Conception of an isothermal calorimeter for concrete - Determination of the apparent activation energy

Title: Conception of an isothermal calorimeter for concrete - Determination of the apparent activation energy
Author(s): M. Broda, E. Wirquin, B. Duthoit
Paper category : journal
Serial title: Materials and Structures
Abreviated Serial title: Mater. Struct.
ISSN: 1359-5997
Publisher: RILEM Publications SARL
Volume: 35
Issue: 251
Issue date: 2002-08-01
Publication year: 2002
Pages: 389 - 394
Total Pages: 6
Nb references: 10
Language: English

Abstract: The length changes of cement-based materials,mainly due to shrinkage and to thermal effects,often cause detrimental cracking.
In order to completely master the phenomenon,researchers must have a thorough knowledge of the involved mechanisms starting as soon as the setting of the material.
This will allow them to develop optimised compositions.
For that,the knowledge of the thermal coefficient of expansion is necessary.
On the one hand,when purely hydrical length changes are investigated,it allows to eliminate the thermal effects from the data.
On the other hand, when thermal effects must be accounted for,it allows an accurate forecasting of the behaviour of the concrete.
This paper focuses on the measurement of the thermal dilation coefficient and the follow-up of its evolution between the setting and the 24 th hour.
The proposed method is simple and the common devices to measure the 0-24-hour length changes are convenient.
Moreover,reliable measurements are obtainable as soon as setting,about 3 hours after pouring.
The results are within the range proposed in the literature.
They confirm that,while the material is ageing,its dilation coefficient a exhibits a continuously decelerated decay until it stabilises, between the 15 th and 24 th hour,at the value characterising the hardened material.
On a silica sand mortar,we measured (alpha) =18 µm/m/°C at the age of 3 hours and (alpha) =13 µm/m/°C for the hardened material.

Online publication: 2002-06-27
Classification: Scientific Reports
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/13793