Development and Validation of an Improved Elastic Modulus Prediction Model for High-Strength Fly Ash Ceramsite Lightweight Aggregate Concrete

The large-scale application of high-performance fly ash based ceramsite is an effective way to achieve high-value utilization of solid waste such as fly ash. This study investigates high-strength fly ash ceramsite lightweight aggregate concrete (with ceramsite cylinder compressive strength exceeding 20 MPa), focusing on the development of an elastic modulus prediction model and mix design methodology based on compressive strength and apparent density. By integrating a large amount of literature data, we compared and analyzed the elastic modulus prediction models based on compressive strength and apparent density proposed by different scholars. Based on this, we optimized and proposed a modified prediction model with wider applicability and higher accuracy. To simplify the mix design of lightweight aggregate concrete with ceramsite, a calculation model for compressive strength and apparent density of concrete based on physical parameters of mortar and solid waste based ceramsite was further established. The verification of the elastic modulus test of high-strength ceramsite lightweight aggregate concrete shows that the prediction model for the elastic modulus of lightweight aggregate concrete based on the calculation model of concrete compressive strength and apparent density is applicable to ceramsite lightweight aggregate concrete with compressive strength of 20–110 MPa, elastic modulus of 10–45 GPa, and apparent density of 1250–2350 kg/m3. The predicted value is about 7.0% lower than the experimental result, which can provide a safety margin for engineering mix design. The research results not only realize the high-value utilization of industrial solid waste such as fly ash, and also expand the application scope of solid waste based ceramsite in structural engineering, but also provide important theoretical basis and technical support for the development of lightweight, high-strength and green concrete.