You could water blast it, then use some of that 30 seconds cleaner or similar to get the rest of the gunge off.

Clean it up, and use pave lock sand (with cement in it) to fill in the joints.

You will find instructions and video on this.  Will need to take care not to break up the bricks though.

kotuku4:

 

Clean it up, and use pave lock sand (with cement in it) to fill in the joints.

 

You will find instructions and video on this.  Will need to take care not to break up the bricks though.

 

I think the joints/gaps are too big for pavelock sand. I was considering repointing but that seems like a lot of work.

Could use a dry placement method as per pave lock.  Possibly with more cement added in the mix.

Mortar for pointing is just a low strength cement in fine to medium sand.  I am having to re point the brick on my house, as the brick layer cut corners and used a sharp medium sand with not enough cement and it is eroding.   

timmmay:

 

You could water blast it, then use some of that 30 seconds cleaner or similar to get the rest of the gunge off.

 

If you waterblast it, do it with some care. If you use too much pressure and too close to the surface, you may do more damage than good. 

@Dulouz,

I have a brick pathway alongside the house, about 1 meter wide and some 10 metres long …. was laid new about 15 years ago and it has always gone gunky with weeds and mould on a regular basis.

Water blasting made it look great for a few weeks only, and was harsh on the grouting.  Tried a number of weed killer sprays and also those "spry-and-walk-away" stuff …. all with no lasting effect at all.  same with soapy hot water, bleach solutions, and commercial "path cleaners".

The trouble is that bricks are porous and allow ingress of water, dust and seeds etc.

Summer months it is pretty good because nothing grows then and dead plant/lichen is easily hard-brushed off, but the weeds and green return after periods of rain.

Your one looks quite uneven, which could be dangerous for walking on, so maybe getting it relaid properly is appropriate?  After that, regular attention by spraying and scraping is the only answer I know of.