Polymer Concrete vs. Polymer Modified Concrete
What exactly is the difference between polymer concrete and polymer-modified concrete? The confusion is understandable. Both materials could have their place in acid-proof construction, but they are, in fact, two different things. Allow me to explain.
Polymer concrete uses a polymer binder in place of Portland cement. Polymer-modified concrete is Portland cement concrete with polymer solutions added to the mix to achieve certain properties. Like Portland cement concrete, the primary curing mechanism for polymer-modified concrete is hydration of the cement binder.
There are lots of different kinds of polymer concrete, and there are lots of different kinds of polymer-modified concrete. Some common types of polymer concrete are potassium silicate, vinyl ester, epoxy, and furan. When certain types of admixtures are blended into Portland cement concrete, the resulting mixes may be called polymer-modified concretes.
Resinous polymer concretes, such as epoxy, vinyl ester, and furan types, generally achieve compressive strengths multiple times that of polymer-modified concrete. They are also nonabsorbent and possess exceptional resistance to acid.
Potassium silicate polymer concretes are more like Portland cement concrete in that they achieve compressive strengths in the 3,500-4,500 psi range and have a certain degree of absorption. Unlike Portland cement concrete, potassium silicate concrete offers exceptional resistance to non-fluoride acids including nitric, hydrochloric, sulfuric, and phosphoric.
Polymer-modified concrete may have a lower degree of permeability or a higher density than unadulterated Portland cement concrete, but it is still essentially dependent upon Portland cement binder for its structural integrity. Portland cement, an alkaline material, reacts with acids, neutralizing the acid and while simultaneously destroying the concrete matrix.
Whether weak or strong, acid will attack Portland cement based concrete. Degradation of the concrete might take longer if it is very dense and, therefore, has less surface area. In an acidic environment, the relative improvement in chemical resistance of polymer-modified concrete over Portland cement concrete is usually not sufficient to ensure its structural integrity long-term.
Where corrosive chemicals are handled, Portland cement concrete is not a suitable material of construction on its own. In such environments, Portland cement concrete could be replaced with an appropriate polymer concrete or covered with a more chemical-resistant barrier. Examples of barrier linings include resin linings, acid brick and anchored thermoplastic.
This is not to say that polymer-modified concretes do not have a place in acid proof construction. Polymer modified concretes are typically less expensive than polymer concretes and are often used for concrete restoration work when construction time is limited. They can be used to quickly repair structural concrete and allow acid-proofing work to begin sooner.
It is important to understand the different capabilities of polymer-modified concrete and polymer concrete as they relate to acid proof construction. The terms are very similar and sometimes used interchangeably. Understanding that materials containing Portland cement binder are susceptible to acid degradation is a good first step in sorting out the differences.