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Everything You Need to Know About Concrete Setting
by TRP Ready Mix on December 8, 2020
From hardening to mixes and more
Concrete setting is a science that we don’t think about all too often. It’s usually “concrete gets hard; everything is good.” But on the contrary, construction businesses, renovation companies, and contractors know that there are so many factors that go into ensuring concrete is set properly for optimal functionality and longevity. Read this article to learn more so that you can make the right decisions before proceeding with your projects.
Read More: Concrete Pouring Done Right
What is concrete setting
Concrete setting is what happens when mixed cement changes from a fluid state to a solid state is called setting. The time required for it to set is called setting time. The setting time of cement and concrete are simultaneous.
How concrete setting impacts concrete hardening
Concrete setting and hardening are uniform in time. The way concrete sets is an important factor to determine how it will harden. Is the concrete going to set with many pores, or will the pores be minimal? This means, for example, that the hardened concrete may come out denser.
Read More: How To Cure Concrete Faster
Properties of hardening concrete
Durability
Once hardened, concrete is extremely resistant to any factors that emanate from the environment (frost, rain pollution, etc.). This is why concrete is well-suited for structures exposed to demanding and extreme conditions. Concrete is also extremely durable when mixed with quality. Read more about the importance of the mix below in the “Density and porosity” clause.
Mechanical strength
You want your concrete to be strong. Regular concrete strength varies between 25 and 40 MPa. If your concrete grades at above 50 MPa, it’s classified as High-Performance Concrete. This is because 50 MPa corresponds to a force of 50 tons acting on a square with sides of ten centimeters.
Density and porosity
Durability and mechanical strength come down to density and porosity. A denser concrete is less porous, and this equation makes the concrete better in its performance and greater in its durability.
To increase the density of concrete, optimize the dimensions and packing of the aggregate while reducing the water content.
Fire resistance
The advantages of hardened concrete include fire resistance, thanks to its ability to sustain itself against extreme temperatures once hardened. Concrete is non-combustible, and its thermal conductivity is low, making no additional fire protection to be required. The slow rate of heat transfer allows concrete to withstand extreme fire pressure without emitting toxic gases, smoke, or molten particles.
Thermal and acoustic insulation properties
Concrete structures are thought to enhance both thermal and acoustic insulation properties. Though many are surprised by this fact, concrete is a very good material for acoustic insulations but only blocks airborne noises. As a hardened material, it reduces acoustic performance in terms of impact noises. Many studios recommend the front wall being made of brick for this reason. In terms of insulation, concrete is an energy saver that can keep the outdoor elements from breaking through your heating. When living in a concrete structure, you may not need as much heat as you’d think to stay warm in the winter.
Impact resistance
Hardened concrete also offers impressive impact resistance, depending on the mix. You will want your mix to be minimally porous to improve density, making it highly durable and high performing as a structure or a road. Both structures and roads need to be highly impact-resistant in order to ensure the safety of people in the building and any traffic on the road.
How weather affects concrete setting
Cold weather slows down the setting process of concrete, and in some cases, it can stop it completely. This negatively impacts the concrete’s strength gain. Additionally, if the concrete sets while being exposed to freezing temperatures, the water in the concrete will freeze and cause it to crack. This significantly reduces its durability and the service life of the structure.
Read More: When is it Too Cold to Pour Concrete?
Read More: Curing and Pouring Concrete: Best Practices for Summer
Concrete setting isn’t ideal in high temperatures either. Hot weather leads to rapid water evaporation, and as a result, higher early strengths that create less durable structures over the long term. This may cause the concrete to experience a reduction in strength gain and potentially crack.
The best solution for this is to set concrete in weather ranging in the 10- to 20-degree Celsius range.
How mix design affects concrete setting
When using a licensed concrete supplier, make sure you choose wisely. The supplier you use determines the mix design, which will then determine the setting of your concrete. Concrete’s mix design is composed of cement, coarse aggregates, fine aggregates, admixtures, water, and air. Each of these elements plays a huge part in setting.
Read More: The Importance of Sealing & Finishing Concrete
- Larger coarse aggregates are more economical and reduce the amount of cement per unit of volume. This may also cause issues with the workability of the mix.
- Lowering the water/cement ratio will increase the strength of the concrete and provide better durability. This should be done with caution because it can also reduce the workability of the concrete.
- Using pozzolanic material, such as fly ash, to replace a portion of the cement is more ecological and economical. Though it slows down the setting process, it also provides enhanced properties to the concrete.
Concrete setting testing methods
It’s important to test concrete as it measures factors such as strength, consistency, unit weight, air content, and temperature. Running consistent tests on concrete can help you detect changes that may affect its long-term performance.
Here are different testing methods for concrete.
The Maturity Method is an accurate and non-destructive way to measure the effect of time and temperature on concrete. This method requires monitoring in-situ concrete temperature in a structure over time and calculating the effect that time-temperature history has on the maturity of the in-situ concrete.
The Pull-Out Test is the method to test fresh concrete. The tensile force required to pull a metal disk with a layer of concrete from the surface is related to the strength of the concrete. This test is normally used for early diagnosis of strength problems, which is a great way to determine your concrete mix for your construction.
If you are going to work with concrete for your upcoming project, it is important to understand the properties of each stage and how choosing the right type of mixture will affect the outcome of your construction. Make sure to work with a licensed professional to safely execute your contraction or construction needs.
