Research On Recycling Technology Of Waste Semi-rigid Base Materials

With the rapid development of highway construction,China’s highway construction is gradually changing from a high-speed construction period to a parallel period of construction and maintenance.A large amount of waste pavement materials in the repair project waste China’s natural resources and generate dust and pollute the environment.At the same time,China is still a big country producing soda.A large amount of soda residue pollutes the environment,occupies land resources,and endangers health.If alkali slag is added during the regeneration of the waste semi-rigid base materials,not only the waste base materials can be consumed,but also the unlimited expansion of the alkali slag mountain can be restrained,protecting the surrounding environment of the alkali plant,and alleviating the insufficient supply of road building materials.Improve the comprehensive utilization of alkali residue and recycled road materials.The thesis focuses on the subject of recycling and reuse of waste base materials,systematically analyzes the performance of different base materials to prepare recycled base materials,and focuses on the effect of alkali residue as an alkali-active admixture on the waste base materials.First,the optimal water content and maximum dry density of four cement regeneration schemes and nine secondary ash regeneration schemes were obtained through compaction tests.Based on this,an unconfined compressive strength test was performed to obtain the cement regeneration scheme and secondary ash regeneration scheme Based on this,the alkali slag was mixed with the lime ash-alkali slag regeneration technology scheme,and the cement-alkali slag regeneration technology scheme was put forward,and the optimal mixture ratio was obtained.The main mechanical properties of the four types of recycled materials,such as unconfined compressive strength,splitting strength,compressive rebound modulus,and dynamic modulus,were studied,and the change law of mechanical strength with the amount of regeneration agent and the increase of curing age was obtained.And established unconfined compressive strength and splitting strength,unconfined compressive strength and compressive rebound modulus,unconfined compressive strength and dynamic modulus,compressive rebound modulus and dynamic modulus as a function of the relationship,experiments show that the early strength of the recycled material mixed with alkali slag is higher.The road performance of recycled materials has been studied.The dry shrinkage coefficients of the four recycled materials have been increasing with time,and the growth rate has slowed down;the temperature shrinkage coefficients of the four recycled materials have increased and then decreased with the increase of temperature.The trend is small,and the peak value is between0 ℃～10 ℃;the anti-shrinkage performance of the lime-fly ash-alkali residue regeneration scheme is the best.The water stability coefficient and freezing stability coefficient of the four recycled materials are all above 0.8,which has better water stability and freezing stability,and the cement-alkali residue regeneration scheme has the best stability.Micro-tests of recycled materials were carried out.With the increase of age,the content of generated minerals increased,and a large number of rod-shaped and fibrous ettringite and mullite crystals were formed.The cement and the cement are bonded together;the recycled material mixed with the alkali slag has a fast reaction speed,and a small amount of crystalline material will be generated at the beginning of the test,which will adhere to the surface of the aggregate and improve the early strength of the recycled material as a whole.The mechanical properties and road performance of the waste semi-rigid base course materials recycled by alkali slag can meet the corresponding practical requirements,save costs,and meet the current sustainable development requirements.It is a good technology for the transformation and regeneration of waste semi-rigid base courses.It has important social,economic and environmental benefits.