A systematic review on the evaluation methods for the flexural toughness of cement-based materials: From classification analysis to case study

The enhancement of toughness of quasi-brittle cement-based materials holds significant importance in modern concrete science. Flexural toughness serves as a key indicator for assessing the toughness of cement-based materials has garnered widespread attention. However, due to the different emphases of the indicators in various evaluation methods for flexural toughness, significant challenges with consistency persist in existing evaluation results. A systematic review of flexural toughness evaluation methods is thus necessary. The presented review primarily summarizes the test methods and evaluation methods for the flexural toughness of cement-based materials. Specifically, the section on test methods elucidates the fundamental principles of flexural toughness testing and describes typical test schemes and setup parameters. For the evaluation methods, these are categorized as energy, energy-ratio, strength, strength-ratio, and improved methods. After the comparison and analysis of these methods, a novel toughness evaluation method is proposed. Eventually, a case study is conducted to compare the differences between typical evaluation approaches. The significance of this review is underscored in offering valuable insights towards the formulation of rational toughness indexes and the establishment of unified standards for flexural toughness assessment in cement-based materials.