Abstract: Detecting and quantifying surface bugholes on concrete is a crucial aspect of evaluating the appearance quality of concrete. Relying solely on the size of bughole is insufficient to comprehensively assess the appearance quality of concrete. In this study we consider the influence of bughole quantity on the evaluation of concrete’s appearance quality. Based on fuzzy mathematical methods, we employed a grey relational analysis approach to establish an evaluation model with the maximum diameter, area ratio, and number of bugholes as the factor set. This model comprehensively evaluates the appearance quality of concrete and explores the impact of different proportions of defoamers and air-entraining agents on the appearance quality of concrete based on the evaluation results. Results demonstrate that 1) the coefficient of correlation between the CIB grade and the number of bugholes is 0.929 74. Through regression analysis, we propose a grading index for the number of bugholes. Factors in the factor set have different degrees of influence on the appearance quality of the formed concrete, with the maximum diameter of bugholes having the greatest impact, followed by the number of bugholes, and finally, the area ratio. Therefore, the number of bugholes should be considered as an important factor affecting the appearance quality of formed concrete. 2) When the dosage of defoamer is less than 0.3‰, the size and number of bugholes decrease with an increase in the defoamer dosage and increase with an increase in the air-entraining agent dosage. When the dosage of defoamer exceeds 0.5‰, the corresponding values increase with an increase in the defoamer dosage while decrease with an increase in the air-entraining agent dosage. An appropriate proportion of additives can effectively improve the appearance quality of the formed concrete. 3) The grading method based on fuzzy mathematics can accomplish the evaluation of concrete’s appearance quality. According to the comprehensive evaluation results, the best appearance quality of concrete is achieved when the dosages of defoamer and air-entraining agent are 0.5‰ and 0.15‰, respectively.

Key words: concrete, appearance quality, regression analysis, fuzzy mathematics, defoamer, air-entraining agent, fuzzy comprehensive evaluation