How Superplasticizers Work in Concrete Countertop Mixes
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- Опубліковано 2 лис 2022
- This video demonstrates how superplasticizers work in concrete countertop mixes, then explains the science behind it.
For a complete video showing the entire mixing process, see • Superplasticizer for c...
See concretecountertopinstitute.c... for more information and for Alpha Pro Fluidizer. - Навчання та стиль
excellent explanation
As a medical doctor, I know very little about material science but I have a moderate understanding of chemistry. I found this video amazing, informative, and brilliant. Great product! Wish there was a medical application for it. 😂
Well Done Sir. Thank You.
Hey I'm looking for an answer on mixing in s.p. there nothing new we have been using them for the whole 17 years I've been driving mix for so I'm very familiar with the product what I don't get is where I'm from B.C. Canada they tell us to mix it for 1 min per meter so 10 minutes on a 10meter load. To me this is way to long and does not make sense to me. I can not find anything on actual mixing times for adding S.P. you got anything? Or info on this.
The time frame is probably to ensure that the superplasticizer is fully dispersed into the truck. 10 minutes of mixing for 24000 kg of concrete doesn't seem very long to me, especially when inadequate mixing could have a profoundly negative impact on the quality and consistency of the concrete.
@@TheConcreteCountertopInstitute so what I should have said is we add the S.P. on site after fully mixed from plant.
@@markrobert6014 Ah, I see. Then it's even more important to mix thoroughly. I don't know about the superp your plant uses, but our superp is more effective when adding early, before the cement. You are by neccessity adding it late in the mixing process.
@The Concrete Countertop Institute we add when batched as well every load. We will add extra on site for high slump like 200 millimeters slump/ 8 inch slump. They want to mix for 10 mins on site that extra added s.p.
We are currently using visco 1000 for about 6 months now previously last 10 years roughly was glenium 3030. Before that was rehobuild.
@@markrobert6014 I'm not familiar with those particular products, but I would definitely follow what the batch plant recommends. I'm sure it's important for proper dispersion.
What effect do these superplasticizers have on compressive strength and ductility?
Superplasticizers don't directly make concrete stronger or more ductile. What they do is allow for the use of lower water to cement ratios which *are* directly responsible for higher strengths and improved properties. Excess mix water, which is often used to increase workability, is responsible for a host of concrete problems and deficiencies, most notably lower strengths, excessive shrinkage, higher porosity, low durability and many other problems. Therefore, lowering water to cement ratio is the best and easiest way to improve concrete.
Superplasticizers also increase the dispersion of microfine particles including cement and pozzolans, which in turn helps improve material uniformity and physical properties. Finally, superplasticizers can help make the concrete more fluid and easier to consolidate, helping to eliminate voids, and this also improves material properties.
@@TheConcreteCountertopInstituteSo what’s the main causes of segregation and bleeding in concrete with admixtures like superplasticizers and how to control it?
@@ashrafkarim1826 Superplasticizers reduce the viscosity of the cement paste, changing it from a thick paste to a runny liquid. The higher the viscosity, the more stable the cement paste is, meaning it's able to support and suspend larger, heavier particles in it. As the viscosity decreases, it is less able to maintain a degree of uniformity in the mixture. When segregation occurs, the cement paste is too thin and watery and the solids settle out. As the coarse and fine aggregate settle out due to gravity, they self compact, and the void spaces between the particles decreases. This forces the watery cement paste out, where it collects at the top of the casting. Segregation is controlled several ways, but the simplest way is to make sure you do not overdose your superplasticizer. This is where trial batches become important, as it's the most practical way to determine what the threshold dose is for your particular mix and superplasticizer. Another way is to alter the base mix design to incorporate more ultra fine particles. Switching which superplasticizer you're using also works. Different superplasticizers have different strengths, so switching to a less potent one may solve the issue, and some superplasticizers incorporate viscosity modifying additives (VMA), further helping to stabilize your mix and reduce the likelihood of segregation occurring. And VMA's can be used on their own to reverse segregation during mixing, as they increase the viscosity of the cement paste to a level where the particles no longer settle out. VMA's can be sophisticated admixtures, affecting the static viscosity more than the dynamic viscosity.
@@TheConcreteCountertopInstituteThanks
Here, we always have an issue with our concrete segregating and bleeding when we use superplasticizers. We use about 1% of the cement we use. Is it more advisable to reduce the percentage of admixture use or changing the design mix? We don’t wanna employ viscosity improvements chemicals.
The design mix here is with 20mm and 20mm gravel, sand and cement
@@ashrafkarim1826 I suspect that the dose that you are using is too high. Did you run trial batches to determine the optimal superplasticizer dose? 1% is quite high for many superplasticizers. It's always easiest to use less of an admixture than it is to reformulate your mix design. Always take the path of least resistance and change one variable at a time.