Ultracal30

robin kolloschinski

Hello there,

anyone can explain me how Ultracal30 works? i am working in contruction and its common knownledge here that you shouldnt mix gypsum with cement, so i am a little bit confused.

thanks in advance
robin

Chris Ellerby

Adding gypsum to a cement mixture that already has a calculated percentage of gypsum may cause a chemical imbalance resulting in setting issues.

In construction there are many applications that contain gypsum like http://en.wikipedia.org/wiki/Gypsum_concrete which is around 24% gypsum.  Portland cement which contains 2-10% gypsum is also common.  In Portland cement the gypsum is added to retard the hardening process and control setting time.

Also, in the effects industry the term "cement" is often used when referencing materials like Gypsum plaster, dental stone, other hardening stone mixtures.

For mold making and tooling the properties of a gypsum plaster like Ultracal 30 are ideal.

• surface hardness
  
• high compressive strength
  
• low expansion
  

I would imagine those same properties would be a hindrance in some construction applications. 

Here are a couple data sheets with a bit more info:

• http://www.fxsupply.com/msds/ultracal_30.pdf
• https://www.freemansupply.com/tables/usg.htm
  
• http://www.freemansupply.com/datasheets/USG.pdf

Out of my own curiosity, what are some of the reasons you've heard for not adding gypsum?  (I'm always curious to learn about material application in different industries)

Hope that helps!

/Chris