I agree.. I usually don't bother returning the 5-10 bags I have left over
as even a year or two later they are fine for posts or small jobs around
the property. (Some of the two year old left overs from my tower base will
likely become supports for a "skywire" HO loop if I can get it in before
the ground freezes.) But If I had 20-30.. yeah, I would.
What always happens if you buy an exact amount is that you end up digging a
bigger hole than specified.. especially if dug with a shovel (like I did
for my tower). Then you don't (properly) take into account the bigger size
or the irregular shape gets you. The bigger hole is good... more is always
better.. but it throws off the bag calcs. Also I imagine over 80 bags a
small amount of waste per bag adds up, etc.
So I agree.. one other feasible plan is to have someone ready to run into
town and get 10-20 more bags based on where you are at when the hole is
1/2-3/4 the way full. I've done that before.. and even if the rest of the
concrete gets poured two hours later it's ok.
I'd also always count on double the sand and pea gravel for the bottom of
the concrete base of the tower and use it. I've seen too many tower bases
fail because they don't drain. Ultimately a pier pin is the best
configuration for a guyed tower.. but it doesn't work well if it's a
building bracket tower (like I ended putting up 1/2 the height of the
planned pier pinned/guyed tower... :O( )...
Good Luck.
Fred W0FMS
On Oct 13, 2010 12:09pm, Dan Schaaf <dan-schaaf@att.net> wrote:
> I have found that Home Depot takes back unused bags of Sakrete, just for
> future reference, so best to buy 30% more. However, both online and at
> the store, they can calculate exactly how much to buy based on the hole
> size.
> Definitely pin it with rebar and pour more before it sets up completely.
> Takes 30 days to set
> Dan Schaaf
> ==================================
> K3ZXL www.k3zxl.com
> Cape Cod Instruments www.gnm-inc.com
> NOBSKA www.nobska.net
> ==================================
> ----- Original Message ----- From: fred.spinner@gmail.com>
> To: towertalk@contesting.com>
> Sent: Wednesday, October 13, 2010 12:58 PM
> Subject: Re: [TowerTalk] Ran Short of Concrete
> I'd consider drilling in about four pins into the concrete (or anchors of
> some sort, rebar with epoxy, expansion, etc) and then pinning the top
> section to the already poured section. I think in a yard or so of concrete
> that this is a fairly adequate way of making the two blocks solid with
> each
> other. Typically when one wants to connect sections of concrete together
> you want them mecahnically pinned to each other.
> I also agree that dirt around the tower legs is asking for corrosion
> problems. It is too bad that you didn't get more bags before the concrete
> was completely cured, you can add concrete to "semi-cured" concrete to
> cure
> in progression. Once it's white and solid, it's too late for that though,
> I think you likely have enough weight to hold the tower up as it is. You
> do
> want to keep water off the legs and make sure that smaller section of
> concrete doesn't break up. I'd suggest rebar in it like it was a driveway
> (since it's going to be literally a driveway/sidewalk like slab)...If you
> are 6" below grade, I'd suggest 8" more of concrete taperd off for water
> runoff.
> Good luck with it.
> Fred W0FMS
> On Oct 12, 2010 9:28pm, "Roger (K8RI)" K8RI-on-TowerTalk@tm.net> wrote:
> On 10/12/2010 11:42 AM, Steve Bagley wrote:
> > Hello All,
> >
> > Another concrete question... I mixed 45 80lb bags yesterday (electric
> > mixer) and still ran short! My guess is that I have one cubic yard in
> the
> > ground with the tower base in it. I am about 6 inches below grade.
> >
> > Thoughts on how to rectify this? Add more concrete on top? Fill the top
> > with gravel for drainage? Fill the top with topsoil?
> There are a couple of important points:
> What is the soil like?
> If the soil is sandy or solid then the amount of concrete is not
> terribly important. It serves two functions. To keep the tower from
> sinking, or the base from moving sideways. I've put many a tribander up
> at 50 feet with just a "dirt base" for the guyed tower.
> The worrisome part is the top of the concrete being below grade. IF you
> don't live in a arid location, the tower legs at the surface of the
> concrete is a prime location for rust. You do not want the surface of
> the concrete where the tower legs enter to be below grade if water or
> even moisture can collect there.
> If not in an arid location the top of the concrete needs/must be "above
> grade"
> Also you can't normally just pour fresh concrete on top of cured
> concrete and expect a complete bond and seal. IOW it leaves a seam for
> water to get to the tower legs and creates a weak spot. After a few
> years I've seen the legs separate as neatly as if they were sawn off.
> There are several brands of concrete "patch" that will bond to cured
> concrete and are meant for resurfacing driveways. This stuff will become
> part of the underlying concrete even if it's only a quarter inch thick.
> I'd get a bag of this stuff, make sure the top of the tower base is
> clean and then mix up a bag and pour it on. Then pour the rest of the
> concrete to get the top of the base above grade. The reason for not
> adding more "patch" is the stuff is around $26 USD per bag.
> IOW clear out the dirt, put in a form so the top will be at least 4 to
> 6" above grade, do the patch and then the pour. Talk with the people
> who sell the patch material and follow the guidelines for the patch and
> pour.
> I'd certainly seek out the advise of some one who works with this stuff.
> 73 and good luck,
> Roger (K8RI)
> > My son worked his butt off helping me! Any ideas would be greatly
> > appreciated.
> >
> > Tower is going to be an Ameritower, 50 foot with a Mosley TA-33. Guyed,
> of
> > course.
> >
> > Steve, N2MAI
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|