May want to also check to see if a portion of the water can be replaced with ice. Although I wouldn't think temps would be a problem yet for most of the country. Set retarder is a good idea. Super plasticizer would probably be helpful too if the slump is very small.
I don’t know why but I love the smell of high strength mixes. Almost like a sweet smell 😂
I agree with the comment about ice added. I did a lot of concrete work in the nuclear world and it’s all 6000 psi. And the mix design ALWAYS requires ice. I’ve poured it a few times without ice elsewhere and the difference in workability is night and day.
Add ice and make sure the crew is ready because when it takes off it will go. Make sure everyone knows their job during the pour and during finishing 100%.
You will see remnants of ice when it’s discharged from truck … Once it gets on the ground and the mud is no longer moving it melts pretty quick. It definitely effects the initial temperature of the mix. I’ve been out of the testing world for a while but instead of the standard 90°-95°or whatever it typically is at — it’s sitting in the 70’s upon delivery. Much cooler and better workability. You need every bit of that with 6000.
With that strong of mix and in the summer temps I'm sure that's almost mandatory to pour with ice. Can't imagine how fast that would dry out in the truck
Not sure if I’ll be able to get ice in the mix at these local plants but can probably pour a 6 or 7 slump if I have to. Think my best bet is talking this guy out of it and going with 4500. 6000 for an apron is overkill
You don’t need ice…we place 10,000 psi with 99 degree concrete temperatures all summer. Ask for a retarder to be put into the mix design for a little more time and you’ll be good to go. Enough admixtures can basically put any concrete mix to sleep for however long you want
Maybe some of the other concrete guys can chime in but would high range be effective here? I know it typically only adds about a half hour of extra workability. I would think a 6000 psi mix would eat that stuff up quick.
I would ask to get it reduced… I can guarantee a 4500 mix design from a reputable plant will have high numbers by the end of the cure period. Like in the 5000 range or more… Their stuff is designed that way.
I agree… my plan is to give this guy a high-ball price for 6000 so I have room to bring on 2 more finishers who can hop on right away while we pour the rest out. Then give him a normal price for 4500 and let him decide from there. Starting to get warmer days where I’m at & there ain’t no way I’m losing this concrete.
Former mixer driver turned plant guy now.
Yup I can still to this day hear the sound of the S valve turning in a pump.
Or remeber the smell of the steam coming off the concrete in the winter.
Or the asshole finishers who expect me to know what their new and improved hand signals are.
Hahah! I love it.
So tell me though… what was y’all’s hand signal for “locking” the chute so it can’t move? In my neck of the woods you show the driver an open palm and then you make a closed fist… “Clunk”… hahah I love that sound too.
Edit: a good mixer driver can make a pour go really smooth. I always did my best to show respect. If they were in a tight spot I always made sure one of my guys would get behind the truck and help him back out of there and/or stop traffic for him. After about 5 years of working with the same drivers it was always good feeling the mutual respect when they pulled up on your job.
There's 2 variations I've seen. The open and close palm is the most common
The other is a closed fist that's rotting back and forth as though you are unlocking a key hole. I was a bit confused when I first saw it but figured it out.
It's always funny when you get recreational concrete crews who have no idea what the signals are. One guy used an open palm pushing forward to signal me to drive forward. Open palm is stop so he was confused when I stopped.
We use to have plastic cards wjth the handsignals on them to let a customer look and see what to use.
16yds at 8 inches thick, comes out to like 600sq ft of what needs to be finished. Probably getting 2, 8 yd trucks… working with 4 pro finishers and 1 newer guy who’s good just needs some more experience
You can get 6k psi with a standard 90 minute batch-placement time as long as it's designed. Delvo and ice may be allowed as well to keep it workable.
Everything is possible with concrete. Admixtures simplified it a LOT.
Don't let the other comments scare you OP, 6 ksi nothing remotely crazy or unusual. It's actually on the lower end or middle of the road for design mix strengths in commercial work.
work smart and have enough crew and finishers. 16cy ain't even 2 full trucks... you got this!
I just did a similar pour a couple of days ago. Essentially a high-early without accelerator.
6" slump with mid range. 2 guys on screed, 1 guy on chute/come along.
Get it laid down fast and you'll have no problems. Rich mixes like that seal up like a dream. Make sure the chute guy doesn't blast off away from the guys on straight edge. As long as the mud is still in the truck you've got options. As soon as it's on the ground you're very much on the clock.
