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

摘要： 针对现有泡沫沥青评价指标——膨胀率和半衰期用于评价泡沫温拌沥青发泡效果存在不足，在基于激光测距仪、数码相机等设备的非接触式试验方法上提出采用泡沫直径、尺寸分布、消泡速率评价泡沫温拌沥青发泡效果。试验结果表明：泡沫直径受用水量影响比沥青温度大，印证了用水量比沥青温度对沥青发泡效果影响更大；90 s泡沫尺寸分布最集中，符合沥青发泡中泡沫稳定机理；消泡速率k值随用水量增大增加，印证了随用水量增加半衰期减小的结论；此外，从消泡速率变化情况表明泡沫沥青在拌合、运输、摊铺碾压阶段均可提高沥青混合料和易性。非接触试验方法与3个指标相结合能较准确的表征沥青发泡的整个过程，更好的评价发泡效果，有助于按照实际泡沫温拌沥青施工要求找到最佳的拌合时间点、发泡温度、用水来量等条件。

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