Bricks, Masonry, Asphalt and Concrete - How To Tuckpoint Flagstone Walkway

I have a walkway that I think is made of granite or slate. The surface is smooth and the stones are various shapes/sizes. The width of the tuckpointing between the stones varies from 1/2 inch to approx 1 - 1.5 and is crumbling in spots. Can anyone recommend where I can find instructions on tuckponting horizontal surfaces? Also, I would be interested in hearing about any additives that be added to the mortar to help prevent cracking.

What is under the stone? Is it concrete or soil?

If you do not have concrete, you will not be able to avoid cracks. The width of the cracks also contibutes to the cracking.

Dick

I believe the flagstones cover a regular poured concrete porch. I don't know why the owners decided to cover the concrete porch, but they did. The mortar is really old and I thought maybe there was some new additive to mortar these days that makes it more resilient to the weather.