From the initiation of hydration when water is added to cement until the end of service life of cement-based materials, the influence of water permeates almost the entire lifecycle, comprehensively affecting both the development and degradation of their properties.Water transport is a critical fundamental factor determining the durability of cement-based materials (CBMs) and service life of structures. Since most concrete structures under service are unsaturated, capillary water absorption is the primary and efficient mechanism for water transport in concrete. An in-depth analysis of capillary water absorption process and sorptivity is of great significance for quantitatively studying and improving the durability of CBMs.This study systematically investigates the capillary water absorption process and its anomalies in CBMs. While existing theories attribute sorptivity anomalies to factors such as gravitational effects, material heterogeneity, and secondary hydration of unhydrated cement particles, certain experimental phenomena remain inadequately explained. Through macro- and micro-scale testing combined with theoretical modeling, it is hypothesized that the unique physicochemical interactions between water and C-S-H gel may underpin these critical anomalies.Although sorptivity testing is operationally simple, its results are highly sensitive to experimental conditions (e.g., temperature, humidity, and initial saturation). The moisture state of specimens plays a decisive role in sorptivity measurements, while inconsistencies in testing protocols can lead to disparate outcomes. Consequently, adopting a scientifically rigorous and practical testing methodology is imperative. This paper reviews international standards for sorptivity testing, including the widely recognized and scientifically reliable ASTM C1585—20 and ISO 15148:2002. However, these standards exhibit limitations, such as short testing durations that overlook the significance of secondary sorptivity. Given the anomalous long-term absorption behavior of CBMs, a systematic consideration of the two-stage sorptivity process is essential. Furthermore, China urgently requires the development of a national testing standard tailored to its specific material and environmental conditions.To elucidate the influencing factors of sorptivity, this study compiles and analyzes experimental data from diverse studies. The results reveal that cement content, water-to-cement ratio, and the dosage of supplementary cementitious materials profoundly alter hydration kinetics, hydration products, and pore structure, thereby significantly affecting sorptivity. Beyond material composition, variations in pretreatment methods (e.g., drying protocols) also induce substantial discrepancies in test results due to differing moisture states. Moreover, the coupling effects of these factors further complicate the interpretation of sorptivity behavior. Therefore, during the sorptivity test, it is crucial to adopt a scientific pretreatment protocol to minimize the impact of drying, equilibration, and moisture content on the test results.The study also explores correlations between sorptivity and other macroscopic performance indicators. Sorptivity demonstrates strong linkages with transport properties such as permeability and electrical flux, as these metrics are fundamentally governed by pore structure. Additionally, sorptivity exhibits predictive potential for mechanical properties and durability outcomes, including carbonation resistance, freeze-thaw durability, and sulfate attack resistance. Compared to other durability indicators, sorptivity not only boasts a relatively straightforward testing process, but its primary advantage lies in its high sensitivity to durability changes in long-age concrete. It also provides highly accurate assessments of the carbonation resistance of cement-based materials. Furthermore, it contributes effectively to evaluating frost resistance and sulfate erosion resistance. When used in conjunction with other durability indicators, sorptivity enables a comprehensive assessment of the durability performance of cement-based materials. As a durability indicator, sorptivity shows promise in forecasting the service life of cement-based materials.In conclusion, this work underscores the need for refined theoretical models, standardized testing protocols, and comprehensive investigations into the coupling mechanisms governing sorptivity. Addressing these challenges will enhance the reliability of sorptivity as a critical parameter for optimizing material design and durability assessment in cement-based systems.Summary and prospectsCement-based materials exhibit water sensitivity due to their unique physicochemical interactions with water. Current understanding and quantitative characterization of capillary water absorption (sorptivity) require further refinement through integrated theoretical and practical studies. Notably, the two-stage sorptivity mechanism, particularly the physical significance and engineering implications of the secondary sorptivity, demands deeper exploration to enhance its practical application.Critical anomalies observed in sorptivity evolution highlight the urgent need to develop more scientifically robust testing protocols. A standardized framework for evaluating concrete quality based on sorptivity should subsequently be established.The measured sorptivity is significantly influenced by material composition and mix design parameters, including cement type, supplementary cementitious materials, water-to-binder ratio, curing conditions (temperature and humidity), aging, and drying pretreatment. Systematic investigations into the correlations between sorptivity and material composition are essential to optimize mix designs for improved durability.Although sorptivity demonstrates varying degrees of correlation with mechanical properties, other transport indices (e.g., chloride diffusion), and accelerated durability test results, it exhibits unique potential as a complementary indicator for assessing concrete durability. Integrating sorptivity with conventional metrics could enhance the accuracy of service life prediction models for concrete structures. However, further theoretical, experimental, and field studies are imperative to validate its application in engineering practice.In summary, advancing research—spanning mechanistic interpretation, standardized testing, material optimization, and durability assessment—will provide critical insights into the performance and longevity of cement-based materials in real-world environments.