What is self-consolidating concrete?
Self-consolidating concrete (SCC), or self-compacting concrete, is known for low yield stress, high deformability, and good particle separation resistance, as well as mid-range viscosity. Now, unless you are already a paving contractor or in the asphalt/paving industry, you are probably wondering what all that stuff means. Don’t worry, at Reliable Paving, concrete is our bread and butter, and we are happy to walk you through what it all means.
Low yield stress
Without getting into the specific mathematics of yield stress, yield stress level basically means the force required to permanently deform something. When many materials, namely metals, are submitted to force or pressure, they will bend. At a certain force level, the bending is “elastic.” This means that the material will revert to its original shape. The low yield stress of SCC tells us that it takes relatively little force to permanently change its shape.
High deformability, like low yield stress, sounds like a bad thing for concrete right? Deformability is the ability for something’s shape to be changed without breaking it. For example, iron is much more deformable than asphalt. And aluminum is much more deformable than iron. We will later get into how high deformability and low yield stress is a good thing.
Segregation (particle separation) resistance
Segregation resistance is how much an aggregate material — like asphalt or concrete — resists separating. Paving materials are made with binder and aggregate. Asphalt paving, for example uses a petroleum-based binder, which glues everything together, and various aggregate. The aggregate particles are made from small rocks and stones of various sizes. Basically, segregation resistance is the ability of the material to prevent the particles from coming apart in the mix. This can be during transport, placement, and as it sets.
If you’ve ever worked with oil, you know what viscosity means. It’s essentially the “thickness” of a fluid. The more viscous it is, the more resistance to flow. The moderate viscosity and segregation resistance of SCC means that it’s suspended particles are uniformly-distributed.
What are the uses of self-consolidating concrete?
Although it can be used much like normal concrete, SCC’s unique characteristics open it up to more advanced uses.
- Highly-complex formwork. The nature of this work make it a good candidate for SCC. It doesn’t require compaction, so it can simply be poured, and then it sets. Unlike normal concrete, it doesn’t develop honeycombs when setting in formwork. This makes it a great solution for architectural concrete as well, which often needs to have smooth surfaces.
- Locations where reinforcing rebar is not available. In some complex work, or crowded architecture, it may not be possible to use reinforced concrete. In comes SCC. It’s ability to resist particle separation helps keep it extremely strong throughout.
- Columns and beams. These structural concrete pieces often have to be shaped specifically, and can’t always accept reinforcing steel. Thus, SCC is a good solution, it is structurally robust and can be shaped variously. This is where its deformability and low yield strength come in handy.
- Pumped concrete and foundations. Because it compacts itself, SCC is great for solutions requiring concrete to be piped or pumped to a location. Unlike traditional concrete which must be laid and compacted, SCC can simply be pumped into an area, and will set itself. This means that no heavy compacting equipment is needed, as well as the space to perform compacting. The moderate viscosity helps it flow into compact and complex places and shapes, where it sets and becomes extremely strong.
What are the benefits of self-consolidating concrete?
Thanks to the section above, we can see where it is a useful addition to a construction. But what about the specific benefits to construction and paving contractors? How about benefits to the end users, who put this material in their buildings?
Savings on labor, time, and equipment
Because the concrete can simply be pumped into a location where it will set, it is faster and easier to install. Traditional concrete must be laid in segments, compacted with heavy equipment or screed. Screeding is the process of using a long tool (sort of like a car windshield wiper) on newly-poured concrete. The process removes excess concrete, flattens it, and ensures that the concrete is the right grade. Some concrete must be heavily compacted with heavy equipment. SCC is simply poured or pumped to a location, formed, and it does the rest. Vibrators are another tool used in setting concrete that ensure air bubbles come out and that the concrete is uniform. The vibrations from them though, can be deleterious to other newly-built structures at a job site.
- Less labor required.
- Less time required to place and set.
- Less equipment needed.
- Elimination of vibrations at the job site.
Easier to fill restricted areas
Viscosity level promotes it being pumped into small areas that traditional concrete is not feasible for.
Better properties when hard
Because it has deformability and low yield strength, it will change shape rather than break. This is good for finishing touches, and for repairs. It also makes it structurally more sound. SCC is simply a better structural material, with a smoother surface than traditional concrete. It’s improved uniformity helps it stay stronger and smoother.
You can read more about its benefits, construction, and its notable disadvantages in this article from NY Engineers.
Not sure which concrete is right for you?
If you aren’t sure what to use for your building project, leave it up to the experts. Reliable Paving has been in the industry for over 35 years. We know the best ways to do concrete and asphalt paving traditionally, as well as the newest trends and innovations. Come rely on our large, experienced, and professional team. Contact us today about what we can do to help you.