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In cold climates, early-age cementitious material is easily threatened by frost damage, causing deterioration of material properties. To investigate the hazard and failure mechanism of cement paste due to early frost damage, the cement hydration process was divided into five stages via the electrical resistivity method, and then fresh cement pastes were frozen in five stages and two different temperatures, respectively. Furthermore, mechanical tests and X-ray computed tomography scanning were carried out to characterize the development of frost-related damage. The results indicated that the effect of initial frost time on strength growth is greater than that of freezing temperature, and the cement matrix can be considered completely damaged when frost-related damage occurs before the initial setting. The frost-related texture develops from outside to inside and the porosity of the sample frozen at the first three stages was higher than that of samples frozen at the last two stages. Finally, the frost-related damage could be divided into three types: flow extrusion damage, freezing expansion cracking damage, and flow extrusion-freezing expansion cracking combined damage. [ABSTRACT FROM AUTHOR]

This correction notice addresses an error in the article "Frost-Related Damage of Portland Cement Pastes at Early Age" by Zhuangzhuang Liu et al. The correction states that the Type B and Type C frost-related damages were mistakenly switched in the text. The authors apologize for the error and clarify that each instance of "Type B" should be "Type C," and vice versa. The correction has been made only in this erratum to preserve the published version of record. [Extracted from the article]

Calcium alginate capsule encapsulating rejuvenators are a new approach to enhance the self-healing property of asphalt, but the release and self-healing properties of calcium alginate capsules in asphalt concrete under cyclic loading conditions are still unclear. In this research, calcium alginate capsule encapsulating sunflower oil as a repair agent was synthesized and the oil release ratios of the capsules in asphalt concrete after compression loading were determined through a Fourier transform infrared test (FTIR). Then, strength and fracture recovery tests and DSR test were conducted to evaluate the effects of the released oil on the healing levels and rheological properties of asphalt concrete. Finally, computed tomography (CT) scan and SEM tests were conducted to study the morphology of the capsules to analyze the oil release mechanism of calcium alginate capsules. The test results showed that with the increase of the compression loading cycles, more oil was released from the capsules and the self-healing level of the asphalt concrete increased obviously. In addition, the oil released from the capsules softened the asphalt, decreasing the complex modulus and increasing the phase angle of the asphalt. CT scan images showed that after compression loading and healing, the capsules deformed slightly but maintained their spherical shape, indicating that the capsules could release the oil from the cavities due to shrinking and deformation upon compression loading and restore their original shape after compression loading. [ABSTRACT FROM AUTHOR]