What to use to glue rocks together, liquid cement, etc...

[railroader21]

I've been recently constructing my LGB layout and I would like to know what to use to glue rocks together.  Not rocks like round rocks, but flat rocks, sort of like flagstone.  I want to stack them vertically and glue them together as I build it up.  I will then fill it with pea gravel and cushed marble chips.  Any help will be appreciated, Thank you

[ttrigg]

Two quick questions. 1) Indoors or outside? 2) I could have easily misread but sounds like you are planning on stacking flat stones vertically? Are you talking about laying the flat sides flat and stacking one atop the other? Or do you mean attaching the flat side to a vertical surface?

If indoor or outdoor and laying the flat side down, then use a construction adhesive, one designed for brick. Use one packaged for use in a caulking gun. If the flat side is going vertical use cement mortar, and do one row at a time, allowing the mortar to set slightly before putting the second row in place.

[grandpopswalt]

There was an article in GR a little while back that talked about using Polyurethane glue to cement bricks and concrete blocks together in an outdoor location.

Walt

[g. gage]

There was an article in GR a little while back that talked about using Polyurethane glue to cement bricks and concrete blocks together in an outdoor location.

Walt

I glued a broken concrete block with a concrete glue and it came apart after a couple of years. It may have been caused by the weather, here in the Sierra Nevada we had 4' of snow and temperatures of -15 that year.

Rob

[Ray Dunakin]

I started out using a polyurethane glue to join the rocks on my layout, but soon switched to mortar. The polyurethane glue expands as it cures, but before it does, it's very runny and dribbles out of the gaps. If you get a good, close bond it will hold up quite well -- it worked fine for joining concrete bricks. But on rocks it didn't work as well. Something like Liquid Nails would be a better choice.

However, I'd recommend mortar. It's pretty easy to work with and can be stained to match the color of the rocks, and it's a tried-and-true solution.

[thegman]

I've read your question concerning glueing your rocks together and I want to give you my point of view on this subject. First, not knowing if it is indoor or outdoor, it does make a difference. To start off Indoors. I would use a Polyurathene glue such as a Gorilla or Elmers glue. This can be bought at the local Big Box Home Improvement store or at the local Hardware store. The difference between these two Brands of glue is in the Shelf life, which is the amount of time that the bottle is open. I've found that Gorilla glue has a very short shelf life, even after squeezing the bottle dry of all the air inside it, before putting the cap on. Elmers has a longer shelf life and sticks just as good as Gorilla.  

First, Make sure your rocks are scrubbed and washed clean and free of any dirt or loose particles. Do Not use soap; but do use a Nylon Bristle brush to quickly scrub them. This definately is an outside job for larger rocks. They do not need to be dried; Poly glue needs a little water to bond with the surfaces it is touching. Then DRY FIT the rock into place and look for the contact area on each rock. This means to place the rock into where you want it and look to see if you like it there. Pick up the rock and place a small dab of glue, for small rocks and a quarter size amount on the contact point for larger rocks. Place rock in it's proper position  and move to the next one. This method is great for the indoor permenant display but; it is very heavy when you are done. Also using Glue is only good for a short vertical height of less than approximately a foot (12") with the stone laid on top of its self without reinforcement.

Second, While at the Hardware or Big Box store go to the Outdoor Flower area and ask for "Rock Glue". It comes in a Squeeze Tube and is made for Rocks and outdoor projects having to do with Stone, Pavers or Concrete Blocks. Again, make sure your rocks are clean, dry and free of loose particles. This glue has a good shelf life and adheres very well. Also this is only good enough for short Vertical Heights up to about two (2') feet for flat rocks, less for round rocks.

Third, Temperature- Indoor you should have no problem with your glued joints lasting for a very long time. Outdoors- No glue likes Cold temperature, especially below zero and will deteriotate quicker in the Colder climates. But, do the work when it is warm and going to stay warm, not hot, because the glue will dry too quick and not cold, because the glue won't cure properly.

Fourth- Outdoors- If this is for a water feature area Definitely use a Mortar mix and still make sure the rocks are clean. To mix this in small amounts for a small area, 5 gallon bucket up to a wheelbarrow size, you can do this by hand easily. If you are going to do a large area at one time and you have two to three people to help, you may want to look at renting a mixer and letting one person do all the mixing while the other two are placing rock. It will go fairly quick this way and it will look great when you are done.   

I've been in the Constuction Industry for 35 years having lived in thirteen states in the East and now having an Outdoor layout here in Maine the weather is a challange and my construction experience is handy to fall back on.