Teach Me About Slump Meters

[Mort]

This may sound like a dumb rookie question, and it probably is. I don't have a slump meter on my ancient truck, and the one in my trainer's truck was broken. So how do you use the damn things?

Here is what I know (correct me if I'm wrong):

- Doesn't work accurately with less than 5 yards
- Different for pea gravel / 3/4 rock
- Drum must be all the way wound up to read accurately

So what would, say, a 4" slump on a 3/4 rock mix read? And is there a "cheat sheet" somewhere that I could look at?

Thanks in advance.

[gant]

your truck doesnt have a slump gauge??

if you have less than 4 yards its not accurate and it does read different for different types of rock.. and the drum has to be in full charge but at idle is where mine is the easiest to read...

and a 4" slump on 3/4" rock should read 1200 at idle and 1800 at full throttle...

my slump gauge reads a little differnt than everyone elses at my plant, mine only had one on it from the factory and someone tapped into the line and put another one on it so a 4" slump on mine is around 1500..

if I have a torpedo load or pea gravel it always reads wetter than it really is.. and grout shouldnt really register on there more than maybe 500


oh and I'm just a dumb rookie too so I might not be 100% correct

[Ideal Driver]

I would say your pretty close gant. I have drove nine different trucks withing the past year. Each truck is different. They are all pretty close though, just a lil bit off from each other.

I'm a rookie to.

[Mort]

Thanks guys. Yeah, the truck is so old and crappy that it doesn't have one, hand controls for everything.

Gant, the Minnesota Chapter President on FTW is the paint manager at McNeilus, and he said he couldn't believe a truck as old as mine was still on the road. Hopefully, now that we're Cemex, it'll get shown to the scrap heap, since they allegedly don't run trucks that are over 10 years old.

[gant]

we've got a few old ones like that up at our city plants.. actually alot of them.. but those guys like to B!tch and complain and dont like to work, so we get most of the new trucks.. Hell I was only with the company for 6 months and I got a "new" truck..well its an 04 so its new to me.. but I never really had to drive junk.. my first truck I had was a 97 l9000 ford.. had some rust on it, but I got it cleaned back up and it was a damn good truck.. after I got out of it it went to hell again..

[lafargeslave]

we are trained to read ours with the drum at a slow turn. a 57 stone mix with a good 6,7,8 inch slump will read about 1000, or a tad lower. when charged up adding water to get to a 7" slump we watch the guage till it reads about 1500 1700. mixes with 89 stone and lots of chemicalls will read drier than they really are. Agilia which is considered a 26 to 30 inch slump (pancake diameter) will read almost zero on the guage. ours work unless you have a yard or less on. a 4" slump might read around 2000. all trucks and mixes probably read differently.

[gant]

^^^ you lost me lol

[BillyCement]

WTF? I am down with you Gant. I ain't no rocket scientist.

[cfconcrete]

What did he just say?

[Mort]

lafargeslave said:

we are trained to read ours with the drum at a slow turn. a 57 stone mix with a good 6,7,8 inch slump will read about 1000, or a tad lower. when charged up adding water to get to a 7" slump we watch the guage till it reads about 1500 1700. mixes with 89 stone and lots of chemicalls will read drier than they really are. Agilia which is considered a 26 to 30 inch slump (pancake diameter) will read almost zero on the guage. ours work unless you have a yard or less on. a 4" slump might read around 2000. all trucks and mixes probably read differently.

26-30 inch slump? From a 12 inch slump cone? How does that work...?

[concretejoe]

mort said:

lafargeslave said:

we are trained to read ours with the drum at a slow turn. a 57 stone mix with a good 6,7,8 inch slump will read about 1000, or a tad lower. when charged up adding water to get to a 7" slump we watch the guage till it reads about 1500 1700. mixes with 89 stone and lots of chemicalls will read drier than they really are. Agilia which is considered a 26 to 30 inch slump (pancake diameter) will read almost zero on the guage. ours work unless you have a yard or less on. a 4" slump might read around 2000. all trucks and mixes probably read differently.

26-30 inch slump? From a 12 inch slump cone? How does that work...?

He's more than likely talking about self-consolidating conrete. It is measured by measuring the spread. The test is about the same you just measure the diameter of the spread you get when you lift the cone.

[concretejoe]

My advice as far as your meter is concerned is to gauge it with a 10 yard load that is tested at the yard. After you give your qc guy a sample ask for the results. If your meter was reading say 1200 and they slumped you at a 4 then that would be your mark for that mix. Drier concrete will read higher. Weter concrete will read lower. Different mixes, different aggregates and different load sizes will read differently also. Long story short. Don't trust the meter. Use it as a guide. Nothing beats actual visual inspection of the load.

[lafargeslave]

yeah it makes a pancake 26 to 30 inches across.

[Mixer Driver 69]

Rookie here.

I've learned that slump meter + eyeball + my ear (as in how the mix sounds in my drum when in full charge or wound up) = slump.

Concrete is not an exact science. Lots of variables. After awhile, ya just get a feel for it.

Hope that helps.

[acbulldog]

My truck with a 8, 9, or 10 yard load of ¾ rock at full charge reads about the same: 2=2000,3=1700, 4=1500 5=1350 and a 6=1200 hope this helps

[Yard Bird]

A slump meter is only as good as the driver that knows how to use it, How hard is it to look inside and see exactly what the slump is, c'mon guys. If you look then you know exactly what it is and shouldn't ever have a wet or dry load, right. (old school I know), but it works. PS I have a slump meter and never use it, to many problems. Pea gravel, lightweight, 1" slump, 7" slump 1-5 yds, it simply is not calibrated for these mixes and sizes.

