Just a dumb question here.

Why can't they put the dry mix in the truck and when they get to the sight add the water? That way it is fresh every time.

Do I since a business idea kicking in?

 

When they do it at the plant how is it done?

Do they put liquid concrete into the truck premixed and the truck just delivers it?

Or do they put the dry mix into the truck and add the specific amount of water and then the truck mixes it up?

If it is the second why can't they just do that on site? Have two water supplies on the truck. One that is specific to the perfect mix and another to add if necessary.

That way you don't ever have to worry. The driver could always shoot the water into the mix a mile before he got there to assure it was ready to go as soon as they arrived.

No more hot loads.

 

...Your idea is brilliant but someone already did that and it's called mobile mix...and it's awesome...

 

Just talking out of my hat with no real knowledge, maybe it takes a bit more water than is feasible for a truck to carry with a full load. Ready-mix does cost more, probably because of smaller capacity among other factors.

 

Water doesn't shrink when you add it to concrete...nor does concrete...

 

Stop it.

I want the cheap price.

 

Have you priced it out? I've never build any sky scrapers but the price is very competitive.

 

You hear that a lot do you?.....:whistling:laughing: :laughing: :laughing:

 

Way too much.......:sad:

 

Today my concrete driver got a flat tire on the way to my job with 10 yards of mud it was on the road for about 1 to 2 hours before we poured it out. What's the rule on that any concrete guys out there care to help. Thanks here's some pics. The driver felt it and it wasn't warm, if it matters

You need a thermometer that has at least 3" of concrete cover in all directions left in the concrete for 2 - 5 minutes. Most specs. around here only concrete temp. up to 90 deg. If there are no specs. which is usually the case with residential concrete then like Greg 24K said & use ASTM C-94. I would be more concerned with how long it was mixing & what the driver did ,so it did not set up on him.

 

If it doesn't crack/delaminate/spall/ or fall apart within the first 7 days then you'll be fine. Almost all structural issues pop up within 7 days. Any cracks after that are from shrinkage, which doesn't effect strength. Assuming the soil below is stable and rebar/WWR placement is correct of course.

The biggest concern with a hot load is not getting it consolidated. If it's still fluid enough to come out the shoot and responds to a vibrator, it's probably ok. Unless they add a sh!t ton of water then it'll delaminate and basically fall apart slowly because the compressive strength got compromised. By the looks of the footprints in your pics, it looks like it was still a good.

 

It was poured Monday and alls well so far, I think we got through it ok.

 

The problem with those type of trucks is they mix by the volumetric method & if they are not maintained properly ,which most aren't , the concrete they produce is junk. THey are generally used around here for non-structural jobs that require less then min. truck load charge.

Not arguing but how do you know this? True I'd be a little suspicious as to how well they do their quality control from the back of a truck as opposed to the batch plant. But what have you seen or tested to tell you the concrete is junk?

 

We test everything we pour. From the times we have used volumetric trucks they are not giving you what you ordered. The biggest problem is their unit weight is usually off. Which means their mix proporations are wrong. If the mixer is maintained they mix well, but most aren't, because nobody is testing their concrete.

 

It was poured Monday and alls well so far, I think we got through it ok.

Probably, but I've seen concrete fail months or years after a pour. All due to bad concrete from the beginning.

 

I don't think two hours was long enough for that to be a problem

 

I don't think two hours was long enough for that to be a problem

You're right. Personally, if it was any longer than that, if it was 2 hours 15 minutes, I would send it back. I would say send me a new load, not buying old concrete.

 

You can test the concrete just like when you order a transit mixer.:whistling

Yeah I know, I was wondering if anyone has ever done this. Being that it seems they are used strictly of residential work where special inspection is rarely required.

 

I was on a job once were a concrete truck that was lost didn't show up till two hours after it was batched. This was a like a twenty truck'r pump. Anyway those idiots spent all night around the clock chipping that wall out. But that was for some Redmond giant that was going to be paying for a hacked building.

You have a slab on grade I assume and not a suspended deck. You should be fine.

 

A story that may be of interest reading these posts reminds me of what happened to a relative. They put in cement sidewalks around their house poured by two different trucks. Same people prepping site poured same day same people working / finishing cement only thing different was concrete two different batches.

You could not tell there was anything different where one truck stopped and the other started the rest of the summer. Come winter they buy cement sidewalk safe safety salt don’t know what chemicals are involved in that. Where the fist truck poured and precast cement steps where untouched. Well the second truck like you drew a line completely ate away and striped the surface off to just looks like ruff exposed aggregate no finish.

Every other respect as far as you can tell its fine. First part and precast steps fine something was screwed up with the second load what I don’t know I was not there.

 

It's all about the water. If the amount of water added to the batch in order to keep it usable exceeded the mix design's w/c ratio then it won't produce the specified mix - period. If there's too much water then you didn't install the specified mix.

Viscosity ?

 

Send it back

Blaa Blaaa Blaa

water , ratio, 4500lbs, viscocity, greg 24k is correct again

300 turns of the drum or 1.5 hrs

if they have exceeded those astm specifications send it back ESPECIALLY ON A REQUIRED 4500LB MIX

 

Itz been a month and no sign of problems

 

It was 2 hours i think it will be just fine

 

Blaa Blaaa Blaa

water , ratio, 4500lbs, viscocity, greg 24k is correct again

300 turns of the drum or 1.5 hrs

if they have exceeded those astm specifications send it back ESPECIALLY ON A REQUIRED 4500LB MIX

Besides, there is Already a building on it so it would be very difficult to send back now.

 

Besides, there is Already a building on it so it would be very difficult to send back now.

That's right, the sooner you cubber up de evidence de better...:jester:

 

Evidence of what? Mud was 2 hours old ?
What do you suppose is going to happen?
I got info from a special inspector that doesn't seem to be too concerned about it. As a matter of fact he said 4500 psi isn't for the load, it for the acidic soil and the 4500 is needed for its density. But the slab has 4 inches of sand and plastic so the concrete isn't even contacting the soil. The footings were poured with the first truck that had no problems.

 

I don't think ANYTHING bad is gonna happen. In fact, I thought all of this was much ado about nothing.

Here we are, still talking about drum turns & water ratios and the durned building is nearly done!
:laughing::laughing::laughing:

 

Someone brought this post back from the dead, and I was moving forward, now I'm going to trip on it again.

 

Lots of things that go on that we have no control over, like non of us get to see them actually mix it. Other things we can't control is the weather. But your right Griz, many factors when it comes to concrete, most of those factors are above my pay grade. ( like engineering )However, I try to keep up the quality on the things I can control.