| Although the traditional concrete road maintenance materials are easy to use,there are disadvantages such as low early strength,slow setting and hardening,and poor crack resistance,which limit its application in concrete road maintenance and repair projects.While the fast hard cement-based maintenance materials,although high early strength,fast hardening speed,but at the same time there are high production costs,late strength inversion shrinkage,early hydration exothermic concentration,prone to swelling cracking and other problems,through the incorporation of mineral admixtures,fibers,etc.can effectively solve the above problems.Therefore,in order to further enhance the maintenance efficiency,reduce the cost of material use and improve the mechanical properties of materials,this paper carried out a fast hardening micro-expansion high anti-cracking maintenance material preparation and performance research,the specific content and results are as follows:（1）Preparation of ultrafine mineral admixtures from industrial solid wastes.By setting the grinding time gradient,studying the influence law of the ease of grinding,activity and mobility of different solid waste raw materials steel slag,slag and fly ash,determining the best grinding time and compounding it,further optimizing the ratio design of industrial solid waste ultrafine mineral admixture,obtaining the formulation of industrial solid waste ultrafine mineral admixture:grinding time is 90min,steel slag powder:slag powder:fly ash powder is3:5:2,the 28d activity index is 103%,and the performance reaches S95 grade.（2）Study on the preparation and performance of fast hardening colloidal sand.The recommended dose of lithium carbonate in fast-hard cement is 0.04%of the cement mass.The type of hydration products and fine microscopic morphology of cement paste at different ages were analyzed by XRD and SEM tests.The results show that:ultrafine mineral admixture and lithium carbonate have no effect on the type of hydration products,and ultrafine mineral admixture weakens the crystalline phase transformation effect of cement paste late strength inversion;considering different lithium carbonate admixture and introducing different colloidal sand mixing process,fast 12h flexural and compressive strengths of 6.5MPa and 43.5MPa fast hard colloidal sand were prepared;studying the effect of ultrafine mineral admixture on the young age frost resistance,erosion resistance and permeability resistance of fast hard colloidal sand.The results show that the amount of superfine mineral admixture of 5%～10%can improve the flexural and compressive strength by about 4 percentage points.（3）Preparation and application of fast-hard micro-expansion high anti-cracking maintenance materials.Through the orthogonal test method,the fast hard micro expansion high anti-cracking maintenance material was prepared,and the influence law of water-cement ratio,superfine mineral admixture,cement-sand ratio and steel fiber on the mechanical properties and working performance of fast hard micro expansion high anti-cracking maintenance material was systematically studied,and through comprehensive analysis,the best ratio of established raw materials was derived,and the plastic expansion agent was mixed in to further obtain the optimal ratio:A2B1C2D3+0.02%plastic swelling agent,6h flexural and compressive strength of 6.7MPa and 26.9MPa respectively,6h repair structure bond strength of 3.65MPa,56d limit expansion rate of 326.5×10-6,through the engineering demonstration application,to achieve the fast hard micro expansion high anti-cracking maintenance material maintenance and repair of open traffic within 6h. |
