Maturity meter signals strength

Penn State engineers have developed a ‘smart’ maturity meter to estimate when newly poured concrete has reached the correct hardness and strength.

Penn State engineers have developed a ‘smart’ maturity meter to estimate and to signal by phone when newly poured concrete bridge supports, pavements, and road surfaces have reached the correct hardness and strength to be opened to traffic or the next phase of construction.

The meter prototype and accessory technology were developed by Dr. Paul Tikalsky, associate professor of civil and environmental engineering and David G. Tepke, a doctoral student, as part of Tepke’s master’s degree research.

The new maturity meter is said to be the result of integrating new digital phone technology with an existing concrete monitoring concept.

The concept, Tikalsky said, has been around since the 1940s but has only recently been employed in meters on the commercial market.

The Penn State prototype is said to be a ‘next generation’ meter that the developers estimate will cost less than those currently available. In addition, the Penn State meter provides real time evaluation and quality control information with cellular technology.

Ambient temperature, the heat generated by the chemical reactions in the curing process itself and the variability in the concrete mixture, as well as other factors, influence the rate at which concrete structures achieve their intended strength.

Currently, when concrete is poured to create a structure, small sample castings are made, for test purposes, to represent how the concrete is gaining strength in the actual structure.

The Penn State prototype uses the fact that the internal temperature of the concrete can be directly related to the time it takes to mature. Only a minimal number of castings need to be made for the Penn State method to be effective.

To determine the internal temperature, the prototype uses simple thermocouple technology, and then integrates it with a computer program-net-on-a-microchip, along with cell phone technology, to provide a ‘smart’ monitoring component.

In the Penn State prototype, sensor wires are snaked through the concrete forms before the cement is poured. After the cement is in place, the wires are connected to the maturity meter, which is, in turn, connected to a digital cell phone.

By calling up the phone, the developers can download the digital data and use software they have developed to convert the temperature data into a maturity rating.

Tikalsky notes that the system can be used to monitor the status of a structure remotely and sound an alert on a pager or phone when the concrete reaches readiness or an alarm if the concrete is in danger of freezing which can cause serious damage to the maturing structure.