Study Of Full-field Drying Shrinkage Inside Cement-based Materials

Cement-based materials are the largest and widest material used in the world currently.In cement-based materials family,foam concrete widely attracted researchers'attention because of its excellent properties.As to concrete,the durability of foam concrete is a hot spot of study all the time.In the study of durability,problem of drying shrinkage which is one of volume deformation caused deterioration inside concrete is complicated.As an important factor which deteriorate the performance of foam concrete,there is no effective means to control it.So it is necessary to study the whole process of the full-field deformation inside foam concrete.In this study,the preparation,maintenance and drying shrinkage of foam concrete specimen were all in standard room.3D image data before and after deformation in drying age were obtained through x-ray CT scanner and 3D reconstruction software.We calculated the full field displacement and strain inside specimen with digital volume correlation(DVC)method which has a high precision.With the maps of strain before and after deformation during drying age,we observed and analyzed the drying gradient and the shrinkage heterogeneity.Furthermore,we established a process of whole drying shrinkage inside foam concrete.Besides the study of drying shrinkage,we also used a dual CT grayscale method based on ex-DVC to analysis the change of moisture inside foam concrete.In this research,the relationship between local drying shrinkage and local moisture migration was also analyzed.A relationship of lever between moisture migration and drying shrinkage was established.