Replies

1. 
   OneofmanyBobs | May 10, 2004 06:55pm | #1

   Concrete is nowhere near full strength in 7 days.  More like 30 days, depending.  Wedge anchors put a lot of pressure and can crack even cured concrete.  That's why people use J bolts.   Wait as long as you can stand.

1. 
   jpainter | May 10, 2004 08:21pm | #2

   Hmm.  Not the answer I was hoping for.  I know 28 days is for full strength, but I was hoping that a few days would be enough for the wedge-alls. I couldn't use J-bolts because I couldn't find them in stainless for use with my ACQ lumber.  The wedge-alls I was able to get in stainless. Maybe I should have re-thought that.  I think tomorrow when I pour the concrete I may pour a test bed on the side that I can use to try the wedge-all after a couple days.

   J Painter 

2. 
   RalphWicklund | May 10, 2004 08:21pm | #3

   What Bob said.

   Consider also that wedge anchors leave a hole that may be subject to water intrusion and if you live/build in an area subject to freeze/thaw cycles you could introduce further stresses beyond the mechanical of the wedge anchor.

   Using an epoxy anchor method might be a better alternative since the hole is filled. Look up the specs on withdrawal resistance for the comparisons.

   I have heard of a case where steel j-bolts have been straightened by extreme forces and pulled right out of the pour while epoxied anchors stayed put.

   I use Hilti products but Simpson and others have them, too.

1. 
   Frankie | May 10, 2004 08:45pm | #4

   Concider what RW stated. I have used the Hilti 2 part epoxy. You can get them for use with a gun (Cha-Ching) or in diposable cartidges. Drill hole, blow it out to remove dust, fill 3/4 with epoxy and drop in your rod - threaded rod that is.

   Doesn't get any easier than that.

   F.

1. 
   jpainter | May 10, 2004 09:02pm | #5

   Yes, epoxy is an option if I can find stainless rod.  I hesitate to use galvanized rod with all that copper from the joists, beams and posts dripping right down to the footing.  Guess I'll see how far I get with the rest of the framing first, and then make the decision when I have no choice but to set the posts on the bases.

   J Painter

1. 
   RalphWicklund | May 10, 2004 09:54pm | #6

   Stainless threaded rod is usually readily available, just not at Home Depot or Lowe's. My metals supplier stocks it in 12' lengths. How's $22.50 ea. for 1/2" dia. sound to you?

   I don't think there have been any tests run on materials as affected by ordinary runoff, just constant contact as in nails, screws, bolts and various hangers. One of the parameters I'm hearing is that fastners will have to stand up to the salt spray/heat/contact testing for 1,000 hours to be considered A-ok.

   I know that builders all over have been using stainless screws for decks with super results but not everyone goes the extra mile for longevity. Here, many are complaining about the cost of doing business and having to change from galvanized to stainless as well as complaining about the waste from stripped heads. Guess no one told them stainless was a softer material and maybe predrilling would help.<G>

1. 
   WorkshopJon | May 11, 2004 06:29pm | #13

   "Stainless threaded rod is usually readily available, just not at Home Depot or Lowe's. My metals supplier stocks it in 12' lengths. How's $22.50 ea. for 1/2" dia. sound to you?"

   Ralph,

   That is in fact a good price for SS rod.  For those of you who need a source for SMALL quantities of almost any non-super-specialty metal,   I've had real good luck with Online metals.

   http://www.onlinemetals.com

   Usual get what I need in 2 days shipped ground.

   Jon

   BTW, I did start putting those tiles up (not done yet as I have 3 areas, but the match is real good.  Thanks again.

2. 
   AndyEngel | May 11, 2004 03:33am | #11

   Can you put 'em in now, and tighten 'em up in a couple of weeks?

   AndyArguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it.

