Influence of foaming water content on foam asphalt mixtures

•We studied the influence of water content and addition of cold aggregate fraction in foamed asphalt mixture.•We examine main parameters influencing foam asphalt mixture, mixing and compaction temperature.•Gyratory and marshal compaction methods were implemented for compaction.•Marshall stability test and ITS were used to analyze the influence of compaction and mixing temperature.•Thermogravimetric analysis (TGA) analysis is made to determine the residual water content in the foam asphalt mixture. Warm mix asphalt technology using foamed bitumen is being used widely despite the fact that high air void content and poor coating of large aggregate remain major drawbacks require enhancement. This paper manly focuses on the investigation of water content influence on the foamed bitumen and the asphalt mixture. Influence of the water content in combination with compaction temperature has been investigated using gyratory compaction method. AC11N foam asphalt mixture is produced in the lab using lab foamer. Marshall stability and indirect tensile test was used to evaluate the foam asphalt mixture performance. The investigation revealed that the Marshall stability of foam asphalt mixture is highly influenced by compaction temperature compared to water content. Moreover, increasing the water content helps in coating large aggregates when the mixture is produced at low temperature, nevertheless using high water content reduces the Marshall stability to certain extent. In addition the amount of water trapped in the mixture after the mixing process was determined using thermogravimetric analysis. The amount of water remaining in the asphalt mixture is less than 1% relative to the bitumen mass.