Optimization Evaluation of Quality Classification of Concrete with Recycled Coarse Aggregate

In order to overcome the errors caused by the subjective and discretionary factors of the recycled aggregate, select their quality scientifically and reasonably, a quality evaluation model for concrete with recycled coarse aggregate was established based on the combined weight-extension theory. According to the standard of concrete with recycled aggregate, the evaluation index system and limits of classification level were determined, the subjective and objective weights of each indexes were determined by the analytic hierarchy process (AHP) and entropy weight theory. The sample correlation degrees of each indexes under different levels were solved based on the extension theory, and then the correlation function values of the sample under different levels were calculated combined with the combination weight method. The quality grades were evaluated according to the principle that the bigger the number, the better the quality, finally, the scientificity of the evaluation method was tested by examples. The results show that: comprehensive evaluation method based on combined weight-extension theory not only follow the evaluation steps of the single factor method, but also can sort and compare the results under different levels of indicators; the quality grades of the five samples groups are calculated as II, I, I, II, and I, respectively, which are consistent with the evaluation results used by previous fuzzy theory; three weighting methods can not only calculate the specific weight values of seven performance indexes of the recycled coarse aggregate, but also can reflect the relative importance of each indexes. The study on the quality optimization of recycled coarse aggregate can provide a theoretical reference for the engineering application of recycled concrete.