Insights into surface crack propagation of cement mortar with different cement fineness subjected to freezing/thawing

摘要

As cementitious material freezes and thaws, cracks may expand due to the weakness in the internal structure, the behavior that influences properties and potential applications. Hence, investigation of cement strength, which is affected by cement fineness, is prior to limit the propensity of cracking through the improvement of internal structure as well as the bond between cement paste and aggregate. In this regard, the tests of porosity, flexural, and compressive in macro-level and SEM/XRD/EDX analysis in micro-level were conducted to clarify the effect of cement fineness on variations of macro- and micro properties of cement mortar specimens subjected to different freezing/thawing cycles (50, 100, 150, and 200). The detection and tracking of cracks were also determined using image analysis. Based on experimental evidence, it was found that the influence of fine cement on the porosity and strength properties of cement mortar was greater than coarse cement; this also was clarified by changes of cement paste micro-structure. Moreover, the image analyses showed that the use of fine cement led to a decrease in the crack width, whereas the crack tortuosity to find the path growth was increased. Consequently, cracks behavior was found to correlate with the cement paste micro-structure, whose characteristics relate to the cement fineness. (C) 2019 Elsevier Ltd. All rights reserved.