DYNA JOURNAL ENGINEERING

Key words:

hormigón, metodología experimental, caracterización de materiales, incendio, transformaciones físico-químicas. concrete, experimental methodology, materials characterization, fire, physic-chemical transformation.

Article type:

ARTICULO DE INVESTIGACION / RESEARCH ARTICLE

Section:

RESEARCH ARTICLES

ABSTRACT
Conventional thermogravimetric analysis requires small sample volumes to perform the experiments and, in the case of concrete, it is very difficult to take into account the effects of aggregates and moisture migration during tests. In the present work, an experimental methodology inspired in thermogravimetric methods was developed. The methodology proposed permits to assess the behaviour of small concrete samples exposed to a fast unidirectional heating, taking into account the effects of aggregates and moisture. For validation purposes, three types of normal strength concretes under two different heat exposures have been analyzed. Cylindrical concrete samples of 150 x 300 mm were cast. After curing cylindrical cores of 95 millimetres in diameter were extracted and shaped to 48 ± 2 mm in height. The samples were exposed to a two different heat fluxes (35kW/m2 and 75kW/m2) for 30 or 60 minutes. Mass loss rate and temperatures were measured every 1 second. Additionally, the heat transfer process was also monitored using infrared thermography. Experimental results shows that the methodology proposed is suitable to evaluate different hydro-thermal processes that take place in concrete exposed to fi re as the free water release, decomposition of calcium silicate hydrated and the decomposition of Porlandite. Initial moisture content of concrete plays a direct influence en mass loss rate at high exposure condition. No significant differences were observed at the lower heat flux. At the same exposure conditions, samples with lower moisture content shows lower mass loss rate.
KEYWORDS: concrete, experimental
methodology, materials characterization, fire, physic-chemical transformation.