re attach sandstone veneer

[magnet 12]

I noticed three 12cm x 12cm pieces of sandstone veneer ( about 15mm) thick had loosened from the vertical sides of our front step surrounds.I removed them to prevent damage in case they fell.
Can anyone suggest the best adhesive to fix sandstone back onto a vertical brick surface.Ideally it will be something which gives a quick initial grab since it will be hard to hold them while adhesive sets.I thought about a bondcrete/mortar slurry but too slow setting and am not sure if the silicone products would hold to a sandstone product.
Thanks in advance for any ideas.

[Terrian]

Something like liquad nails perhaps ???

[autogenous]

Do you have a picture?

Its easier to establish what is going on.

What was used to adhere them in the first place?

Possibly some tilers flexible adhesive?

Liquid nails might be ok but I don't know much about its uses. It does stick. Is liquid nails ok for external use?

[Terrian]

Liquid nails might be ok but I don't know much about its uses. It does stick. Is liquid nails ok for external use?

Yeah, but there are also some other construction adhesives available...

[Burnsy]

Something like liquad nails perhaps ???

Liquid nails is as useless as it's name suggests. Use a flexible adhesive made by Parchem called Ductseal SB (SB stands for solvet based). It has no thickness so can be used to re-attach where morter has failed as is likely the case for you. It is used widely in the Landscaping industry to stick pool headers on. I have used it for years along with most other landscapers in Perth and never had a comeback. It takes about a week to gain full strength so don't put any stress on the cladding for that period.