Effects of intermediate drying periods on the scaling behavior of concrete under freeze-thaw deicing salt attack
Final Report Abstract
The effect of intermittent drying periods on the damage development of cement-based construction materials under freeze-thaw and de-icing salt exposure was investigated. It was found that drying events occurring between freeze-thaw cycles significantly impact the magnitude and rate of surface scaling. Depending on the type of cement and the prevailing temperature, humidity, and CO2 concentration during drying, the tested mortars and concretes generally exhibit increased surface scaling behavior immediately after drying, but a reduced surface scaling behavior in the subsequent stages of the freeze-thaw and de-icing salt test. Using 1H NMR measurements, the drying process was comprehensively characterized and correlated with the surface scaling behavior. This revealed that changes in surface porosity and moisture content are primarily responsible for the surface scaling behavior. This finding was used to predict surface scaling in neural network based model using only 1H NMR measurements. Additionally, a novel measurement method using 3D laser scanning was developed, enabling precise determination of surface scaling even in materials that are highly susceptible to surface scaling. The results of the experimental program were used to calibrate a 3D-coupled hygrothermo-mechanical (HTM) model for simulating internal stress and strain states during freezethaw processes. Using the HTM model, it was possible to identify a strong dependence of the fluid pressure and the associated deformations during a freeze-thaw load on the permeability of the material.
Publications
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Frost‐Tausalz‐Widerstand von Mörtel: Einfluss der Expositionsbedingungen im jungen Alter. Beton- und Stahlbetonbau, 117(12), 985-997.
Haynack, Alexander; Timothy, Jithender; Kränkel, Thomas & Gehlen, Christoph
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What Is the Internal Pressure That Initiates Damage in Cementitious Materials during Freezing and Thawing? A Micromechanical Analysis. Applied Mechanics, 3(4), 1288-1298.
Timothy, Jithender J.; Haynack, Alexander; Kränkel, Thomas & Gehlen, Christoph
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Analyse des Frost‐Tausalz‐Widerstands zementgebundener Baustoffe mittels 3D‐Laserscanning. ce/papers, 6(6), 1189-1196.
Haynack, Alexander; Timothy, Jithender J.; Kränkel, Thomas; Gehlen, Christoph & Thiel, Charlotte
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Can a Hand-Held 3D Scanner Capture Temperature-Induced Strain of Mortar Samples? Comparison between Experimental Measurements and Numerical Simulations. Mathematics, 11(17), 3672.
Haynack, Alexander; Zadran, Sekandar; Timothy, Jithender J.; Gambarelli, Serena; Kränkel, Thomas; Thiel, Charlotte; Ožbolt, Joško & Gehlen, Christoph
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Characterization of Cementitious Materials Exposed to Freezing and Thawing in Combination with Deicing Salts Using 3D Scans. Advanced Engineering Materials, 25(19).
Haynack, Alexander; Timothy, Jithender J.; Kränkel, Thomas & Gehlen, Christoph
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Effect of Chloride Concentration on the Freeze-Thaw Resistance of Concrete. RILEM Bookseries, 911-921. Springer Nature Switzerland.
Haynack, Alexander; Schneider, Alexander; Timothy, Jithender J.; Kränkel, Thomas; Gehlen, Christoph & Thiel, Charlotte
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Numerical Analysis of the Freezing Behavior of Saturated Cementitious Materials with Different Amounts of Chloride. Materials, 16(19), 6594.
Zadran, Sekandar; Ožbolt, Joško & Gambarelli, Serena
