Analysis of applicability and influencing factors of elastic modulus prediction model of lightweight aggregate concrete

Elastic modulus is an important mechanical performance indicator of lightweight aggregate concrete (LWAC). In this paper, lightweight aggregate concrete is regarded as a two-phase body composed of mortar and lightweight aggregate. In the range of conventional performance parameters of lightweight aggregate concrete, the relationship between its elastic modulus and mortar and lightweight aggregate is investigated. Considering 7 MPa ordinary strength ceramsite lightweight aggregate, 23 MPa high-strength ceramsite lightweight aggregate and 60 MPa, 80 MPa high-strength mortar, experiments were designed with mortar elastic modulus, lightweight aggregate elastic modulus, and lightweight aggregate volume fraction as research variables. Combining 275 sets of experimental data from relevant research literatures, the applicability of the concrete elastic modulus prediction model based on the two-phase composite assumption in lightweight aggregate concrete is compared and verified by experiments. The prediction accuracy of each model is evaluated, and the prediction model suitable for the elastic modulus of lightweight aggregate concrete is identified. The results indicate that (1) the elastic modulus of mortar, the elastic modulus of aggregate, and the volume fraction of aggregate are key factors influencing the elastic modulus of lightweight concrete. (2) Testing has confirmed that a single series or parallel mode in the two-phase composite model cannot accurately predict the elastic modulus of lightweight aggregate concrete. The series model yields the lowest prediction, while the parallel model provides the highest prediction. Among the two-phase composite models, the Maxwell model and the Counto model exhibit superior prediction accuracy, with mean ratios of the predicted results to test results being 1.003 and 1.001, respectively, which are very close to 1. Furthermore, all predicted results deviate from the test results by less than 5 %, as verified by relevant research literature data. (3) Experimental data from high-strength ceramsite lightweight aggregate concrete with a cylinder compressive strength of 23 MPa further validate that the Maxwell model and Counto model are suitable for predicting the properties of high-strength lightweight aggregate concrete. The average ratio between predicted and test results are 1.000 and 0.999, approximately equal to 1. The research results of this paper determine the prediction model suitable for the elastic modulus of lightweight aggregate concrete and broaden the scope of application of the prediction model, in order to provide support for the design and prediction of the elastic modulus of lightweight aggregate concrete, and promote the application of high-strength lightweight aggregate concrete in high-rise buildings, long-span bridge and other fields.