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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Online Prediction of Strength Development in Precast Production Based on Cement Reaction Model
Author(s): E. Nordenswan and A. Kappi
Publication: Special Publication
Appears on pages(s): 133-140
Keywords: heating control; maturity; precast production; strength prediction.
Abstract:The throughput of precast concrete plants can be improved by controlled heating of the cast products. Presently many systems do measure maturity or degree-hours providing information about the strength development, but not sufficient data for accurate decisions for the control of heating. A heat control system has been developed based on an on-line predictive calculation of the temperature behavior of concrete and a maturity-strength model. The temperature is measured continuously and every minute a complete prediction calculation up to the target maturity and strength is made. If the target strength cannot be reached without heating by the target time limit, the system opens the valve for heating the mould, until the temperature is high enough. The predictive algorithm also provides an accurate estimation of the time when the prestress release or demoulding strength is going to be reached. The parameters for the cement heat generation model are obtained by semiadiabatic measurements of the production concrete. The system has been in use since 1999 and applied in over ten precast factories in Europe in hollow-core and railroad sleepers production. The system has reduced significantly the heating costs; reduced rejections caused by too early demoulding and improved production planning in the factories.
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