Improving the mechanical properties of cold-bonded coarse aggregate concrete from municipal solid waste incineration bottom ash through compression casting technology

The preparation of cold-bonded coarse aggregates from municipal solid waste incineration bottom ash for concrete production can achieve the resource utilization of municipal solid waste incineration bottom ash and alleviate the shortage of natural aggregates. However, the poor performance of the concrete hinders its widespread application. To address this issue, a compression casting technique is proposed to improve the mechanical properties of the concrete. The effects of cold-bonded aggregate substitution rates (0-100%), casting methods (normal casting and compression casting), and compression parameters (pressure, time, and height) on the stress-strain behavior of concrete were examined. Results showed that increasing the cold-bonded aggregate substitution rate reduces the compressive strength and elastic modulus for both normal casting concrete and compression casting concrete. The maximum decreases in peak stress and elastic modulus of normal casting concrete were 28% and 45%, respectively. In comparison, the peak stress of compression casting concrete increased by more than 60%, and the elastic modulus improved by 90%, although its specific toughness decreased by 40%. Compression parameters had less effect on the mechanical properties of concrete. The optimal parameters are a pressure of 5 MPa, a time of 2 min, and a height of 300 mm. Furthermore, a novel stress-strain model is proposed that effectively predicts the stress-strain behavior of concrete across different cold-bonded aggregate substitution rates. Overall, this study offers a promising solution for enhancing the performance of cold-bonded aggregate concrete and lays the foundation for its practical application.