How To Measure The Strength of Traditional Concrete
We all know that concrete is strong, but how strong is it? It depends on how you measure. Many different factors affect a concrete’s strength.
How Strong Is Traditional Concrete?
We all know that concrete is strong, but how strong is it? It depends on how you measure. It’s also important to recognize that many different factors affect how durable a particular concrete mix is.
· The Ratio of Water to Cement- The lower the ratio, the stronger the cement (and the harder it is to work with)
· The Proportion- Water, cement, air, and an aggregate mix of sand and gravel, need to be proportioned just right. For example, too much cement makes a smooth mix that’s easy to pour, but it also easily cracks.
· Mix Time- Up to a point, the longer you mix, the stronger the mix, but once you have mixed beyond that point, the concrete becomes harder to work with—and weaker.
· Curing- The longer the cement can be kept moist, the stronger it will be. Therefore, it’s essential to be careful when curing in cold or hot temperatures.
The most accepted measurement of concrete strength is called compressive strength. This will assess the performance of a given concrete mixture and its ability to withstand loads. To evaluate the compressive strength of a mix, cylindrical specimens of the concrete are broken in a machine that measures this type of strength in accordance with ASTM standard 39.
Pounds Per Square Inch
Compressive strength is measured in pounds per square inch (psi). A higher psi means a stronger, more durable mixture. Unfortunately, it also means the mixture will likely cost more. The minimum acceptable range of psi for your project will depend on what your structure needs to withstand and for what it will be used.
Some examples are:
· Footings and slabs on grade 3,500-4,000 psi
· Suspended slabs, girders, and beams 3,500-5,000 psi
· Traditional walls and columns 3,000-5,000 psi
· Pavement 4,000-5,000 psi
Higher psi is required in colder climates and those with freeze/thaw cycles.
Tensile strength measures the ability to resist cracking or breaking under tension or flex. Cracks occur when tensile forces are greater than the tensile strength of the material. Because traditional concrete has much lower tensile strength than compressive strength, it must be reinforced with materials such as steel.
Flexural Strength is one indirect measure of tensile strength, or how much the concrete can resist flexing or bending. Usually, this is 10-15% of the compressive strength. This is measured when the concrete is still wet.
How to Strengthen the Concrete You Have
Once your concrete is poured, you can still strengthen and improve its durability. Have it coated with a long-lasting, beautiful concrete coating! Our Experienced team at Concrete Coatings of Minnesota can even overlay your garage floor in the winter. Contact us today.