An Analysis of the Destructive Influence of Water Saturation on the Durability of Concrete Exposed to a Fire
Journal Title: Safety & Fire Technology - Year 2016, Vol 41, Issue 41
Abstract
Aim: The purpose of this paper is to present the results of a study involving concrete, containing sanitary ceramic waste as an aggregate, in context of resistance properties to high temperatures. Standardized concrete specimens were subjected to initial saturation with water and subsequently exposed to a heating process according to a predefined “temperature-time” schedule. Based on the previous experiments, the authors obtained a concrete with increased resistance to the effect of fire and, simultaneously, resistant to effects of thermal spalling. Methods: Concrete specimens used for strength studies were developed using alumina cement mixed with sanitary ceramics waste aggregate. The first batch of specimens were saturated by complete submersion in water for a period of 5 minutes. Subsequently, the removed specimens were dried for 10 minutes. A second batch of specimens was fully submerged for 12 hours, and similarly to the first batch, the specimens were dried. Next, the prepared specimens were placed in a PK 1100/1 type medium range temperature furnace. The heating process was initiated at a predefined “temperature-time” schedule, until a temperature of 1000°C was achieved. Durability tests were performed 30 days after heating. Results: The derived test results verified the significant impact of moist conditions, in which concrete specimens were placed and secondly, the high temperature impact on the specimen durability. A porous concrete prepared based on the design experiences of refractory concrete after heating, which simulated fire conditions, was characterised by a compressive strength of 27 MPa. For the same concrete after submersion in water for 5 minutes and heating, the average strength value was 6.42 MPa. While for the concrete saturated for 12 hours the obtained compressive strength value was 5.79 MPa. Although specimens were subjected to the same manufacturing treatments and care, they absorbed different amounts of water. This was revealed by weighing and is attributable to their non-standard porous structure and significantly high absorption level of ceramic aggregate. The specimens were heated to 1000°C and no thermal spalling was observed for all tested specimens. Conclusions: Study results reveal the destructive impact that moisture can have on concrete, when exposed to the influence of fire. The cause of such a development is perceived to stem from the disturbance caused to the composite structure by the ingress of water, which increases in volume during the heating process. From a performed experiment it is evident that there is a need to conduct an evaluation of durability for all concrete elements, which are exposed to the influence of fire. Such elements, despite constancy associated with their external features, apparent invariable structure and form, in fact can have significantly lower durability parameters, which can only be revealed during laboratory tests.
Authors and Affiliations
dr inż. Bartosz Zegardło, st. kpt. dr inż. Paweł Ogrodnik
Keywords
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- EP ID EP90845
- DOI 10.12845/bitp.41.1.2016.3
- Views 139
- Downloads 0
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