Concrete repairs

[saka]

Would any kind and preferably knowledgeable soul be able to advise me on
a wee concrete repair problem I have, please?

A hairline crack approx 3 feet long has appeared in a section of my
print pave concrete patio. The concrete was originally laid to a minimum
depth of 100mm, and the crack spans the entire width of the section
concerned.

After chiselling out a V-groove along its entire length, I did attempt a
DIY repair using some readymix brick mortar about 2 months ago, but the
crack has reappeared presumably because of movement caused by expansion
and contraction.

I have done some Googling around but with limited success, and am
confused by the products on offer as most seem geared towards the
building/construction trades rather than DIY. The nearest I can find to
what I think are my requirements is this site:

http://www.radonseal.com/crack-injection/slab-cracks.htm

but the product (CrackWeld) is only available in the USA, from what I
can see.

Does anyone know of a similar product or technique available here in
good ole Blighty?

Cheers
Steve