In recent years, the recycling of asphalt recycled materials (RAP) and its reuse as an alternative material in the manufacture of rolled concrete (RCC) for use in paving has been growing. Recycled asphalt additives have been compacted into concrete samples in previous research. And the use of 50% RAP coarse-grained components is recommended in concrete pavements. The most important obstacle observed in these studies, after the combination of RAP in concrete pavement, is the weak bond between the asphalt layer and the cement matrix, which results in the creation of a weak surface zone (ITZ). Which subsequently About 50% of the properties associated with concrete strength are reduced. In the present study, in order to improve the quality of asphalt materials and eliminate this weakness, 5 methods of abrasion, acid washing, stabilization, emulsifier and use of pozzolanic materials were performed for pre-treatment of recycled asphalt particles and with modified materials, roller concrete containing 100 % Coarse-grained asphalt materials were made. Compressive strength test was also used to compare different methods. The stabilization method was selected by preheating the materials and spraying cement at a rate of 7% by weight on the recycled asphalt. In the second part of the research, the stabilization method is used to modify asphalt materials and to investigate the mechanical properties and durability of roller concrete containing asphalt aggregates, natural aggregates with 50, 75 and 100% by weight are replaced with modified and unmodified asphalt materials. And were compared with control concrete containing 100% natural materials. Compression, tensile and flexural strength tests were used to eva‎luate the mechanical properties, and water absorption, permeability and abrasion resistance tests were used to eva‎luate the durability properties. According to experiments, with increasing the percentage of replacement of aggregates, the mechanical properties of concrete are reduced. By replacing 100% of the asphalt aggregate, the compressive strength of roller concrete has been reduced by about 50%. Modification of asphalt materials by stabilization method has improved the quality of recycled asphalt particles. With the stabilization of asphalt materials, the compressive, tensile and flexural strength in roller concrete samples containing 100% of modified asphalt aggregates has been increased by 27, 22 and 37% compared to the samples containing unmodified materials, and the minimum amount of resistance stated in the Iranian and American regulations has been reached. Regarding the durability characteristics of adding recycled asphalt chips in different percentages to roller compacted concrete, it has reduced water absorption, increased permeability and increased wear. With the modification of materials, the rate of water absorption and permeability in samples containing modified materials compared to samples containing unmodified materials has decreased. Fixation of materials has improved the abrasion resistance of roller concrete containing modified materials compared to samples containing unmodified materials. The wear rate of the sample containing 75% of the modified recycled asphalt is very close to the wear resistance of the control sample containing 100% of natural materials.

مهدي ابطحي، داود مستوفي نژاد

عليرضا سلجوقيان، ابوالفضل اسلامي