Application Of Tunnel Waste Gneiss In Cement-stabilized Macadam Base Course Materials

With the rapid development of highway engineering,the number of tunnel construction is increasing,and the number of tunnel slags generated is also increasing rapidly.The utilization rate of tunnel slag is very low,resulting in waste of resources and environmental pollution,and increasing construction costs.Therefore,it is particularly important to study the application of tunnel slag in cement stabilized gravel base.Based on the Xi Fu expressway project,a lot of experiments and application studies have been carried out on the tunnel waste residue as the base.The main research contents and conclusions are as follows:Firstly,the characteristics of tunnel slag are studied.The mineralogical characteristics and physical and mechanical properties of tunnel slag show that the slag of tunnel slag is gneiss,the main mineral components are feldspar,biotite,quartz and hornblende.The uniaxial compressive strength,softening coefficient,needle-like content,Los Angeles wear and other engineering properties of gneiss gravel are in line with the Technical Specifications for Highway Bridges and Culverts(JTG/T F50-2011).Through the study of the effect of vibration stirring on the cement stable gravel,the conclusion that the effect of vibration stirring on the uniformity and strength of the mixture has been improved is obtained,and it is advisable to adopt the vibration stirring technology.Secondly,the pavement performance of cement-stabilized gravel base material was studied,with the cement content of 3.0 percent,3.5 percent,4.0 percent,4.5 percent and 5.0 percent,plus the fly ash of different doses.The test pieces were prepared by vibrating molding.The results show that the strength and stability of specimens increase with the increase of cement content,and the shrinkage performance decreases with the increase of cement content.The road performance of cement-stabilized gneiss gravel is slightly worse than that of cement-stabilized limestone gravel.When adding 4.5% cement,the properties of the materials meet the requirements of the technical rules for the basic construction of highway pavement(JTG/T f20-2015).The performance of adding fly ash to cement stabilized gravel has been improved.Finally,the key points of the construction plan are formulated according to the characteristics of the physical project.The tunnel waste gneiss was mixed with 4.5% cement to mix the mixture,and the pavement base was paved with 100 m test section.Quality inspection was conducted by field test method,which verified the feasibility of the tunnel slag gneiss applied to cement stabilized gravel base.