Análise da influência de baixas temperaturas na resistência à tração do concreto

Abstract

Due to the mechanical resistance, its characteristic highlight, the concrete is the most used material currently in construction. However, to develop this property the material needs to be cured in a favorable situation so that the hydration reactions of the cement, responsible for developing such a characteristic, take place. It is known that such reactions are exothermic, so lower temperatures go against this guideline, and may influence the resistance gain. There are situations where the exposure of concrete to lower temperatures is inevitable, so the present work sought to understand how the concrete develops its resistance to traction until the age of 28 days exposed to a temperature of 5 ° C. Evaluating the results obtained by the research in question, it was possible to prove the negative influence of the low temperature on the tensile strength gain. At 3 days of age, cured concrete at low temperature can only acquire 85.42% of the resistance acquired by a concrete cured at room temperature. At 7 days, the resistances approach, but the cure at low temperature still shows as a negative factor, where the concrete cured at room temperature is approximately 10% more resistant. At 28 days, the resistance of the two curing models evaluated in the present study has similar statistical behavior, but does not assume the same values, and the average tensile strength of the specimens cured at low temperature did not reach 94% of the resistance obtained by concretes cured at room temperature. Therefore, it can be concluded that the recommendations of the standards that warn of the precautions to be taken for the exposure of fresh concrete to low temperatures are really necessary as this prevents structures from being damaged due to the non-attainment of the tensile strength predicted for a certain age.