OT--- Cement, Larry probably knows.

Have a tech question on cement. Here's the input data.

#1 Poured cement for the gate posts Sunday, 24" by 6'6" holes. I believe I used just over 2 yards to fill the 2 holes.

#2 The holes were wet, in fact 5' of water in them just before I poured. Ground water, not rain runoff. Pumped the water out, started pouring the cement. Bottom 3' of each hole, made a dry mix,,, just damp,,, cause there was water coming back in the holes. After I poured each wheel barrow in, mixed it as best i could with a long handled shovel.

#3 Used portand cement type II. Mixed by hand in a mixer, tried to stay a little rich on the mix.

#4 See the pictures, the gates and a pic from the block manurfacter gallery. There will be 68 of those block/stones dry stacked around each I beam, they are 41 lbs each, so 2,788 lbs sitting on or around each post.

THE QUESTION......... How long do I wait for the concrete to cure before I dare add these to complete the project?

Thanks for your help with this!! You'all are always in the know!

L.

Normal concrete (from a plant) is supposed to reach 75% strength at 7 days and "full" strength after 28 days. As long as you didn't over mix the damp stuff at the bottom of the hole, 7 days should be sufficient. Without some test cylinders it is hard to judge the strength of the concrete. One summer I tested concrete samples and they were breaking at 75% after 3 day, 100% at 7 days and 150% at 28 days.

I would stack the stone first, then let the weight of the gate on the structure.

When you say "Over mix"? Is that mix it too rich with cement? Or too wet?

Had a difficult time controling the water as you might imagine, but it looked good once the concrete soaked it all up.

Thanks for your help. Sounds like I better wait a couple weeks.

L.

Maybe im missing something but i dont see any adjustment for sag after yrs and ground settling ect.

I helped my brother (a welder by trade) hang some similar gates. He adjusted them by heating up the horizontal "hinge" area w/ his torch and slapping snow against one side or the other (top or bottom, depending on which side he wanted to contract) to bend it to where he wanted it. That might be one option if your posts shift a little.

Looks good!

Really nice work.. be sure and post the finished photos.. this part of the country we have to pour concrete in water hole a lot. I have never noticed any problems. Just give it 10 days or so and stack the blocks.

Engineers and OSHA require 28 days cure time before further construction of Walls or Steel structures." A lawyer thing" As far as I am concerned 10 Days works great. We have done it for years with no problems, on Residential and farm sites. The Acg.

What kind of dirt do you have? I have never seen orange dirt before. That is going to look nice when you finish. Stan

a week would be good, your gonna have some nice entrance to your property, it really looks great!!

3000 lbs sitting on a yard of concrete in those dimensions is nothing.

If the weather is warm, you could put that on the next day. In colder temps, an extra day for cure would be good, most of the concrete is insulated by the ground.

As with Larry and bjb, 7 days should about get you there. I would worry less on the stones you will be setting and more on the moment or tendency to tip the gates in. In my basic knowledge of these things, that would be putting a somewhat worse stress on the concrete. So keep the jacks under it for a good 7 days. The compression from that little bit of stone isn"t much to worry about.
And... nice looking project!

Thanks everyone! Glad you like them, it has been a fun project.

Hinges are ajustable in and out, and up and down. However the plan is not to have sag,,,,, I sure hope!!

I think you porvided great adivce,,, going to keep the jack in the center holding the weight till at least Sunday.

Thanks again!

L.

I'll take a slight technical detour on this one, for discussion sake, ( though I agree with the others give it 2 weeks or so, it should be fine to continue then ).

Now the technical part; what you mixed for the bottom, you probably don't really know what strength it is, based on what you describe, I would believe that the water cement ratio, when you put the dry mix in, would be hard to control, and this will determine actual or ultimate compressive strength. The rest of the way up, as you described, should be better, more uniform and or be close to your intended design mix strength, for this application, probably not much to worry about, but this would not be acceptable for say a footing, column or pier that is required to support a more substantial load, in that instance you really need to place all the material at once, it should be monolithic, no cold joints, free of voids etc.

I think in your situation, I would have preferred a short load or a batch truck that can provide smaller quantities of material, using a higher slump, placing same should have displaced the water in what was a trench pour, no forms I assume. As soon as the material was placed that water would come right up and out. Judging by your work, you may already know these things but just in case ....

On the residential high rise buildings,( reinforced concrete is a common design for those, structural steel for office and other occupancies, usually due to spans required ) we try to stick to a 3 day cycle, form, place, finish, move all the forms, repeat, building design allows for this so that the lower portions are capable of carrying the loads from the top.

Donald nnalert, developed a large area, midtown Manhattan, west side around 54th and the end of the Henry Hudson Parkway they were in there for years, driving piles and doing heavy civil work prior to all these concrete buildings going up. One of these buildings, while going up, around the 1/2 way mark, it was determined that the concrete did not meet the compressive strength required, they could continue to a certain floor, then had to stop, due to the load, corrective and remedial work was done to solve the problem, was probably a very costly solution, but shows that the this is a highly versatile material.

It's tested at 7 days obtains full strength at 28 days.So 7 days.

37, that is Good Ol' Carolina Clay soil. The upstate part of SC has plenty of it. The red color comes from some iron content.

28 days is the standard for curing it out to gain most of its strength