[concretejoe]

I had a dispatcher once who had all the slump meters painted over with black paint.

[mauserman]

Jul 15, 2008 20:38:54 GMT -5 Mixer Driver 69 said:

Rookie here.

I've learned that slump meter + eyeball + my ear (as in how the mix sounds in my drum when in full charge or wound up) = slump.

Damned good answer for a rookie .

I "ear tune" my mud and train my trainees to do the same.....against the strict orders of my employer.

I also teach my trainees to gallon count instead of relying solely on the gauge.

[wileycoyote]

I do the gauge-sound-sight method. The gauge will read differently when you start getting into the nice gooey high strength stuff. As long as you figure out what the gauge on YOUR truck does, you'll be ok, they're all different.

[booger]

What I tell our new hands... " Flip your ladder down and climb your butt up there and look at it" That's the best way to learn. They don't listen to me either. That's why they are always coming back to get 'dried up'.

[BillyCement]

Oct 25, 2009 18:32:33 GMT -5 booger said:

What I tell our new hands... " Flip your ladder down and climb your butt up there and look at it" That's the best way to learn. They don't listen to me either. That's why they are always coming back to get 'dried up'.

You're right, Booger. After awhile you'll know by the sound of the mix what it looks like. But, in the beginning you have to actually look at it.

[Jason]

This is from the point of view of a front discharge driver. 4 yards or more: 2" 1800, 3" 1500, 4" 1300, 5" 1100, 6" 900. 4 yards or less: 4" 800 slumps up are down from there are per line ie. 3" 900.

If I want to look at my load the mudd has to be rolled up. So the sound thing does come into play and generally mudd is only rolled up when I think the load might be border line wet. 5" plus is borderline wet where I am at so as a rule I dont leave the plant at anyting more than 4" unless it is stated on the ticket and even then its a risk.

We have been doing alot of mason grout lately, then I wet up to about 500 on the meter and tell the contractor I'm a 10" when really, I am 12" plus but they are happy. Then the trick is to keep it in the barrel going down the road, but that's another story.

[savagesam]

Mort consider yourself blessed that you learned with out one. Better to be able to tell by sight. Where I work if you leave the yard with a wet load, and the cont. rejects it, you just cost your self a days pay. I second the trainer that makes them climb up and look. My trainees look at every load until they are no longer in training.

[simple2man]

Every truck is different. It measures the hydyalic pressure it takes to turn the drum. So differnt size engines,drums,build up,fin size,ect will effect it. Best thing is to do it the old fashion way by looking then compare it to your slump meter. After a while you will get used to it and can just use the meter. I have been using one for seven years and it is more accurate than than looking. I still will ask a inspecter what slump he got and compare it. YOU MUST BE ON LEVEL GROUND!!! If your nose is pointed down the load will be wetter than the gauge. If pointed up will be tighter.(on a front , probably opposite in a rear). My truck works for 3 yards of more. others may be different. hope it helps.

[yag]

Slump indicators DO NOT "measure" slump. They measure hydraulic resistance. There is only one method for determing slump and it is found in the ASTM guidelines. In fact, the only applicable use of the word slump is if it's used in relation to the accepted slump test procedure.

ASTM C-143
Standard Test Method for Slump of Hydraulic-Cement Concrete
9.2 Bias
"This test method has no bias since slump is defined only in terms of this test method"

Everything is else is just opinion and B.S.

Even the accepted test procedure has tolerances (precision) like plus or minus 1 or 1.5 inchers for a 4 inch slump so the test really doesn't prove anything either

Read ASTM C-143

[uscfb15]

I only use the gauge as a very rough estimate. Most of the time I look at the concrete to get a better idea of what slump it is likely to be. Honestly though, the best and only way to truly tell the slump is to do a test.

We do a lot of crazy mix designs. 14000 psi white concrete with more chemical than water. The concrete is more like glue than anything. It looks like its a 5, but do a test and find its a 10" slump.

When we first started doing these kinds of high strength mixes we tested them in the yard. They filled a loader bucket and a guy was able to walk across the concrete without really sinking into it. Did the tests and concrete was a 10.5" slump. Gauge on truck read 1500psi @ 1400 rpm.

After getting to know your truck, and getting to know the mix designs themselves, you learn how to better "gauge" what the load is without testing it. It comes down to experience really.

[sherry]

Hey guys. Just started driving a mixer. Got the driving part mastered lol. I drive plow in the winter. But the slump thing has got me a little stumped. Is there a chart out there that will help me get my loads at least close to whats on my bill. My dad drove mixer for almost 30 years and used to take me to work occassionally so ive got a clue but he's gone now so i Cant ask him.

[sherry]

I was taught by dad to climb up. Take a look. Listen to how it sounds and then check the slump meter to see what it reads but not to trust it.

[readymix5544]

hey guys I am new in the industry and have just bought a truck and start driving it next week. my trainer was not all to helpful on teaching me

how to read the Hydraulic pressure meter gauge on the trucks. I was wondering if someone can help me make up a card or give me some kind of indication on slumps.
we do our orders in mm


he has advised me that he reads his 100mm slump at 2000psi is this correct?

where do you ready 80mm and 90mm on the psi gauge? can someone give me abit of a run down so I can make up a little card to put in my truck.


would be most thankfull