81 / 2022-04-15 16:02:02

Establishment of a prediction model of the failure thickness of concrete under sulfate attack

Concrete, Durability indicators, Prediction model, Sulfate attack

The durability of concrete under the sulfate attack environment is hard to predict as the deterioration performance is not described quantitatively. The indicators, such as strength, elastic modulus, mass, and length variations, are used widely to describe the effect of sulfate attack on concrete structures. However, these indicators do not provide sufficient information to assess the damage mechanisms. Moreover, they are difficult to obtain accurately in the actual engineering environment.

In the present work, sulfate attack experiments were carried out and the compressive strength, dynamic elastic modulus, and the concentration of sulfate ions with depth were measured. The durability failure index of concrete materials under sulfate attack was defined according to the mechanism of sulfate attack on concrete. The failure thickness was obtained by linear interpolation according to the calculated critical concentration of sulfate ions. Then the correlation analysis of the failure thickness and the change rate of the dynamic elastic modulus and compressive strength of concrete was carried out. The results indicate that the failure thickness can reflect the changing trend of the mechanical properties of concrete under sulfate attack. Then a prediction model for the failure thickness which is the square root of the attack time, was established. Furthermore, using the previously established chemical-diffusion-mechanical sulfate model, the influences of sulfate solution concentration, initial aluminate content of concrete, and diffusion coefficient on failure thickness were sensitivity analyzed. The results show that the failure thickness increases with the increase of the sulfate solution concentration and the diffusion coefficient, and the changing trend of the influence on the failure thickness presents a logarithmic curve. Whereas, the increase of aluminate concentration decreased the failure thickness to a certain extent, showing a negative linear correlation. The established model was verified by an experimental test, the results indicated that the prediction thickness was close to the test results and the error was acceptable.

In this research, a new durability failure index, failure thickness of concrete materials under sulfate attack was defined. And it’s validated that it can reflect the changing trend of concrete macro-mechanical properties under sulfate attack. Furthermore, a prediction model for the failure thickness was established in relation to sulfate solution concentration, concrete initial aluminate content, and diffusion coefficient. These studies help to further develop the durability design and life prediction of concrete structures under sulfate attack environments.