A strength-based mix design method of fly ash concrete with superabsorbent polymer based on Powers' model

Using fly ash (FA) and superabsorbent polymer (SAP) in construction promotes sustainability by reducing cement consumption and enhancing concrete durability. However, the mix design of FA concrete with SAP has to be improved due to the uncertainty of entrained water content and early strength (0–28 days). To fulfill this objective, a numerical study was conducted to assess the influence of FA on the computation of entrained water content, utilizing a model derived from Powers' model. Experimental and numerical assessments were then conducted to explore the effects of SAP on the mechanical properties, total shrinkage, and pore structure of concrete. Results revealed the modifications are crucial to accurately calculate the minimum entrained water content required for full hydration of the binder material in concrete. Moreover, the influence of SAP on cubic compressive strength (0–28 days) can be described by differences in porosity, and the conventional correlations were still applicable to describe the correlation between cubic compressive strength and other mechanical properties. Notably, pore refinements and shrinkage reduction of concrete were observed owing to the use of SAP. These findings would promote theoretical research, mix design, and practical applications of FA concrete with SAP.