Effects of multiple design factors on the mechanical properties and pore structure of ceramsite foam concrete

Compared to traditional aggregates such as crushed stone, ceramsite is lightweight and provides thermal insulation due to its internal microporous structure, which reduces density and inhibits heat transfer. To address the high susceptibility to cracking and significant shrinkage in conventional foam concrete, ceramsite can be incorporated to produce a lightweight, eco-friendly material known as Ceramsite Foam Concrete (CFC). This material not only effectively mitigates shrinkage and cracking but also, owing to its lightweight nature, thermal insulation properties, and ability to utilize waste materials, is well-suited for use as an insulating layer in building structures. This study experimentally examined the mechanical properties of CFC by varying design densities, fly ash incorporation ratios, and ceramsite densities to identify the primary factors influencing its mechanical performance. Additionally, the evolution of the internal pore structure of CFC was analyzed. The results indicate that design density significantly affects the mechanical properties of CFC, with compressive strength increasing as density increases. A relationship established between the strength of CFC and its cement content provides a basis for calculating the binder dosage in mix design. Increasing the density of CFC shifts its internal pore structure toward a coexistence of both small and large pores, thereby optimizing the overall pore composition. Furthermore, a strength-porosity model was developed to predict strength based on the relationship between mix proportion and porosity, enhancing design accuracy. These findings offer valuable theoretical support and practical design guidelines for the application and promotion of CFC in the construction materials sector. • Both the compressive strength and fluidity of CFC increase with its design density CFC with 30 % ceramsite content and a design density of 700 kg/m³ exhibits effective synergy between the ceramsite and matrix, achieving an optimal balance between mechanical performance and material cost. • As the design density increases, the proportion of small pores in CFC rises significantly, while the proportion of large pores decreases. Both the average pore size and overall porosity systematically decrease. Additionally, variations in fly ash content and ceramsite density influence the pore structure and porosity of CFC. • A quantitative relationship between the compressive strength of CFC and both cement content and porosity was established using multiple linear regression. A predictive model was developed to estimate strength based on mix proportions and porosity, significantly improving the accuracy of mix design.