Composite modeling to predict shrinkage of concretes containing supplementary cementitious materials from paste volumes

► Developed two-step composite models to predict shrinkage from pastes containing SCMs. ► Compared the accuracy of the results from lab-scale results. ► Validated the models with external practical sources of shrinkage data. ► Compared the proposed models with different existing code-type models. The inclusion of supplementary cementitious materials (SCMs) such as slag, fly ash and silica fume into ordinary concrete diverts SCMs from landfills, reduces CO2 emissions, and produces durable and sustainable concrete. Concrete shrinkage is a significant parameter for durability. There is no systematic research on predicting the shrinkage of concrete mixed with various SCMs starting from paste properties. In this study, a two-step composite model is developed to predict concrete shrinkage from the paste level to the specimen level for 14 concrete mixtures containing only-slag, only-fly ash, only-silica fume, and slag plus silica fume, fly ash plus silica fume, and slag plus fly ash at two different water-to-cementitious materials ratios (w/cm). The composite model is used to find the shrinkage of mortar from paste properties in the first step, and then the range of the concrete shrinkages is determined using the shrinkage of the mortar and the Hashin–Shtrikman bounds [16] with the corresponding elastic modulus. The accuracy of the proposed models is evaluated using shrinkage data obtained through lab-scale experiment. The prediction models are found to agree well with the experimental data. Also, data from external sources are used to compare with the proposed models. Finally, these proposed models are compared with existing shrinkage models such as: ACI 209, CEB MC 90, and GL 2000. It is observed that the proposed model agrees more closely with the experimental results from the present study than the existing shrinkage prediction models.