How Much Liquid Fortifier To Use In Hypertufa & Concrete Recipes

Admixes? Liquid Fortifiers? Acrylic Strengtheners?
What Is Their Purpose and How Much To Add
To Your Hypertufa and Concrete Recipes

I get emails quite often asking me about “liquid fortifiers” and exactly what are they, what do they “do”, and how much should be put into a ‘tufa or concrete recipe. So, today I’ll share what I do know about using various types of admixes.

First, as is commonly referred to either here on my blog, or in forums that discuss hypertufa and concrete garden art recipes and projects, the term “admix” (or “admixture”) and “fortifier” and “liquid bonding agent” are usually synonymous. Basically, an admix is an acrylic liquid and is used as strengtheners to enhance the longevity of the cured object.

Though not always necessary to use in a recipe, in many circumstances folks add in some admix as “insurance” that their object will be “stronger”, but most times because they are making items that will go through a lot of freeze/thaws due to the climate they live in; or because the object will be a stepping stone or rock that might take more abuse than a planter or trough would. Also, many people working with pure concrete recipes (versus a ‘tufa project) want very thin-walled objects, such as when they’re making hollow garden spheres. An acrylic admix added into the recipe allows thinner walls that will hold up and not crack apart.

Some acceptable and widely used acrylic bonding agent admixes used are:

  • Latex paint – yes! Ordinary latex paint – interior or exterior
  • Probond Concrete Bonder made by the Elmer’s Glue company
  • Quikrete’s Concrete Bonding Adhesive
  • Elmer’s glue – yes! White El;mer’s glue

Next, there is a misconception that admixes will make your cured object completely water proof – nope. Though there is a bit of water-proofing that happens because of the nature of the admix ingredients, an admixture’s sole purpose is to make the object much more durable and strong.

The next concern many crafters have is: Do I use just admix, or do I add some into the water and if so, how much water and how much admix do I use?

First, let me state that for the basic backyard crafter, there really isn’t such a thing as an “ideal ratio” you’ve got to use for maximum strength. If you are a professional using concrete in a commercial-type application … then yes, ratios of all your ingredients will be critical.

But, many of us have found that even a small amount like 10% admix added into the water makes a noticeable difference in the strength of the object, and also often in the speed of the curing time. This being said, folks may use the acrylic admix fortifier up to a ratio of 25% – but now it may start to get pricey, unless you are using leftover latex paint that would ultimately be thrown out. And I’ve read of those who use admixes at 100% and swear by the result. I cannot recommend 100% admix as I’ve no experience doing so.

admix reduces your water need,as prev. stated,so pieces are less impacted by that old freeze/thaw cycle.I use about 25%(depends on the conditions of the day,doesn’t it?)admix in my masks(coulda done without,but want my clients to get bang for buck)and 100% in anything that has to hold water.
Now,I’m branching out to make thinner,harder concrete pieces for your wall(about 3/8-1/2 inch down to an edge)so I’m trying other additives like Silica fume and superplasticizer to see what I can make concrete do.As they used to say,so very long ago,”Verrrrrrry interesting!”

Paul, I’ve been using acrylic polymers for quite a while in my work, laying stone floors etc, and I find they are excellent at bonding, and imparting strength and also a little flexibility to concrete/adhesives, however they don’t make the product entirely ‘water-proof’. You need an admix that is designed specifically for that, and add it into the mix water before adding the water to the sand/cement. These products are expensive, but you may be able to purchase them in small quantities at your local hardware store.
The polymer acrylics will make the product a lot more waterproof than it would have been without it, though.


  1. Richie L. says:

    Thank you for posting this! I’ve got a tufa project I want to try but have been holding off since I knew I ought to put something extra into the recipe to make it stronger, but wasn’t sure what.

  2. Claudia says:

    You’re very welcome! Good luck and I wish you success with your project.

  3. What can I add to hypertufa mix to make it act more like clay?

  4. Claudia Brownlie says:

    Hi Susan: You would be defeating the entire purpose of using a hypertufa recipe if you want a clay-like material.

  5. Christine says:

    Is there any difference between an acrylic concrete fortifier and a concrete plasticizer? I’ve made a few hypertufa planters in the past without any additives, they’ve all been outside exposed to the elements & are all over 10 years old. Other than some chipping around the top edge they have all held up, but I’m wanting to start making bigger pieces, and some tufa mushrooms, so I feel I ought to add something to improve strength. Any words of wisdom & advice from someone with more experience would be appreciated.

  6. Christine says:

    As an FYI, if this makes any difference to the answer to my above posted question, I live in central Illinois, USDA zone 5. The projects I’d like to make will sit out all year. My winters are highly variable anymore as far as freezing temps, snowfall etc.

  7. Claudia Brownlie says:

    Hi Christine: First, congratulations on your success with making long-lasting hypertufa planters. I think you’ve figured out by now that the minimal chipping around edges is something that can’t really be avoided for objects left outside for many years in freeze/thaw conditions.

    In trying to explain the difference (which there is) between an an acrylic concrete fortifier vs. a concrete plasticizer, how about the following to explain:

    Concrete acrylic fortifier is an acrylic resin admixture designed to enhance bonding and water resistance of concrete patching materials, stucco, surface bonding cement, thin-set mortars and tile grouts.

    Concrete plasticizer will reduce water consumption, helps to increase the consistency of the wet concrete, has leveling capabilities, increases the initial and final strength and density of concrete, will reduce shrinkage, and also the increases the permeability of concrete and cement-based materials.

    So, since you said, “…I feel I ought to add something to improve strength” I will wager you should try working with a plasticizer, as that product supposedly helps to increase the final strength.

    I would, as I always suggest to folks, to first make a small hypertufa object using the plasticizer to get the hang of working with it in the recipe mixture, plus so you will be assured that all is well throughout the entire process. And also so that you know your object cures properly, etc. And also, keep good notes on the ratios of every ingredient you use. I think you already know that will come in handy for future projects.

    I hope this information has helped you. Good luck with your bigger hypertufa projects! 🙂

  8. Claudia Brownlie says:

    Sounds like you’ve already mastered making ‘tufa objects that can withstand your environment – you said you’ve got items that have been left outside for over 10 years, so … this being said, I really don’t think there is anything else i can add to my other reply that will shed more insight.


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