Can You Mix Plaster of Paris with Cement?


Both plaster of Paris and cement have countless uses. Cement is one of the key ingredients used in concrete, while Parisian plaster is a quick-setting material often used to make casts. While these products each have many uses, can they be mixed together? Keep reading as we take a look! 

It is possible to mix together plaster of Paris and cement, especially for casting and troweling purposes. Neither of these materials contains an aggregate, which can impact the structural integrity of the final product; however, it is possible to also add these. Mixing these materials for sculpting purposes is not advised due to the formation of ettringite.  

In this article, we’ll look at Paris plaster and cement and the many uses of these products. Once we’ve done this, we’ll look at what happens when these materials are combined. If you’re contemplating mixing plaster of Paris with cement, you should read this article first! 

What are the Differences Between Plaster of Paris and Cement? 

Before we look at whether or not you can mix plaster of Paris and cement, let’s take a look at exactly what these products are. This will give you a better understanding of the uses of these products in your home improvement or renovation project. 

Cement, of course, is one of the main ingredients used to create concrete. Essentially, cement functions as a binder in concrete, allowing it to be used in construction. Cement is a chemically manufactured material that is made up of eight different compounds, with Lime accounting for 60-65% of the compound. 

There are countless ways that cement is used in the construction of residential and commercial buildings. Not only is this a material that can be used during the construction of your home, but it can be used afterward in various decorative ways. 

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From decorating your patios, pool decks, driveways, staircases, and more, there are many great ways cement can be used for home improvement. If this idea of decorating your home with cement intrigues you, then you’re sure to love plaster of Paris. 

When it comes down to plaster, there are three different types. Firstly, there’s lime plaster, which is made from sand and hydroxide. The second type is cement plaster, which is made from a combination of Portland cement, plaster, sand, and water. The third type, of course, is plaster of Paris. 

For those not familiar with plaster of Paris, it’s a powdery white substance made from hydrated calcium sulfate. Also known as Parisian plaster, this lightweight material is widely used to make casts, which is attributed to plaster of Paris’ unique quick-setting abilities and the fact that it does not shrink. 

In your home, there are many possible ways to use plaster of Paris. Not only is the material fire-resistant, but it can be used to make decorative sculptures and castings for both residential and commercial properties. 

As you can see, there are clearly many different ways that both cement and Paris plaster can be used in your home improvement projects. However, is it possible to use these materials at the same time? If you’re wondering whether or not you can mix plaster of Paris with cement, keep reading! 

Can You Mix Plaster of Paris with Cement? 

If you’ve found yourself questioning whether plaster of Paris and cement can be mixed together, you’ll be glad to find out they can be mixed! However, this depends on how you want to use these materials. Keep reading as we explore how these materials can be used together – and whether or not there are better alternatives! 

While Parisian plaster and cement can be mixed together, there are a few important factors that could impact the structural performance of this mixture. For this reason, it’s important to be aware of these considerations when combining these materials. 

When you combine cement with plaster, there is something neither of these materials has: aggregates. In construction, aggregates are raw materials of a granular nature. This includes materials such as sand, gravel, crushed rocks, binders, and fibers. 

As we mentioned earlier, cement is one of the main ingredients used to make concrete. Another major component that makes up the total volume of concrete is the use of aggregates. The inclusion of these materials strengthens the concrete mixture and provides thermal and elastic properties. 

Given that there are no aggregates present in a clean mixture of Paris plaster and cement, you can see how your project could be impacted in terms of its dimensional stability if the appropriate measures aren’t taken. At the end of the day, this ultimately depends on how you want to use this mixture. 

There are a few aggregates that are commonly used in both concrete and plaster, including polyester, nylon, glass, and metal fibers. Using one of these in conjunction with your Paris plaster and cement concoction can increase the structural integrity of the mixture once it sets. 

For the best results, these materials should be combined in their dry, powdered state to be thoroughly mixed. For even better results, you’ll want to consider adding an aggregate to balance the mixture and provide much-needed missing properties. However, are there alternatives to mixing cement with Parisian plaster? 

Are There Better Alternatives to Mixing Cement with Plaster of Paris? 

As we established above, it is possible to combine plaster of Paris with cement. For casting and troweling purposes, this can be great. However, there is one drawback when it comes to using a combination of these materials for decorative sculpting. For this reason, there may be better alternatives to using, depending on your desired application.

When plaster of Paris and cement combine, it can often result in the formation of ettringite, which can influence decorative sculptures made with this mixture. Ettringite, which is hydrated calcium aluminum sulfate hydroxide, is a result of the reaction between the aluminate phases in cement and sulfate ions. 

By adding plaster of Paris to cement, you are essentially adding additional sulfates to the mixture. This encourages the formation of ettringite, which can result in an expansive reaction of the final product once the material has been set. However, in certain applications, such as filling potholes, this is actually the desired outcome! 

As we said, it ultimately depends on your desired use of the mixture. However, if you wanted to use a mixture of Parisian plaster and cement for sculpting purposes, you may want to consider using an alternative. 

Earlier in this article, we mentioned the different types of plaster that are available. One of them, of course, is Parisian plaster, which we have already covered. However, cement plaster, another type we briefly mentioned, could be the perfect solution for those looking for a material to use for decorative coating purposes. 

Using plaster cement will not result in the formation of ettringite. Alternatively, if you already have plaster of Paris on hand, you can simply add sand to it as an aggregate. This will provide a similar effect to mixing Paris plaster and cement and will reduce the overall time it takes for the finished product to harden. 

Conclusion

In this article, we broke down everything you need to know about plaster of Paris, cement, and the combination of these two materials. From the suitable uses of this mixture, such as casting or troweling, to why alternatives may be better for decorative sculpting, we covered it all! At the end of the day, whether or not you combine Paris plaster and cement depends on your desired application.

Best Home Fixer

I love fixing up my own home and I set up this blog to help others do the same.

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