Asphalt mixture recycling technology is a complete set of technology that involves turning over, recycling, crushing and screening the asphalt pavement that needs to be renovated or abandoned, combining with new aggregates and soft asphalt materials appropriately, and remixing to form recycled asphalt mixture with road performance requirements for paving the pavement surface layer or base layer. It is basically suitable for all kinds of asphalt pavement construction, can save most of the aggregate and about 30% of the asphalt, and its use effect is comparable to or close to the soft asphalt mixture. The recycling of asphalt mixture reduces the use and cost of new materials and reduces the cost of road construction. According to the United States Federal Highway Administration survey, it can save more than 50% of the material cost, reduce the road cost by about 25%, and save 50% of the asphalt.
Heat regenerative mixing equipment
Asphalt Plant mix heat regeneration equipment can be divided into intermittent and continuous two structural forms:
Intermittent asphalt regeneration equipment: the generally recognized is the second drying cylinder heating and recycling technology. The equipment needs to be equipped with a special system on the basis of the original mixing equipment, which includes the crushing and screening system of the old asphalt mixture, the supply system, the lifting system, the drying system, the combustion system, the storage and weighing system and the treatment system of harmful gases. Asphalt mixing equipment produced by foreign manufacturers such as Benning Hofer, Marani, Rigong, Oman and other companies have this function. However, the same problem exists: the drying system should ensure that the old recycled material reaches a certain temperature, and ensure that the asphalt adsorbed on the surface does not age. The treatment of harmful gases requires the absorption of harmful gases released by heating and storing old mixtures without causing pollution to the environment. In order to ensure that the old and new materials are mixed evenly and the old and new asphalt are fully coated evenly, the mixing time needs to be increased, so the output of the equipment has decreased. In theory, the old asphalt mixture can be recycled up to 100%, but in actual production, it can only be added to less than 50%. Although the recovered material has been screened, its grading cannot meet the requirements of asphalt mixture. The temperature of the old recycled material can not meet the requirements of the asphalt mixture (usually the old recycled material heated to more than 130 ° C will produce a lot of smoke and harmful gases and can not be fully absorbed), it is necessary to add new aggregate to increase the temperature of the new aggregate, and use part of the heat of the new aggregate to heat the old recycled material.
Continuous asphalt regeneration equipment: the most widely used and most representative is the double drum regeneration mixing equipment produced by ASTEC (Astech) Company in the United States. After drying the sifted and graded aggregate, it enters the mixing cylinder on the outer wall of the drying cylinder at one end of the burner and mixes with the old recovery material that has just entered. The old recovery material is heated by the hot aggregate and the thermal radiation on the outer wall of the drying cylinder, so that the old asphalt mixture is completely separated from the flame and the asphalt will not age. The mixture is forced to mix by the mixer installed on the outer wall of the drying cylinder (similar to the single-horizontal shaft mixer), because the length of the drying cylinder is up to seven meters, the mixing time of the old and new materials in the double drum can reach 60 to 90 seconds, so that the mixture is evenly mixed. After the harmful gases produced in the process of mixing the old and new materials are returned to the combustion chamber, the asphalt gas and harmful gases entering the dust collector are greatly reduced. Reduce the secondary pollution to the atmosphere. The equipment from the aggregate metering, conveying, heating, mixing to the delivery of finished materials, are continuous, its structure is relatively simple, high output, low failure rate, can add 50% of the old recycled materials.
