451 Materials and Structures/Matériaux et Constructions, Vol. 30, October 1997, pp 451-464 0025-5432/97 © RILEM The present recommendation gives details of the appa- ratus and describes the procedure to determine the evolu- tion of the adiabatic temperature in a specific concrete. 2. DEFINITIONS A diabatic calor ime t er : a calorimeter is considered to be adiabatic if the temperature loss of the sample is not greater than 0.02 K/h. Semi-adiabatic calor ime t er : a calorimeter where the maximum heat losses are less than 100 J/(h·K). Coef f icient of t em per atur e loss a [K/h]: Decrease in temperature of the sample for unit time. T ime cons t ant τ [h]: Parameter of the exponential cooling curve. Coef f icient of heat loss α [J/(h·K)]: Quantity of heat lost from the sample for unit of time and for a unit tem- perature difference between sample and environment. T em per atur e incr ease of t he concr e t e sam ple θ s [K]: Temperature increase of the sample measured during hydration in a calorimeter. A diabatic t em per atur e incr ease θ ad [K]: True adia- batic temperature increase of concrete. T em per atur e incr ease θ HH [K]: Intrinsic temperature increase calculated from tests in a semi-adiabatic calorimeter. T em per atur e T s [°C]: Temperature of the sample. Foreword This Technical Recommendation was drafted by P. Morabito, Italy, and revised after discussion in Technical Committee 119- TCE and its subcommittee on hydration heat. 1. SCOPE One of the most important factors associated with thermal cracking in concrete is the evolution and distrib- ution of the temperature increase throughout the section at any time after casting. The temperature increase is a direct result of the heat evolved from the hydration of the cement. The majority of standard tests currently in use for mea- suring the heat of hydration of cement are carried out at a constant temperature. The prediction of the temperature increase of concrete from these results can be difficult, because these isothermal tests do not take account of the change in reactivity of the cement with changing tempera- ture and therefore do not reflect the conditions in the real structure where the temperature changes continually. The alternative approach is to use adiabatic or semi- adiabatic calorimeters in which are tested concrete speci- mens of the same mix as will be used on site. Such methods aim at determining the evolution of the adiabatic temperature increase under conditions which are very similar to those at the centre of a large pour. RILEM TC 119-TCE: AVOIDANCE OF THERMAL CRACKING IN CONCRETE AT EARLY AGES Recommendations RILEM TECHNICAL COMMITTEES TC Membership: Chairman: R. Springenschmid, Germany; Secretary: M. Plannerer, Germany; Editorial Secretary: J.-L. Bostvironnois, Germany; Members: P. Acker, France; S. Bernander, Sweden; R. Breitenbücher, Germany; K. van Breugel, Netherland; M.J. Coole, Great Britain; M. Emborg, Sweden; H. Grube, Germany; H. Hamfler, Germany; M.J. Hammons, USA; H. Huber, Austria; C. Jaegermann, Israel; F. Jung, Austria; M. Mangold, Germany; P. Morabito, Italy; P.K. Mukherjee, Canada; F.S. Rostásy, Germany; A.R. Solovjantchik, Russia; T. Tanabe, Japan; P.J. Wainwright, Great Britain. TCE1: Adiabatic and semi-adiabatic calorimetry to determine the temperature increase in concrete due to hydration heat of the cement The texts presented hereunder are drafts for general consideration. Comments should be sent to the TC Chairman, Professor R. Springenschmid, Institute for Construction Materials, Technical University of Munich, Baumbachstr. 7, D-81245 Munich, Germany, before 1 st February 1998.
TCE1: Adiabatic and semi-adiabatic calorimetry to determine the temperature increase in concrete due to hydration heat of the cement
Apr 28, 2023
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