1. 
   jpainter | May 11, 2004 05:01pm | #12

   Lots of good ideas here... I'm pouring today at 4:30.  The truck will bring a 3000psi mix.  These are 12 inch tubes with post anchors in the middle, so I think what I'm going to do is wait a couple of days while I'm setting the ledger and the post heights, sorting lumber, etc. Then I'll drill for the wedge alls and just tap them in without cranking down the nuts.  Since I'm using six inch posts on top of the simpson bases, it looks like there is enough room to get a wrench in there later to fully tighten the nuts.  Half of the posts are for the second tier which I won't get to until later anyway.  This way I can continue to work but I won't risk wrecking the green concrete.  Thanks for all the ideas!

   J. Painter

3. 
   IanDG | May 10, 2004 11:36pm | #7

   At 7 days, with temperatures above 40F, the concrete should have reached about 75% of its final compressive strength.

   IanDG

1. 
   OneofmanyBobs | May 11, 2004 01:44am | #10

   Not always.  the 28 days is only a standard for testing.  Under "normal" conditions you get 70% of the 28-day strength after 7 days.  Concrete continues to harden for years.  3000 PSI concrete reaches that compressive strength at 28 days under ideal conditions.  It can top out much higher than that after months or years.  Too much water and the concrete may be only half as strong as its supposed to be.  A really cheap bag mix may only be 2000 PSI to begin with.  Add too much water like most people do, and its only 1000 PSI.  At 7 days if its kept damp you might hit 700 PSI.  Cure at less than 50 degrees or let it dry out, could be much less.  On the other hand, high-early-strength concrete properly mixed and cured could be 3000 PSI in a week.  That's compressive strength.  Tensile is only about a tenth of that.  So, cheap concrete may only be 70 PSI tensile after a week.  I sure wouldn't put expansion anchors into that. 

   Too many variables and a lot of possibilities.  The epoxy anchors are a good idea.

4. 
   SamT | May 11, 2004 01:03am | #8

   Using 1/2" jbolts, drill 3/4" holes in the ACQ. Drop a 1 3/8 length of 1/2" PVC over the j bolt. The PVC will isolate the bolt from the wood. Then all you will need are SS washers.

   If my thinking is messed up, someone please jump on me. . . I meant, jump in here and set US straight.

   I admit nothing. Nothing, I tell you.

   SamT

   Arguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it. Andy Engel

1. 
   moltenmetal | May 11, 2004 07:34pm | #14

   Just fine except 1/2" pipe is 0.84" OD, so you'll need to drill a 7/8" hole (27/32" if you've got the bit, but who's that fussy?).  Then you'll need a big, thick stainless washer to handle all that extra span, because you want the washer bearing on some wood NOT on the PVC sleeve.  If you do this, presumably the ACQ will stay in the wood and not rot away your (hot dip galvanized) fasteners.  You will have a bit of a galvanic couple, but with stainless steel being the noble material and the parts not being continuously immersed it shouldn't be such a big deal in practice.

   I personally like the stainless threaded rod and epoxy method, especially with the original poster's hurry.   Big advantage is that just like with the wedge anchors, you can drill the holes with the plate in place- no measuring, no slotting holes when you screw up the measurements etc.  Commercial 18-8 stainless (roughly equivalent to grade 304) is good enough, and 18-8 fasteners aren't all that expensive if you buy them from the right places.  Threaded rod is pretty cheap too.  One more piece of advice, though- put a dab of grease or anti-sieze paste onto the nut or threaded rod before you tighten it down, unless you never want to get it apart again.  In our experience, stainless steel fasteners "gall" (i.e weld together in spots under pressure) really easily, and we've had to split lots of nuts to get them off of bolts or studs, especially if somebody got a little too ambitious when tightening them.

5. 
   mike4244 | May 11, 2004 01:39am | #9

   If the anchors are not to close to the perimeter you can drill and install them the next day. I'm assuming the wedge anchors are for post connectors, if so the bolts will be approximately 3 or 4 inches from the perimeter. You won't break the concrete.

   mike