Measuring Concrete: PSI and Slump

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Every concrete project requires a distinct mix that possesses an appropriate strength and consistency. Both PSI and slump play an important role in measuring concrete.

PSI is easily defined as how many pounds per square inch a surface can resist. For standard concrete jobs, this compression strength typically ranges from 3,000-4,000 PSI. While a 3,000 PSI concrete is ideal for concrete walls,  concrete sidewalks fall within the 4,000 PSI ballpark. High-rise buildings or foundations in water require a PSI of 6,000 or more.

The slump test is used to measure concrete consistency. Concrete is poured into a cone and rodded according to proper procedure. The cone is then removed, allowing the concrete to “slump.” The slump is the number of inches that the concrete moves from its original position when the cone is removed.

A slump of 1-2 inches is typically difficult to work with because of its low water content. A 4-5 inch slump is ideal to pour and maneuver to maintain concrete durability, while a slump that is 6 or more inches should only be achieved with the use of concrete admixtures that won’t sacrifice the durability.

Quality Control at Ozinga is responsible for testing these factors, along with measurements of the temperature and air content of concrete. This helps them to ensure that each load of concrete is appropriate for a specific job. Learn more about our Quality Control professionals in the video below. 

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