Could Smart Concrete™ Replace Concrete Cylinders for Acceptance Testing?
In a typical construction project, the strength of the concrete is assumed to be the same as the strength of cylinders cast from that same load of concrete. Cylinders are made in the field, by a technician, and cured under standard conditions. The cylinders are not intended to measure the concrete in the structure, but rather as a check on whether the concrete producer batched the correct material. This test assumes a lot and fails often -- too often, for many reasons. So, is there a better method for acceptance testing of concrete in the field? Maybe a method that actually measures the concrete in the structure?
Smart Concrete is built on maturity. This is 65 year-old technology that contractors like and Engineers respect. Maturity is not new, and it is well proven (ASTM C 1074). Most important, maturity actually measures the concrete in the structure without influence of an unskilled technician or improper curing conditions. Maturity is best at measuring early strength of concrete up to maybe seven days.
So, when could maturity be used for acceptance? It makes the most sense when the strength of the concrete reaches design strength at an early age. This might be an applications with heavily over-designed mixes, where heating is used to accelerate strength, or when chemical accelerators are used to enhance setting time. In any situation where the design strength is achieved in the first few days is an ideal situation for using maturity for acceptance when coupled with the standard density test (ASTM C 138) as the check on whether the concrete producer batched the correct material.
Breaking concrete cylinders (ASTM C 39) has its place as a lab test to measure the potential strength of a concrete mixture, but has failed the industry too many times to be considered a reliable field test. The industry is ready for a change, and Smart Concrete built on ASTM C 1074 will be that change for concrete that reaches design strength at early ages.