Many people in the concrete industry still think that high strength cures all. This is, unfortunately, not true. High-performance concrete is certainly a tempting solution for increasing your concrete鈥檚 abrasion resistance. After all, its high compressive strength does make it tough and durable against abrasion. And it鈥檚 not even that hard to make. Increase the cement content. Keep the water-cement ratio low. Maybe add some silica fume. And the test results are pretty decent.
Sounds pretty good, right?
Well, don鈥檛 get too eager! High-performance concrete may have some benefits, but they come at a price.
To delve into that aspect, we first need to talk about the two main methods for creating high-performance concrete: adding silica fume and adding extra cement. Both are popular ways of strengthening concrete, but neither are efficient for increasing concrete abrasion resistance.
When Made with Silica Fume, This Concrete Offers Diminishing Returns
So, let鈥檚 say you want to go with the silica fume route. What are the likely results?
Silica Fume Does More to Increase Compressive Strength Than It Does to Increase Abrasion Resistance
According to done by the Amirkabir University of Technology in Iran and the Yamaguchi University in Japan, the results are not overly impressive when it comes to silica fume increasing abrasion resistance.
As expected, however, they did see good results for it increasing compressive strength. For instance, when adding 10% more silica fume to a concrete mix, the study鈥檚 researchers noted that the mix鈥檚 initial 35 MPa (5,000 psi) jumped to 50 MPa (7,000 psi).
To determine the impact that silica fume had on the abrasion resistance of this concrete, the researchers conducted a modified version of the . That allowed them to measure the mass loss of their 40-day concrete samples, showing an increase in compressive strength. And for every percent increase, there was a 0.33% increase in abrasion resistance. That eventually led to a maximum increase of about 13%.
This is certainly an improvement in a mix鈥檚 abrasion resistance. But it is a minor one.
It鈥檚 Just Not the Biggest Contributor for Your Concrete鈥檚 Protection Against Abrasion
In support of this view, done by a structural designer from Tacoma Engineers Inc. and a professor at George Brown College suggests a similar outcome. They noted that silica fume鈥檚 contribution to abrasion resistance did not have a significant impact. In fact, it was more important to consider the mix鈥檚 aggregate type and water-cement ratio.
They did also note that of course, with an increase in compressive strength, there was some increase in abrasion resistance.
So you can expect to see some benefits in abrasion resistance with a greater increase in compressive strength with silica fume. But it may not be worth it if you need better abrasion resistance.
Then, what about adding cement instead?
High-Performance Concrete with Extra Cement Is Better But Costly
Again, like with silica fume, you鈥檒l see a great increase in compressive strength when using extra cement. Scotland鈥檚 University of Dundee confirmed this with in 1991. During the study, researchers found they could increase cement content to raise a concrete mix鈥檚 27 MPa (4,000 psi) to 50 MPa (7,000 psi).
It also showed some promise of doubling the mix鈥檚 abrasion resistance. Still, for it to work, you鈥檇 need to increase the cement content by 80%.
That might not seem like much of an issue initially. But it won鈥檛 take long for you to see the problem when you look at the bill for your concrete. Adding so much cement has a literal high price attached to it, making it the least appealing way to boost your concrete鈥檚 resistance to abrasion.
Worse Still, It Can Come with a Number of Unwanted Side Effects
No matter whether you went with silica fume or extra cement, you are very likely going to see some downsides.
These Can Include Application Concerns
If you went with adding silica fume as it鈥檚 the more budget-friendly of the two options, you may end up facing application concerns. However, it depends on the amount you鈥檙e using. If you add less than 10% to your concrete mix, your concrete鈥檚 application will likely go on as usual. But , your concrete will become sticky, making it harder to place and finish.
Moreover, sometimes, the best overall result comes from using a concrete mix that is easy for the contractor to work with. In these cases, you might be better off avoiding silica fume.
Or They Might Include an Increase in Heat of Hydration, Which Can Lead to Other Structural Concerns
If you went with adding extra cement instead, you will have a more pressing concern to worry about: . After all, increasing your mix鈥檚 cement paste means increasing the mix鈥檚 hydration. And doing that generates more heat within the concrete due to the chemical reaction between the water and extra cement.
It can add stress to large concrete masses as they cool, leading to the concrete cracking. On top of that, more cement paste also creates . And that can . 聽That can in turn , joint filler failure, and more.
Another Concern Is the Additional Pollution That Comes from an Increase in Cement Content
The addition of more cement isn鈥檛 just a concern to structural integrity. It鈥檚 also a concern to the surrounding environment. Around two thirds of a ton of C02 is released for every ton of cement manufactured. So to add even more cement to your mix is only increasing your structure鈥檚 carbon footprint, which contributes to extreme weather events and .
You Don鈥檛 Have to Deal with These Issues
While it might seem like it currently, you don鈥檛 actually have to choose between either form of high-performance concrete. If you鈥檙e looking to significantly increase your concrete鈥檚 abrasion resistance and avoid the potential downsides of adding silica fume and extra cement, should be your go-to solution.
Hard-Cem Increases Abrasion Resistance without Application Concerns
As an integral hardening admixture, Hard-Cem is a unique solution for increasing abrasion resistance. It鈥檚 the only one of its kind on the market, and it鈥檚 capable of doubling your concrete鈥檚 abrasion and erosion resistance.
There鈥檚 no real concern when applying it either. You just add Hard-Cem to your concrete mix during batching, and that鈥檚 it! The admixture will go on to increase the abrasion resistance of your concrete鈥檚 paste and reduce abrasive wear and tear. It leaves no impact on your concrete鈥檚 workability or any other aspect, so the contractor can place and finish it like they are accustomed to.
It Can Even Make Your Project More Sustainable
What鈥檚 more, Hard-Cem can even decrease your structure鈥檚 carbon footprint! Because it raises the concrete鈥檚 surface wear resistance to counter abrasive and erosive forces, it mitigates the need to replace or repair your concrete over time. For instance, after seeing rapid abrasive damage in their mine鈥檚 original concrete, the owner of the in British Columbia, Canada, found that Hard-Cem helped them avoid at least two concrete replacement cycles. That let them reduce the concrete鈥檚 lifetime carbon footprint by 49.5%. And it was all thanks to making sure their concrete was durable enough.
For a Less Risky, More Green Approach, Hard-Cem Is Worth It
It鈥檚 not a conventional choice, but Hard-Cem has had more than 15 years to prove its worth. And it has done so many times for over 7 million m2 (80 million ft2) of concrete across North America. This has produced over the years, making Hard-Cem a proven and welcome addition to abrasion resistance solutions.
