woody^]

Yes, the joints have dried too quickly. Any powdery joints will be quickly eroded by weathering and especially frost action - which in turn can promote the rest of the joint to crack.

The best way to prevent this in future is to cover the wall with polythene or damp hessian for a few days after laying.

Rake out the bad joints to 25mm deep and repoint.

 

[jj4091]

Rake out the bad joints to 25mm deep and repoint.

Is that really necasary when it is going to be rendered

 

[noseall]

Is that really necasary when it is going to be rendered

No. Brush off loose material.

 

[stuart45]

If you rake out and don't repoint it gives a key for the render. There was a time on new builds you had to rake out the joints on internal brickwork for that reason.

 

[noseall]

If you rake out and don't repoint it gives a key for the render. There was a time on new builds you had to rake out the joints on internal brickwork for that reason.

I remember one plasterer asking us to rake the blockwork (Celcons) on a house we built in the '80's. It was wet plastered with Carlite Browning.

 

[GinSoakedBoy]

Thanks for the responses gents. In the end I raked out the joints. Honestly didnt take that long with an old crappy chisel. Went back until I hit the first stuff and then repointed. At leats now I know the joints are good and strong. Also went down to the merchants and bought a hessian roll. Thats helped slow the curing time down so the sun/heat doesnt bake the mortar before it has time to set.