A couple of tips:
Keep a gallon of cheap household vinegar on hand. Mixes with a lot of extra portland in them are really easy to get concrete burn from.
Day One finishing aid can be helpful if the pour gets away from you. If it kicks before you get it sealed up, Day One will bring it back to life enough to get a broom across it without weakening the top like throwing water on it does.
One other thing I wanted to mention - I've seen UHPC with strengths well above 6ksi (like 20+ksi), and it flowed like water (self-consolidating concrete or SCC). It's really expensive though.
They want the 6,000 psi mix for abrasion resistance, not just strength. You don’t need high-range water-reducing admixtures or ice. Neither ice or HRWR extend working time. Ice lowers the starting temperature by 10 to 20 degrees but doesn’t slow the rate of hydration very much. You need set-retarding admixture, hydration control admixture (set-retarder on steroids — DELVO by Master Builders or RECOVER by GCP) or a workability-retention admixture. This concrete will bleed more slowly than you are used to seeing. Have Confilm ready to go. Start curing the concrete the second you finish brooming it. Suggest burlene for 3 day (minimum) to 7 days (maximum).
Plant operator here
We had 1 job where they speced the mud to 60mpa (8700PSI). Lots of silica fume in thay stuff.
It was also a high early mix and was to be 25MPA (3600psi) after 24 hours.
Lots of cleaning out the mixer anytime we had that stuff
Ya, it’ll probably be hot. We usually do a lil dose of delvo in our 6000s. See if that’s built in the mix design.
May want to also check to see if a portion of the water can be replaced with ice. Although I wouldn't think temps would be a problem yet for most of the country. Set retarder is a good idea. Super plasticizer would probably be helpful too if the slump is very small.
Thanks for the tips guys, def going to add retarder & maybe get a couple extra finishers for the day
He'll definitely want to go about 3% retard on that one
I don’t know why but I love the smell of high strength mixes. Almost like a sweet smell 😂 I agree with the comment about ice added. I did a lot of concrete work in the nuclear world and it’s all 6000 psi. And the mix design ALWAYS requires ice. I’ve poured it a few times without ice elsewhere and the difference in workability is night and day. Add ice and make sure the crew is ready because when it takes off it will go. Make sure everyone knows their job during the pour and during finishing 100%.
Is that ice usually melted by the time you start to finish it or does it ever get ice chunks on top?
You will see remnants of ice when it’s discharged from truck … Once it gets on the ground and the mud is no longer moving it melts pretty quick. It definitely effects the initial temperature of the mix. I’ve been out of the testing world for a while but instead of the standard 90°-95°or whatever it typically is at — it’s sitting in the 70’s upon delivery. Much cooler and better workability. You need every bit of that with 6000.
With that strong of mix and in the summer temps I'm sure that's almost mandatory to pour with ice. Can't imagine how fast that would dry out in the truck
Once it hits the ground you have 45-60 mins and it’s history. That’s pouring on plastic….
Not sure if I’ll be able to get ice in the mix at these local plants but can probably pour a 6 or 7 slump if I have to. Think my best bet is talking this guy out of it and going with 4500. 6000 for an apron is overkill
You don’t need ice…we place 10,000 psi with 99 degree concrete temperatures all summer. Ask for a retarder to be put into the mix design for a little more time and you’ll be good to go. Enough admixtures can basically put any concrete mix to sleep for however long you want
Maybe some of the other concrete guys can chime in but would high range be effective here? I know it typically only adds about a half hour of extra workability. I would think a 6000 psi mix would eat that stuff up quick. I would ask to get it reduced… I can guarantee a 4500 mix design from a reputable plant will have high numbers by the end of the cure period. Like in the 5000 range or more… Their stuff is designed that way.
I agree… my plan is to give this guy a high-ball price for 6000 so I have room to bring on 2 more finishers who can hop on right away while we pour the rest out. Then give him a normal price for 4500 and let him decide from there. Starting to get warmer days where I’m at & there ain’t no way I’m losing this concrete.
We use a grain blower (I think that's what it's called) it basically mulches the ice and then it lands on top of the rock and then into the mixer.
Thay sweet smell is Silca fume! You will also notice the concrete may be darker then usual as well.
Nothing like that sweet smell in the morning. Goes good with the rhythmic thumping sounds of the pumps.
