Difference in consumption of admixture - reg

[VIDHYA SAGAR]

Dear Sir,

I enclosed the summary of difference in admixture consumption.

Please guide what will be the reason.

We have done calibration just one month ago only.

While i am doing trial mix, bleeding occurred when increasing the dosage of admixture more than 0.45%.

But now 0.57% is going without any bleeding or segregation.

Thanks.
Vidhyasagar.

 

[Dnyan Deshmukh]

what kind of RMC plant you have.

Type of admixture dosing is direct by motor on basis of setting liter/sec.
Or do its weight batching cylinder.
In case of cylinder or weight batching of admixture, do it have a stop valve just above weight batching cylinder to stop the flow.


Also i would like to know the meaning of reg (you write reg almost in all your threads)

Do answer above question, so that the correct possible reason can be found and you can control it at your plant.

Higher dosage of admixture my give you nightmares in terms of delayed setting, low strength at 3 and 7 days.

Its a good subject of discussion - this kind of problem happens almost in all plants but many engineers wont even look at it due to lack of knowledge (its a very big subject, will write more on it later).

simple solution adopted by many which damages the concrete is, reduce admixture dosage and add water. if the admixture batcher is inconsistent, then it will give you real trouble as you not even able to figure out when you killed admixture and sent water to kill the concrete till you do the compressive strength test of concrete.

A good Quality control is something like, what you are doing now. Taking corrective actions on points which either gone wrong or may go wrong.

 

[VIDHYA SAGAR]

1. What kind of RMC plant you have?
CP 18.

2. Type of admixture dosing is direct by motor on basis of setting liter/sec.
YES.

3. Also i would like to know the meaning of reg (you write reg almost in all your threads)
Reg - REGARDING.

4. Presently I tried to reduce to input the value of admixture from 0.45 % to 0.40% and increased water for required work ability.
But some times segregation and non-cohesive noticed.
Because while submitting re-conciliation report, it will be a problem for me.

5. Now I escalated the issue to the management.
Requested to do calibration again by expert.
When I have done calibration with the help of 1 kg and 500 g weigh stones, it shows almost correct reading at display.

6. Any good idea requested.

Regards,
Vidhyasagar.

 

[Dnyan Deshmukh]

4. Presently I tried to reduce to input the value of admixture from 0.45 % to 0.40% and increased water for required work ability.
But some times segregation and non-cohesive noticed.
Because while submitting re-conciliation report, it will be a problem for me.



Regards,
Vidhyasagar.

When the discharge of admixture is measured in liter per sec you need to do following thing.

Ensure, only single type of admixture is used for all concrete as the density, viscosity and specific gravity are not same for all type of admixture.

The calibration of dispencing motor should be done by pumping Admixture through it as per set value and verifying it by collecting the discharge on other end.

To do the above you should know the specific gravity / density of admixture.

Water have specific gravity of 1 or density of 1000 kg/cum so it can b easily reconcile as the ration of weight to volume is same

i.e. - 1 liter discharge leads to 1kg of discharge

in case of admixtures, the specific gravity/ density plays important role in measurements.

example : admixture have specific gravity of 1.2 or density of 1200kg/cum

So when i say its 1 cum it is actually 1200kg and not 1000Kg

same way 1 liter corresponds to 1.2 Kg

So in order to calibrate and pour the correct quantity of admixture in concrete.

You need to convert admixture weight to liters (as the motor only measures / dispense flow in liter per sec) and then you should first calibrate it.

Example - I set 1 liter and dispense it in auto mode, collected the flowed quantity of admixture and measured its weight + volume.

same way repeated up to max quantity of admixture dispensed in a batch of concrete + 1 Liter.

After doing the calibration and finding the consistent results you can dose admixture without any worry.

Hope the above details will help you in identifying the issue.

 

[VIDHYA SAGAR]

Thank you sir.
I will do typical calibration method as guided.