关键词: 道路工程, 评价指标, 发泡效果, 非接触式方法, 膨胀率, 半衰期, 泡沫沥青

Abstract: In view of the fact that the existing evaluation indexes of foamed asphalt, that is expansion rate and half-life,had shortcoming in evaluating the foaming effect of foamed warm mix asphalt, three evaluation indexes such as foam diameter, size distribution and defoaming rate were proposed to evaluate the foaming effect of foamed warm mix asphalt, which was according to the result of non-contact test method based on laser range finder, digital camera and other equipment. The test results show that the water consumption has greater influence on foam diameter than the asphalt temperature, which verifies the water consumption has greater influence on asphalt foaming effect than asphalt temperature.The 90 s foam size distribution is the most concentrated, which is consistent with the foam stability mechanism in asphalt foaming.The k value of defoaming rate increases with the increase of water consumption,which confirms that the half-life decreases with the increase of water consumption. In addition,the change of defoaming rate shows that the foamed asphalt can improve the workability of asphalt mixture during mixing, transportation, paving and rolling stages.So non-contact test method combining with the proposed three indexes can accurately characterize the whole process of asphalt foaming and better evaluate the foaming effect, which is helpful to find the best mixing time points, foaming temperature, water consumption and etc. according to actual construction requirements of foamed warm mix asphalt.

Key words: highway engineering, evaluation index, foaming effect, non-contact method, expansion rate, half-life, foamed asphalt