With increasing global emphasis on sustainable infrastructure development,asphalt pavement recycling technology has become a focal point in the industry.The standardization and scientific rigor of recycled asphalt(RAP)sample preparation directly determine the accuracy of recycled asphalt mixture performance evaluation and the success of engineering applications.This article will clearly explain this key process and the international standards upon which it is based.

I.Standardized Preparation:The Cornerstone of Data Reliability

The preparation of recycled asphalt samples is not a simple material processing procedure,but rather a series of interconnected standardized operating procedures.

1.Fine Pretreatment

Large pieces of RAP material need to undergo preliminary crushing and sieving in the laboratory to obtain representative samples,while strictly controlling over-crushing to maintain their original gradation characteristics.

2.Core Recycling Steps

Using specialized methods such as solvent extraction or combustion,recycled asphalt is effectively separated from the aggregate.This process requires extremely precise control of temperature and time to obtain pure asphalt while preventing secondary aging.

3.Key Homogenization Steps

The separated asphalt needs to be thoroughly stirred under controlled temperature to achieve homogeneous properties.This crucial operation strictly adheres to the international standard ASTM D5404/D5404M,"Standard Practice for the Separation of Recycled Bituminous Asphalt from Solution,"providing a repeatable and comparable data foundation for all subsequent tests.

4.Standardized Sample Formation

According to different test requirements such as penetration and rheological properties,asphalt is injected into a standard mold.After cooling and temperature conditioning,a standard sample meeting the test conditions is formed.Attention to detail is emphasized throughout the process to avoid introducing air bubbles or uneven thickness.

II.International Standards:The Technical Language Connecting Global Practices

In the globalized fields of engineering and scientific research,international standards serve as a universal language to ensure technical consistency and facilitate the exchange of results.In the field of recycled bitumen sample preparation,international standards provide comprehensive guidance,covering equipment,methods,and safety.

In addition to the aforementioned ASTM standards,the European standard EN 12697-3,"Asphalt mixtures—Test methods—Part 3:Asphalt recycling—Rotary evaporator method,"is also widely adopted globally.This standard provides detailed specifications for each step,parameter,and safety requirements of recycling using a rotary evaporator,significantly improving the reliability and comparability of data from different laboratories.

Following these international standards means that my country's scientific research and practical achievements can seamlessly connect with international frontiers,participate in global technical dialogues,and also provide a solid technical basis for the development and optimization of localized standards.

III.Towards a Sustainable Future

Standardized sample preparation is an indispensable link in the asphalt recycling technology chain.It is not merely a laboratory procedure,but a crucial technological support for promoting a circular economy,reducing resource consumption,and lowering carbon emissions.By strictly adhering to international standards such as ASTM and EN,we can ensure that the performance of asphalt materials"reborn"from waste pavement is realistically and scientifically evaluated,thus enabling their safe and efficient return to roads and paving a solid path for sustainable development.

Mastering standards is essential to giving old materials new life.With continuous technological advancements and deepening international cooperation,standardized and refined asphalt recycling processes will undoubtedly contribute even greater value to the construction of green transportation infrastructure.