NY Bluestone

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Author Message Ed DiGiovanni (Unregistered Guest) Unregistered guest Posted on Saturday, April 24, 2010 - 07:19 pm:    I have a 15 year old stone terrace with New York bluestone as the decking. The stone are 2" thick and are laid in a bed of mortar over a 4" concrete slab. Every spring I have to repair the mortar joints that have popped and spallded loose. 5 years ago we removed all the mortar from the joints and repaced with a polymere modified mortar and then sealed with a solvent acrylic. My question, is there anything other than mortar that I can fill these stone joints with that will survive a michigan winter? It gets direct sun all summer and freezes solid in the winter. -Thanks,E.D. Tim Werbstein New member Username: justatim Post Number: 1 Registered: 04-2010 Posted on Monday, April 26, 2010 - 08:22 am:    I've sand-bedded stones that thick in freeze-thaw climates, allowing the bed to drain to the edges. Dale Roberts CSI, CCPR, CTC Senior Member Username: dale_roberts_csi Post Number: 77 Registered: 10-2005 Posted on Tuesday, April 27, 2010 - 12:08 am:    HI Ed, Did you include movement joints Per TCNA EJ171-09(soft joints every 8' to 12' in each direction) to allow for the expansion and contraction of the stone? is there any slope or drainage for the thaw (moisture to drain away from the stone), or does all the moisture soak into the stone during each freeze thaw? which i am told happens several time during the winter. this type of installaiton needs expansion joints and drainage. hope this helps Brian E. Trimble, CDT Senior Member Username: brian_e_trimble_cdt Post Number: 26 Registered: 08-2005 Posted on Wednesday, April 28, 2010 - 06:04 pm:    Any paving system that uses mortar is prone to maintenance issues over its lifetime. And the way you install the mortar (along with its makeup) will determine whether it lasts one winter or more. I like Tim's idea of using sand between the units. That way the only maintenance is sweeping more sand in the joints and not the labor intensive mortar repointing. You might consider a polymer sand (sand mixed with an additive that bonds the sand togehter). In any case, you want to keep the joints as thin as possible since thicker joints will deteriorate quicker. As I mentioned the installation of the mortar is critical. I have seen too many jobs where a dry sand cement mixture is swept into the joints and then wetted down. That almost assures maintenance every spring. Mortar should be installed like mortar in a wall, or at the least with tile setting techniques. And as Dale mentioned, make sure you have good slope because the water that sits around will cause a lot of problems. Richard Howard, AIA CSI CCS SCIP LEED-AP Senior Member Username: rick_howard Post Number: 234 Registered: 07-2003 Posted on Thursday, April 29, 2010 - 09:53 pm:    The Eisenhower Executive Office Building next door to the White House has bluestone paved walkways at the entrances that date back to the 1870s. They were installed with open joints on masonry pedestals. When the building was renovated in the 1990s, worn pavers were moved to less traveled areas or turned upside down. They should be good for another 100 years or more before they need any more attention. Ed DiGiovanni (Unregistered Guest) Unregistered guest Posted on Sunday, May 02, 2010 - 07:18 pm:    Dale, there are no movement joints installed. There is a 2" slope running 10'. It's properly flashed and caulked where the masonry meets the house. Brian I thought about removing the mortar and installing sand into the joints, I'm just concerned about water soaking into the mortar bed under the stone, freezing and popping the stone loose. I had someone suggest removing the mortar and filling the joints with closed cell backing rod and then filling with an elastomeric rubber mixed with sand and applied with a mortar grout bag, then dust some cement powder on top of the rubber while I'ts still wet. Not a bad Idea, I'm just not sure if I need to totaly remove all the mortar from the joints or if I could just grind them out about a quarter inch deep and then apply some sort of a rubber caulking product. Can anyone suggest a reliable caulking that will perform in this type of restoration? Also looking for the proper kind of sealer to apply to bluestone. I've been applying a solvent base acrylic but I'm thinking that maybe a siloxane sealer may perform better on this type of stone work. Thanks for all of your advice!---E.D. Dale Roberts CSI, CCPR, CTC Senior Member Username: dale_roberts_csi Post Number: 78 Registered: 10-2005 Posted on Tuesday, May 04, 2010 - 05:27 pm:    Do not look to sealers to solve this problem. Sealers are water repellants, not water proofers. Solvents and siloxane sealers are in the same family and not that much different. NY Bluestone is a hard dense stone. If you had a softer stone you see cracking and spalling of the stone. You want to look at adding soft joints for expansion and contraction of the stone and substrate. Or completely cover the stone with plastic in the winter and uncover in spring. If you do no put expansion joints in your building your building will put expansion joints where they want them. Sorry sometimes there are no easy answers.