The thermal decomposition of Ca(OH)2 polymorphs

Title: The thermal decomposition of Ca(OH)2 polymorphs
Author(s): James J. Beaudoin, Taijiro Sato, Peter J. Tumidajski
Paper category : conference
Book title: 2nd International RILEM Symposium on Advances in Concrete through Science and Engineering
Editor(s): J. Marchand, B. Bissonnette, R. Gagné, M. Jolin and F. Paradis
Print-ISBN: 2-35158-003-6
e-ISBN: 2351580028
Publisher: RILEM Publications SARL
Publication year: 2006
Pages: 3 - 13
Total Pages: 11
Nb references: 11
Language: English

Abstract: The thermal decomposition of different polymorphs of Ca(OH)2 with varying degrees of crystallinity and surface area was investigated. The nitrogen surface area values ranged from 3.7 to 31.1 m2/g. The presence of two separate and distinct thermal decomposition events was observed depending on the degree of crystallinity. Binary mixtures of Ca(OH)2 with substantially different degrees of crystallinity exhibited well defined thermal decomposition doublets. In addition Differential Scanning Calorimetry (DSC) experiments (for cycles of heating and cooling) performed in controlled environments pre-conditioned to various relative humidities (RH) also indicated the presence of two distinct endothermal doublets. The endothermic peak temperatures were dependent on the RH and temperature history of the Ca(OH)2 samples. An assessment of factors affecting the observed thermal behavior included: investigation of particle size and degree of crystallinity; observation of combined strain and particle size broadening (Williamson-Hall X-ray plots); heat capacity-temperature characteristics. A thermodynamic analysis of the thermal decomposition process is presented.

Online publication: 2006-08-02
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580028.001