How to repair this?

JohnSwift10

What is the best way to repair this without buying a bag of cement and sand when I only need a fraction of a bag?

daveyjp

Tub or tube of repair cement,

https://www.screwfix.com/p/no-nonsense-504-concrete-repair-grey-300ml/727GC

https://www.screwfix.com/p/no-nonsense-all-purpose-mortar-grey-5kg/955gl

plumb1_2

Go for the 5kg mix from screwfix
plus use a bonding agent, not pva 

stuart45

plumb1_2 said:

Go for the 5kg mix from screwfix
plus use a bonding agent, not pva 

Good to see you back @plumb1-2. There's a backlog of plumbing questions for you. 
I guess you mean adding SBR instead of PVA.

Ectophile

You can buy ready mix sand & cement in a tub from the DIY sheds.  Just add water.  Don't assume that the amount of water it says on the tub is correct.

If you want something more lumpy, you can get ready mix concrete in a tub too.  The lumps are much smaller than the stones in normal concrete.

EssexExile

Personally I'd save my money and leave it.

Eldi_Dos

Rake out any loose bits then brush in matching sand, top up the sand as need be, a bag of sand will last a long while.

Any amateur repair runs the risk of making things appear worse.

plumb1_2

stuart45 said:

plumb1_2 said:

Go for the 5kg mix from screwfix
plus use a bonding agent, not pva 

Good to see you back @plumb1-2. There's a backlog of plumbing questions for you. 
I guess you mean adding SBR instead of PVA.

Hi Stuart45, ya been in hibernation 😂
ya use sbr,   I avoid pva, just turns to mush with any sort of moisture. 

WIAWSNB

JohnSwift10 said:

What is the best way to repair this without buying a bag of cement and sand when I only need a fraction of a bag?

What is that concrete strip? How wide? What does it all look like? 

I have used Davey's suggestion of the no-nonsense mortar cartridge, and found it great stuff. I used it to fill cracks and missing bits in concrete, and it's driven over a few times a day. Easy to shape and tap into place, has a nice gritty texture like sandy mortar, and doesn't even stick to your fingers. 

However, it is an even grey colour, so is unlikely to match your existing concrete. Any chance you might want to paint that concrete strip to tidy it up? If so, then fill away. 

At only a few quid, might even be worth a test? Brush out and clean the gaps thoroughly. Slip a thin strip of summat - plastic or whatever - alongside the blocks so you can pack tightly up to it whilst leaving a neat edge. Texture the finish to match as closely as possible before it sets. 

plumb1_2

I would personally get a grinder with a diamond blade and use a straight edge to cut the concrete back another 20/30 mm .
Dig the debris out, prime both sides, then use something like Sika joint compound or an expoxy compound. You can also buy a rubberised expansion joint compound in a mastic type tube, can’t remember the name of it. 
As just trying to patch it like it is most probably will crack up 

oh the deeper to can remove the debris the better min 50 mm