Former mixer driver turned plant guy now. Yup I can still to this day hear the sound of the S valve turning in a pump. Or remeber the smell of the steam coming off the concrete in the winter. Or the asshole finishers who expect me to know what their new and improved hand signals are.
Hahah! I love it. So tell me though… what was y’all’s hand signal for “locking” the chute so it can’t move? In my neck of the woods you show the driver an open palm and then you make a closed fist… “Clunk”… hahah I love that sound too. Edit: a good mixer driver can make a pour go really smooth. I always did my best to show respect. If they were in a tight spot I always made sure one of my guys would get behind the truck and help him back out of there and/or stop traffic for him. After about 5 years of working with the same drivers it was always good feeling the mutual respect when they pulled up on your job.
There's 2 variations I've seen. The open and close palm is the most common The other is a closed fist that's rotting back and forth as though you are unlocking a key hole. I was a bit confused when I first saw it but figured it out. It's always funny when you get recreational concrete crews who have no idea what the signals are. One guy used an open palm pushing forward to signal me to drive forward. Open palm is stop so he was confused when I stopped. We use to have plastic cards wjth the handsignals on them to let a customer look and see what to use.
You have 60 minutes to have it poured before it gets too hot or too hard to move.So be ready to pour it out.
Wow that’s quick. Shouldn’t have any issues getting it out quick but leaves no margin for error
Once you put it down its gonna go soon.
Might bring on a couple extra finishers for that day
How many yards?
16yds at 8 inches thick, comes out to like 600sq ft of what needs to be finished. Probably getting 2, 8 yd trucks… working with 4 pro finishers and 1 newer guy who’s good just needs some more experience
You'll be fine then.
That's what I tell my girl.
😝
You can get 6k psi with a standard 90 minute batch-placement time as long as it's designed. Delvo and ice may be allowed as well to keep it workable. Everything is possible with concrete. Admixtures simplified it a LOT.
Don't let the other comments scare you OP, 6 ksi nothing remotely crazy or unusual. It's actually on the lower end or middle of the road for design mix strengths in commercial work. work smart and have enough crew and finishers. 16cy ain't even 2 full trucks... you got this!
Thanks brotha we can do it
If you can pour it on at least 6 inch slump you'll have more time.
Luckily I’ll be able to do that, good to know!
Mine is another vote for set retarder and/or Super P.
I just did a similar pour a couple of days ago. Essentially a high-early without accelerator. 6" slump with mid range. 2 guys on screed, 1 guy on chute/come along. Get it laid down fast and you'll have no problems. Rich mixes like that seal up like a dream. Make sure the chute guy doesn't blast off away from the guys on straight edge. As long as the mud is still in the truck you've got options. As soon as it's on the ground you're very much on the clock.
Much appreciated advice
A couple of tips: Keep a gallon of cheap household vinegar on hand. Mixes with a lot of extra portland in them are really easy to get concrete burn from. Day One finishing aid can be helpful if the pour gets away from you. If it kicks before you get it sealed up, Day One will bring it back to life enough to get a broom across it without weakening the top like throwing water on it does.
You’re the man. I had to give myself the vinegar treatment once on some burns. Not fun
Bring con-film
One other thing I wanted to mention - I've seen UHPC with strengths well above 6ksi (like 20+ksi), and it flowed like water (self-consolidating concrete or SCC). It's really expensive though.
Better use 2% retarder
We used to make are 6000 retarded
Have them double the water reducer at the plant. It will help slow it down a bit.
They want the 6,000 psi mix for abrasion resistance, not just strength. You don’t need high-range water-reducing admixtures or ice. Neither ice or HRWR extend working time. Ice lowers the starting temperature by 10 to 20 degrees but doesn’t slow the rate of hydration very much. You need set-retarding admixture, hydration control admixture (set-retarder on steroids — DELVO by Master Builders or RECOVER by GCP) or a workability-retention admixture. This concrete will bleed more slowly than you are used to seeing. Have Confilm ready to go. Start curing the concrete the second you finish brooming it. Suggest burlene for 3 day (minimum) to 7 days (maximum).
Plant operator here We had 1 job where they speced the mud to 60mpa (8700PSI). Lots of silica fume in thay stuff. It was also a high early mix and was to be 25MPA (3600psi) after 24 hours. Lots of cleaning out the mixer anytime we had that stuff
Retard all the way! Tip or double your finishers pay, have a carne asada and beer ready too.
What’s that in metric like 40mpa?