In cold and drought environment, concrete shrinkage cracking caused by water loss is serious, and thus the freezing resistance of concrete is deteriorated. The waste ceramic particles were used as internal curing materials to prepare concrete, based on this background. Then, the influence of internal curing with ceramic particles on humidity field and temperature of concrete is analyzed by using temperature and humidity sensor. Based on the change mechanism of the internal humidity of concrete, the relationship between the curvature radius of liquid surface and the relative humidity is revealed. Taking water loss and water loss rate as the index, the water transfer law of concrete surface under ceramic particle internal curing was defined. Through the drying shrinkage test, the mechanism of improving the drying shrinkage of concrete by internal curing in ceramic particles was mastered. Finally, the effects of ceramic internal curing on cement hydration, interfacial transition zone (ITZ) and freezing resistance of concrete were studied. The results show that the relative humidity, water loss and water loss rate of concrete increase with the increase of ceramic particle content, and the dry shrinkage value decreases with the increase of ceramic particle content. Compared with ordinary concrete, when the ceramic particle content is 10%, 15%, 20%, 25% and 30%, and the test period is 10 days, the internal relative humidity of concrete increases by 0.52%, 0.67%, 1.55%, 2.55% and 3.05%, respectively. The drying shrinkage values decreased by 3.42%, 7.69%, 10.26%, 15.17% and 30.13%, respectively. When the test period was 1032 hours, the water loss increased by 1.08%, 5.15%, 7.90%, 12.69% and 14.49%, respectively. Furthermore, when the ceramic particle content is 20%, the initial normalized heat flow of concrete increases by 2.74 mW/g, and the normalized heat flow minimum increases by 0.324 mW/g. The minimum ITZ microhardness increased by 2.64 MPa, the ITZ width decreased by 5 μm, and the maximum crack width at the contact between ITZ and aggregate decreased by 0.89 μm. At the same time, when the ceramic particle content is less than 20%, the effect of internal curing on the freezing resistance of concrete increases with an increase in ceramic particle content.
Read full abstract