IQM Meter System™
Expandable Maturity Meter System
For Concrete Strength Determination

• Purchasing Notes
• Applications
• Features & Benefits
• Product Information
• Specifications

IQM-Meter™

The James IQM System enables fresh concrete to be easily and completely monitored in the field for improved safety, quality assurance and optimum setting time.

Purchasing Notes

• The M-IQM-4010 Single Channel Maturity Meter, M-IQM-4040 Rs-232 Interface Cable & Software and M-IQT 4011 work together as a system, please review the information below.

• Consumables: M-IQM-4011 (1 meter (3 foot) K Thermocouple)

Applications

• Premature Form Stripping in cold weather can be avoided.

• Excessive summer heat exposure is controlled.

• Loading, prestressing or post tensioning as well as lifting and/or form removal can be performed safely

• Optimum scheduling of form removal, prestressing, post tensioning, and highway loading.

• Artificial heating and cooling of concrete is minimized

• Rework due to concrete not fully cured is reduced.

Features & Benefits

• Modular design facilitates optimum number of monitoring locations.

• A visual indicator shows field personnel that the required maturity is reached at each location.

• Construction personnel with minimal training can easily implement monitoring function.

• Multiple use thermocouple sensor lowers costs.

• Documented quality control of each pour.

• Faster and safer form stripping.

• ASTM C-1074 & ASTM C-918

Product Information

Designed specifically for monitoring and analyzing fresh concrete, the IQM™ Module is programmed with the required Equivalent Age of the concrete under test. Once this preset maturity number is reached, a visual indicator will flash continuously, providing an effective, automatic indication that the concrete has reached the desired level of maturity.

Software and interface cable allow direct uploading of the data to a Windows PC environment where it can be imported into any spreadsheet, word processor or graphing program for further analysis. Temperature history can be graphically displayed with respect to time.

The IQM™ software will create maturity indices from the complex Arrhenius equation according to ASTM procedure. The strength gain can be calculated and all these parameters can be graphically displayed with respect to time. The James IQM System™ enables fresh concrete to be easily and completely monitored in the field for improved safety, quality and optimum stripping time. Its modular design facilitates number and choice of monitoring locations.

The system generally consists of multiple units of M-IQM-4011 units on the structure logging the temperature and programmed with the proper activation energies. These monitor the critical and most temperature sensitive area's of the structure. Each unit is connected to a single thermocouple (M-IQT-4011). The units are then programmed with the M-IQM-4040 software and a P.C.. Once the concrete has reached the proper cure point the temperature time history can be retrieved with the software (M-IQM-4040). This makes the IQM System™ flexible to accomodate a single location or multiple locations on a structure.

Typical Application

A multi level concrete building is under design and its construction is to be controlled with the IQM-Meter™ to meet performance specifications.

Laboratory tests indicate that the concrete specified is of satisfactory quality. The maturity vs. strength relationship obtained during laboratory tests is shown in the figure below.

The structural engineer has specified that the slab forms can be removed when the concrete has reached a minimum strength 3500 PSI. To allow for unanticipated variations in the concrete properties, the contractor has decided that he will remove the forms when the concrete strength is at least 5% greater than the required 3500 PSI, i.e., when strength is 3675 PSI. The figure below shows that this strength level will be reached when the maturity is 59 Hrs.

The IQM-Meter™ thermocouples, therefore should be inserted in the freshly placed concrete at critical locations. The modules should be programmed with an equivalent age of 59 hours. Once the light on the last meter starts flashing, maturity value has reached 59 hours and the forms can be removed.

The IQM System

The temperature history is recorded by the IQM-4010 K Thermocouple Module, which can store over eight thousand temperature readings. Intervals between readings are specified by the user and can vary from one minute to twenty-four hours. Designed with the latest in microcomputer technology, the module is rugged enough for the harshest construction environments.

The module is programmed with the required Equivalent Age of the concrete under test. The red light on the module will flash continuously once this number has been reached. This provides a simple and effective automatic indication that the concrete has reached the desired level of maturity at that location.

Generally, sensors are inserted at critical points subject to the most extreme temperatures. Using the modular IQM-Meter™ System, there is no limit to the number of sensors that can be embedded in the wet concrete. The sensor giving the lowest maturity number indicates the area with the lowest strength, and this sensor will be the last to signal that the desired maturity has been reached.

The economical M-IQM-4040 PC Software and cable interface allow direct uploading of the data to a Windows environment P.C. The data, then, can be easily imported into any spreadsheet, word processor, or graphing software package for further analysis. Temperature history can also be graphically displayed with respect to time. The IQM™ software will create maturity indices from the more complex Arrhenius equation according to ASTM procedure. Strength gain can also be calculated via accepted methods. All of these parameters can be graphically displayed with respect to time.

Theory

The maturity method is a technique for predicting strength based on the temperature history of the concrete. The extent of the cement hydration depends on how long the concrete has cured and at what temperature. Maturity is a measure of how far the hydration has progressed.

The equation developed by Arrhenius allows for greater variation in cement types. It assumes a non-linear relationship for the determination of a maturity index and is suitable for a wide range of temperatures. The mathematics of the Arrhenius equation is more complex but it gives more accurate strength predictions over a variety of cement types. The maturity index is expressed as equivalent age in hours referred to a specific temperature, and is a function of time, temperature and the activation energy of the cement.

Specifications