Is early drying shrinkage still determined by the mesopore content? A case study of cement paste with minerals

Abstract

Long-term drying shrinkage is deemed to be relevant with the mesopore content of cement paste, so is early drying shrinkage still determined by the number of mesopores? This was not the case. Through combining the measurement of water loss and pore size distribution (PSD), this study provides an explanation of early-age drying shrinkage of cement paste with different types/contents of minerals (i.e., blended cement paste) added, and a corresponding prediction model was proposed in terms of its early shrinkage. The results show that during hydration, instead of the mesopore content, the water loss due to evaporation in capillary pores of cement paste was well correlated with its early drying shrinkage, which could be attributed to a small portion of mesopores rather than all mesopores have lost water at an early age. Meanwhile, a parameter rs, which was defined as the radius of the pores where the meniscus formed, was calculated by combining the results of PSD and water evaporation, and its reduction led to an increment of drying shrinkage of specimens. Finally, the outcomes obtained from the proposed prediction model fitted well with experimental data, revealing the effectiveness and accuracy of the model in foreseeing early drying shrinkage of blended cement paste.