Study on Mechanical Properties of Recycled Mixture with High Content of Iron Tailings Sand

This paper focuses on the disposal of iron tailings sand (ITS) and reclaimed inorganic binder stabilized aggregate (RAI), and a new “ITS plus RAI” solid waste treatment method is innovatively proposed, which uses ITS and RAI as a new base course material to replace of new aggregates by 100%. It is found that the new ITS and RAI mixture has excellent compressive performance by designing the material composition of the mixture, which can meet the design strength of different levels of pavement under various load conditions. A series of laboratory tests are used to study the effect of the content of special cementitious material and iron tailings on the uniaxial compressive strength, flexural-tensile strength, compressive resilience modulus, and flexural-tensile resilience modulus of recycled mixture. And, the scanning electron microscope test (SEM) and X-ray diffraction test (XRD) are used to compare the surface morphology characteristics and hydration products of the recycled mixture under different ratios and to discuss the formation mechanism of the strength of the mixture. The test results show that the macroscopic change pattern in laboratory tests is basically consistent with the results in microanalysis. The relationship between compressive strength and compressive resilience modulus and flexural resilience modulus is also established by linear regression. This solid waste treatment method is applied to the pavement renovation project of national and provincial roads in Shanxi Province (within Linfen), to replace the existing base material by using recycled mixture, and the results show that it can save not only the carbon emission from stone mining and processing but also the construction cost, while producing good social and economic benefits and promoting the process of carbon neutralization in the world.