Experimental evaluation and modeling of drying shrinkage behavior of metakaolin and calcined kaolin blended concretes

In the first stage of the study presented herein, the findings of an experimental study on drying shrinkage behavior of concretes incorporated with high reactivity commercial metakaolin (MK) and calcined kaolins (CKs) were reported. Free shrinkage strain measurements as well as corresponding weight loss were measured over 60 days of drying. Four different types of kaolins obtained from local sources were calcined and used as mineral admixture for concrete production. Moreover, commercial metakaolin of high purity was also used as reference material for comparison. In the second stage of the study, prediction models through gene expression programming (GEP) and multiple linear regression (MLR) were derived. The data set used for training and testing covers the experimental data presented in this study as well as additional ones collected from the literature. The parameters considered for developing the prediction model are related to the characteristic properties of mineral admixture, concrete composition, and drying period. As a result, CK incorporated concretes revealed comparable performance with MK incorporated ones in terms of drying shrinkage and weight loss. Furthermore, the prediction models yielded strong correlation with the experimental results. Statistical analyses also revealed that the proposed models can be handful tools in predicting the drying shrinkage strain of the concretes modified with MK.