Concrete Products

MAR 2013

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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INNOVATIONS REPORT CALORIMETRY DEVICE PEGS NEGATIVE BINDER AND ADMIXTURE COMBINATIONS Isothermal calorimetry measures the heat a cementitious binder generates in a cement paste or concrete specimen as an indicator for the rate of reaction, which is key to engineering properties such as workability, set time and early strength development. Calorimetry is widely used to study the effect of different chemical admixtures and binder compositions on the rate of reaction, and in concrete, detect unwanted interaction between complex admixture molecules and binders. The I-Cal 2000 High Precision Calorimeter HPC is a two-channel isothermal model for testing cement paste, mortar or concrete. Cement and concrete professionals typically deploy the unit to: I-Cal software plots a thermal hydration curve as the ambient temperature around the sample is kept constant. The temperature is set via software interface with a feedback loop to ensure optimal control, while precision sensors measure the heat flow generated by the cementitious binders reacting in concrete during the first day. I-Cal 2000 HPC also features Calmetrix's proprietary system of variable reference cells to adjust the thermal reference mass for each sample, thereby allowing for increased flexibility and better precision. I-Cal-generated data is retrieved and analyzed with Calmetrix's advanced CalCommander software, encompassing a suite of analytical tools to make heat of hydration studies easy as a "oneclick" experience. Total energy by unit of mass is automatically calculated and a report is generated in the standard required format. I-Cal 2000 HPC is also fully compliant with ASTM C1702—Standard Test Method for Measurement of Heat of Hydration of Hydraulic Cementitious Materials Using Isothermal Conduction Calorimetry. The unit's design results in lesser sensitivity to outside conditions, equating to more consistent results and a robust performance in non-air conditioned rooms. I-Cal 2000 HPC is a high-precision calorimeter with a large sample size, which makes it suitable for all applications in cement and concrete applications. Like Calmetrix's other isothermal calorimeters, the I-Cal 2000's main uses are found in research and development, plus investigative work on concrete properties, along with daily quality control needs in cement and concrete production. — Calmetrix Inc., Arlington, Mass., 617/203-2090; www.calmetrix.com • Determine heat of hydration of cement (e.g. ASTM C1702) or cementitious materials; • Predict or estimate paste or mix setting times and hardened specimens' compressive strength; • Determine activation energy for maturity, strength and thermal crack prediction; • Test sensitivity of temperature variations; • Test resolve sulfate imbalance issues; • Optimize mix design, select admixture type and dosage, or supplementary cementitious material volume; • Troubleshoot complex mixes and detect potential binding material–admixture incompatibility; and, • Test sensitivity of small variations in admixture or other material content. WWW.CONCRETEPRODUCTS.COM MARCH 2013 | 37

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