how strong is wood?
 

ok i spent enough time looking for an answer and i know one of you engineer has got to know the answer. so here goes:

my back porch had footers under the posts that weren't done correctly and heaved in the freezing ground. I've gotten them out of the ground but now i need to get them up into the bed of my lifted truck to dispose of them, they are awkward and weigh about 500 pounds each (3 of them). So if it will work i'm thinking about constructing a somewhat crude grantry crane at the end of my driveway that runs along the side of my house. there's 2 4x4 holes in a a slab of concrete where 2 fence posts used to be. they have a 9 foot on center span.

i'm pretty sure the 4x4 side posts are plenty strong and i will brace them 'torsionally, but how much weight will a 4x4 with a 9' span handle with a single chain hoist in the center? 4x6? (pressure treated pine btw)

sledgehammer is your friend, make those big ass chunks of concrete smaller and you'll be much better off I think.

lol, they are 16" in diameter and 30" long, i don't think i'll be breaking them

Got a friend with one of these? LOL

http://images02.olx.com/ui/1/79/52/1287752_1.jpg

Go to Sunbelt and rent a bobcat for $50/day. Not only will you be able to lift them into your truck, you will have a hell of a fun time doing it! I love renting machinery to do stuff at home. Last thing I rented was a ditch witch to run a 220V line to my garage for my future welder. So much cheaper to do all that yourself and then pay an electrician to tie it into the box.

Harbor Freight jackhammer?

Harbor Freight wet-saw?

dynomite?

rool them into the backyard and soak in some type of highly flammable liquid, it'll erode the strength of the concrete quickly (brake cleaner does wonders on concrete driveways) and then set them on fire? They might become brittle enough to break into pieces.

Hammer-drill 1/2" holes in them, drive a splitting spike in w/ an 8 lb sledge?

Nothing productive to add other than holy shit.

Don't ask Joe. He said you could lift your car with your roof trusses.:)
That's what happens when you ask an electronics engineer about structural strength.:)

Seriously, I work with a lot of demolition contractors and you can rent a two-stroke "cut-off saw" for a day for <$50 and make "safe to handle" sized pieces so you don't hurt yourself or your truck. It is not worth losing a foot or a tailgate over $50.
http://www.drillspot.com/pimages/3040/304022_300.jpg

BTW - Do you not own an engine hoist? Mine is rated for 2000#. I'd loan it to you if you were local.

Edit - I've never seen a Bobcat Skid-Steer Loader for less than $300 per day. Just cut-em up like the contractors do.

yeah these are no joke 500 pounds may even be a conservative guess on weight, they were't very fun getting out of the holes

yeah i know i can rent a demo saw but i don't much like using them, last time i had to cut a 200x3' in asphalt and the dust is insane. and no i don't have an engine hoist, i'd rather buy one than rent something else but i'm a broke new home owner and exploring my options....without hurting anyone or going to jail

Dig a hole, and bury them = FREE

Seriously, soak them in something, maybe kerosene, and just bash them with a sledge for an hour. You'll sleep like a baby that night... oh joy, what a reward!

what will kerosene actually do here? i'm thinking burst into flames when i hit a stone that will spark

yeah i have a 12x30' concrete porch i need to break up and redo also so i'll be getting my excercise don't worry lol..... which i also need to put in my truck and dispose of somewhere because i don't want to spend the money on renting a dumpster:fawk:

Bobcat is your friend....

Pick up those blocks in one swoop and put in your truck. Also can make destroying that porch cake also. You put the bucket underneath and lift up the slab a ft. Then hit it with a sledge to break off chunks. Rinse and repeat until its all broken up.

My dad was a landscaper before he passed away, and destroying and pouring concrete walkways was one of the many things he did for customers. This was how we did it. You could do full demolition of a walkway in a couple hours. You'll see that its the best way after you've read everyone else's replies. Its fast, simple, and relatively cheap.

sounds like you seriously need to invest in a bobcat for a day, should make easy work of busting up and loading those pieces of concrete. should be able to do all of it in not time provided you know how to operate one (or are a quick learner, not that they're hard to use considering i've been running them since I was ~12)

i'm not worried about the rest of the porch i'm pretty good with a sledge and i have time to get it done i just need to lift these large monolithic chunks into my truck then i will roll them out somewhere. i'm hesistant about a bobcat because i don't have permits and don't want to draw too much attention as i've already had a problem with my township

well i tell you what get the sledge and a chissle work the chissle in and then pound it with the sledge the shit will split easily into managable peices. Of course i would just pick em up and toss em into the truck but im not a pussy from PA :hustler: 500 lbs my ass i bet they arent much over 2 someone grab a scale.

if they were only 200 pounds they'd be gone by now. my research tells me concrete is 150 lbs/cubic foot. and i can tell you they are a bunch heavier than the fully dressed ka24de engine that me and my buddy carried which is supposed to be like 380.

Engineer chiming in:

Without working out the calculations for your proposed gantry here at work this morning all I can say is to break up the concrete. I know it sounds dirty, but you can do it easily and well.

Rent one of those big ass drills KPLAFIN posted, and drill holes 1/3 and 2/3 the way up each piece. Hit with sledge all the way around, and then use a very large lever to pry the pieces apart.

Concrete is very strong in compression, but weak in tension. It may not work, but it's better than trusting a 9'(!) wooden beam to lift something that weighs more than a dressed engine. I can already tell you anything that will have to lift this weight, and have a span wide enough to back a truck under had better be made of steel, or look like a friggin railroad tie.

I liked the bury them idea.
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