Balanced design method for high-temperature creep and low-temperature relaxation performance of recycled asphalt mixture

Abstract

The invention discloses a high-temperature creep and low-temperature relaxation performance balance design method for a recycled asphalt mixture. The method comprises the following steps: drawing up the RAP mixing amount; determining an initial asphalt-aggregate ratio and a regenerant mixing amount; preparing n groups of different recycled asphalt mixtures; testing to obtain creep indexes and relaxation index values of the original sample asphalt mixture and the recycled asphalt mixture; standardizing creep index and relaxation index values of the recycled asphalt mixture so as to eliminate the influence of different index dimensions; calculating equilibrium points of high-temperature creep and low-temperature relaxation performance; comparing the high-temperature creep and low-temperature relaxation properties of the recycled asphalt mixture at the equilibrium point with the original asphalt mixture; and determining an optimal balance point of high-temperature creep and low-temperature relaxation performance. According to the method, the recycled asphalt mixture is subjected to balance design from the viscoelasticity, the mixing amounts of the recycling agent and the original asphalt under different RAP mixing amounts are determined, and a new thought is provided for design of the recycled asphalt mixture.

Description

technical field [0001] The invention belongs to the technical field of recycled asphalt mixture design, and particularly relates to a balanced design method for high temperature creep and low temperature relaxation properties of recycled asphalt mixture. Background technique [0002] As the highways of various grades that have been built in my country have successively entered the period of major repair or reconstruction, the recycling of waste asphalt mixture has become an inevitable trend. But the aged asphalt in RAP (Recycled Asphalt Material) exhibits higher stiffness and lower stress relaxation capacity due to excessive oxidation. Therefore, in order to improve the road performance of reclaimed asphalt mixture, it is generally necessary to add regenerant, new asphalt and new aggregate to RAP. As a result, the composition of the mixture is more complex, and its performance is quite different from that of the original asphalt mixture. Traditional evaluation indicators ba...

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Problems solved by technology

[0004] At present, most of the research on the high and low temperature performance balance design of recycled asphalt mixtures is based on rutting and crack resistance tests. The current high and low temperature performance balance design methods of recycled asphalt mixtures still have the following limitations: 1) The evaluation indicators based on strength theory or deformation theory are difficult to be accurate 2) only consider different RAP content, without comprehensively considering the impact of the content of RAP, regenerant and asphalt; 3) generally determine the upper and lower limits of high and low temperature performance indicators according to the specifications , and finally select the median or intersection point of the two as the balance value within the limited range, the reliability and accuracy of the balance design are poor

However, the above-mentioned patents have the following limitations: (1) There are obvious differences in the mechanical properties and rheological models of asphalt and asphalt mixture, and it is not practical to use only asphalt to determine the amount of regenerant; (2) Regeneration only through aging asphalt Determine the amount of regenerant, and RAP regeneration, the original asphalt has played a very important role (3) It is necessary to extract and recover the old asphalt from a large amount of milling material RAP to meet the representative requirements, the process is cumbersome and the workload is heavy

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