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Determination of hardened binder initial composition (CROSBI ID 196354)

Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija

Šustić, Igor ; Barešić, Jadranka ; Šipušić, Juraj Determination of hardened binder initial composition // Zement - Kalk - Gips international, 65 (2012), 10; 70-78

Podaci o odgovornosti

Šustić, Igor ; Barešić, Jadranka ; Šipušić, Juraj

engleski

Determination of hardened binder initial composition

In civil engineering practice, one frequently encounters questions about the causes of failure or malfunctions of construction parts i.e. of the materials of which they are composed. Those questions come not only from investors, but also from other parties involved in building construction and maintenance. The prime concern is the quality and quantity of the materials used for a particular malfunctioning construction part and the expense in time, human labor and materials needed to restore its full functionality. These questions are difficult to answer with certainty and there is a need for even better methods and procedures for the analysis of hardened inorganic binders. In the following, we outline some current practices of hardened binder analysis aimed at determining the initial composition of binders used for construction work. Cement-based materials hold by far the largest market share. However, the setting and hardening of cement-based materials is too complex for an initial testing of a hypothesis, i.e. if the carbon isotope ratio of CaCO3 can be used for the determination of the hardened cement mortar initial composition. As a result, in this work we are concerned with lime- based materials as a simplified model system. Examples of the use of the carbon (and oxygen) isotope ratio of the lime mortars can be found [1- 3], but mostly in the context of radiocarbon dating of ancient mortars. The difficulty of accurate, unbiased dating of old lime binders comes mainly from the presence of inclusions of unburned char in the original lime and the inherent difficulty of distinguishing between the calcium carbonate used as aggregate and that formed by lime setting. Lanas and Alvarez [4] and especially Lawrence et al. [5] used thermogravimetric analysis (TGA) for determination of the quantity of unreacted hydrated lime and calcium carbonate in lime mortar samples. TGA analysis of lime samples is widespread and relies on more or less well separated processes of mass loss of water from portlandite and CO2 from CaCO3. Standard methods for determination of the composition of binders taken from old/hardened structures are not very precise (ASTM C-1084-97) and the proposed research aims to contribute to the current methods of hardened binder composition determination. To the best of our knowledge, the method of carbon isotope 14C assisted determination of the initial composition of hardened binder is new and is therefore tested against the simplest inorganic binder i.e. lime mortar. The application of the same methodology for the analysis of hardened cement-based materials is in progress.

cement ; lime ; mortar ; isotope 14C ; thermal analysis ; hardened binder initial composition

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Podaci o izdanju

65 (10)

2012.

70-78

objavljeno

0949-0205

Povezanost rada

Geologija, Kemijsko inženjerstvo, Temeljne tehničke znanosti

Indeksiranost